graptolites in british stratigraphy

Geol Mag 146 (6 ) 2009 pp 785ndash850 ccopy Cambridge University Press 2009 785doi101017S0016756809990434

Graptolites in British stratigraphy

J A ZALASIEWICZdagger L TAYLOR A W A RUSHTONDagger D K LOYDELLsectR B RICKARDSpara amp M WILLIAMS

lowastDepartment of Geology University of Leicester University Road Leicester LE1 7RH UKDaggerDepartment of Paleontology Natural History Museum Cromwell Road London SW7 5BD UK

sectSchool of Earth and Environmental Sciences University of Portsmouth Burnaby Building Burnaby RoadPortsmouth PO1 3QL UK

paraDepartment of Earth Sciences University of Cambridge Sedgwick Museum Downing StreetCambridge CB2 3EQ UK

(Received 2 January 2008 accepted 25 September 2008 First published online 9 September 2009)

Abstract ndash 697 taxa of planktonic graptolites are recorded and their stratigraphical ranges are giventhrough 60 biozones and subzones in the Ordovician and Silurian strata of England Wales andScotland in the first such stratigraphical compilation for Great Britain since the synthesis of Elles ampWood (1901ndash1918)

Keywords graptolites graptolite zones biozones biostratigraphy Britain

1 Introduction

Graptolites are extinct colonial hemichordates gener-ally considered to be closely related to the present-daypterobranchs They range in age from the middle ofthe Cambrian to the Carboniferous The graptolitesinclude the exclusively planktonic graptoloids thelargely benthic dendroids and also the benthic crust-oids tuboids cameroids and dithecoids (Rickards ampDurman 2006) The graptoloids are the focus of thisaccount They provide the primary means of correlationof Ordovician and Silurian strata in the UK andare fundamental to resolving the stratigraphical andstructural architecture of these rocks (eg Zalasiewicz2001) which were laid down in sedimentary basins onthe margins of the Palaeozoic Iapetus Ocean Majoroutcrops are in the Southern Uplands of Scotlandthe Lake District and the Howgill Fells of northernEngland and Wales and the Welsh Borderland OutsideGreat Britain graptolites are important also in earlyDevonian successions

The British graptolite biozonal and subzonalschemes are shown in Figures 1 and 2 In theearly Ordovician planktonic dendroids and then thedichograptid graptoloids were the most importantgroups These were succeeded by the diplograptidswhich were dominant throughout the rest of theOrdovician Dicranograptids and nemagraptids werealso important elements at various times in the mid- tolate Ordovician (Such terms are used here in a generalsense higher-level graptolite taxonomy is discussedin more detail in Mitchell 1987 and Mitchell et al2007)

Following near-extinction during the latest Or-dovician glaciation a few species of diplograptidssurvived into the earliest Silurian These gave rise

daggerAuthor for correspondence jaz1leicesteracuk

to the monograptids which diversified to dominatethe Silurian and Devonian seas worldwide (althoughin Great Britain graptolites disappeared from theshallowing marine basins late in the Ludlow) Normaldiplograptids persisted for a short while into theSilurian while retiolitid (lsquomeshworkrsquo) graptolites werelocally common and survived into the Ludlow Themorphologically diverse and rapidly evolving mono-graptids provide a fine resolution for the Silurianwith graptolite zones lasting on average well undera million years (Rickards 1976 1989 Zalasiewicz1990 Hughes 1995 Melchin Cooper amp Sadler 2004)by contrast the duration of graptolite zones in theBritish Ordovician averages c 2 Ma (Rushton 1990cf Cooper amp Sadler 2004)

2 Palaeoecology provincialism and distribution

Graptolites are commonly held to be lsquoidealrsquo zonefossils because they were widely distributed in marinewaters and so not bound by facies The situationthough is not as simple as this The graptoloids wereprobably holoplanktonic although there is still muchdebate about whether they floated more or less passively(eg Bulman 1964 see also discussion in Rigby ampRickards 1990 and Palmer amp Rickards 1991) oractively propelled themselves through the water (egKirk 1978 Bates amp Kirk 1984 1985 Rickards et al1998 Melchin amp DeMont 1995)

Planktonic graptolites have long been interpretedas largely lsquoopen oceanrsquo dwellers common in off-shore pelagic and hemipelagic sequences (lsquograptolitefaciesrsquo) and rare or absent in shallow water deposits(lsquoshelly faciesrsquo) Subsequent elaborations of this gen-eral observation included suggestions that graptoliteswere subject to depth control with near-surface anddeep-living taxa (eg Berry amp Boucot 1972 Bates amp

httpsdoiorg101017S0016756809990434Downloaded from httpswwwcambridgeorgcore Open University Library on 18 Jan 2017 at 091553 subject to the Cambridge Core terms of use available at httpswwwcambridgeorgcoreterms

786 J A ZALASIEWICZ AND OTHERS

Figure 1 British Ordovician graptolite biozones and subzones Zonal scheme based on that proposed by Fortey et al (1995) andadopted in the Ordovician Correlation Report of Fortey et al (2000) with subsequent modification to the Arenig to early Llanvirn byCooper et al (2004) refinement of the Caradoc by Bettley Fortey amp Siveter (2001) while the CaradocAshgill section of Englandand Wales shows the modified correlations suggested by Rickards (2002) Chronostratigraphy and radiometric dates after Ogg Ogg ampGradstein (2008)


Graptolites in British stratigraphy 787

Figure 2 British Silurian graptolite biozones and subzones Zonal scheme follows Rickards (1976 depicted) with modifications fromLoydell (1992ndash1993a) Zalasiewicz (1994) Loydell amp Cave (1993 1996) Zalasiewicz amp Williams (1999) and those proposed hereinChronostratigraphy and radiometric dates after Ogg Ogg amp Gradstein (2008)

Kirk 1984 Erdtmann 1976) or that they werecontrolled by lsquowater mass specificityrsquo with particularassemblages of taxa adapted to particular conditionsof temperature and chemistry (Finney 1986) while

competition from other (soft-bodied) macrozoo-plankton may also have restricted their occurrence(Zalasiewicz 2001) Finney amp Berry (1997) disputedthe notion of graptolites as truly ocean-going noting



their absence from many deep-water anoxic depositsand suggested that they were largely confined to theregion of the outer shelf and continental slope

Provincialism in the graptolites was particularlymarked in the Ordovician with well-defined lsquoAtlanticrsquoand lsquoPacificrsquo provinces between which it is oftendifficult to correlate This may have been due inpart to pronounced climatic gradients (Skevington1974) the Atlantic province representing temperateand the Pacific representing equatorial waters Morelocal provincialism is also common however withapparently coeval faunas of markedly different com-position being reported from different regions of theUSA interior (Finney 1986) and from the westernand eastern parts of the Welsh Basin (eg compare thefaunal successions in Hughes 1989 and Zalasiewicz1992a) Provincialism is less pronounced in the Silurian(Melchin 1989) and the British biozonal system can beapplied for much of the Silurian throughout much of theworld with relatively minor modifications (see Korenrsquoet al 1996 and Melchin Cooper amp Sadler 2004)

3 Taxonomy

One of the fundamental constraints on graptolitebiostratigraphy is the ability to discriminate consist-ently between taxa Many graptolites have a complexmorphology with many identifiable features that canbe measured and tabulated Nevertheless the identific-ation of graptolites is not by any means universallystraightforward partly because of the difficulty ofassessing levels of intraspecific variation and partlybecause of preservational factors (see below)

Furthermore in some early Ordovician dichograpt-ids while new thecae were being added to the growingtips of the colony the early-formed thecae continued togrow this gave rise to mature rhabdosomes that havea markedly different appearance from juvenile ones(Williams amp Stevens 1988 p 49) Later Ordoviciandiplograptid taxa are often difficult to classify becausethe phylogenetically significant patterns of the veryearliest growth stages (eg Mitchell 1987) can berecognized only in very well-preserved material

The Silurian monograptids are arguably more tract-able The development of a single stipe led to a greatdiversity in rhabdosome shape with different types ofstraight curved or plane- to helically spiralled forms(Figs 11ndash19) This was accompanied by the evolutionof a wide range of thecal types many of which canbe recognized even in indifferently preserved materialThe Silurian monograptids were thus very lsquoexpressiversquomorphologically Evolution is easy to see in themalthough it is uncertain whether it was actually morerapid than in the less easily interpreted Ordovician taxa

Taxonomic uncertainties continue to be the mostsevere constraint upon the use of graptolites inbiostratigraphy Many species are poorly understoodor inadequately described and those particularly in theolder literature can lsquomutatersquo in subsequent descriptionsto become in the words of N F Hughes imprecise

lsquoballoonrsquo taxa There are many instances of the type ma-terial of a lsquoclassicalrsquo species being too poorly preservedor inadequately described to serve as a referencespecimen by modern standards It has been commonalso for several distinct taxa to be described at varioustimes as the same species Conversely Loydell (1993bpp 330ndash1) has shown how Stomatograptus longusObut 1949 has over time acquired five additionalspecies names (junior synonyms) There remainsmuch taxonomic lsquohousekeepingrsquo to do much of itstraightforward but time-consuming Better definitionof taxa for instance by the wholesale refiguring oftype material (Zalasiewicz et al 2000 Zalasiewicz ampRushton 2008) should lead to greater refinement ingraptolite biostratigraphy

4 Preservation

The widespread occurrence of graptolites in Britishearly Palaeozoic successions is due to a phenomenonwhich is absent from recent oceans that of prolongedwidespread periods of sea-floor anoxia (Page et al2007 and references therein) Thus graptolites are typ-ically found in finely laminated hemipelagic deposits(lsquograptolite shalesrsquo) laid down in anoxic conditionsthat excluded benthos In Britain graptolites aregenerally rare or absent in rocks that were laid downunder oxygenated sea-floor conditions and that werecolonized and bioturbated by a benthic fauna (egDavies et al 1997)

British Ordovician and Silurian deep-water se-quences characteristically show an alternation of oxicfacies (lsquobarren bedsrsquo) and anoxic facies (lsquograptoliteshalesrsquo) (Rickards 1964 Cave 1979 Davies et al1997) These are most clearly seen in condensedpelagic deposits such as the Moffat Shale Group ofScotland and the Skelgill Beds of the Lake Districtwhere individual graptolite biozones tend to be onlya few metres thick In coarser clastic successionssuch as the kilometres-thick Silurian turbidite depositsof the Welsh Basin the lsquograptolite shalesrsquo take theform of millimetre- to centimetre-thick units betweenindividual turbidites

The relative proportion of lsquograptolite shalesrsquo andlsquobarren bedsrsquo exerts a strong control on the preservationof graptolites and hence on the resolution of graptolitebiostratigraphy In the Caradoc of Scotland andWales for instance the clingani Biozone is locallypreserved within continuously anoxic facies and thishas enabled detailed range charts (eg Williams 1982aZalasiewicz Rushton amp Owen 1995) to be constructedallowing the incomings and extinctions of speciesto be established thus offering the prospect of verydetailed correlation The complanatus Biozone of thelower Ashgill by contrast is preserved in the SouthernUplands of Scotland only as two 5 cm thick bedswithin a sequence of lsquobarren bedsrsquo several metresthick In Wales the complanatus Biozone has not beenrecognized probably due to an absence of anoxic faciesof that age



In highly expanded successions such as the SkiddawGroup of the Lake District graptolites can be raresimply through dilution by clastic sediment Most of theSkiddaw graptolites have been found not at exposurebut by searching through extensive screes (Cooperet al 1995 2004) The Manx Slates of the Isle ofMan are the equivalents of the Skiddaw Group butas there are few screes on the Isle of Man graptoliteshave only ever been found on two occasions a centuryapart (Bolton 1899 Rushton 1993) Further onelsquoManx Slatersquo lithofacies was recently shown to containlate Wenlock graptolites (Howe 1999) necessitatinga radical revision of geological interpretations of thatisland

Graptolites are preserved either diageneticallyflattened or in partial to full relief Flattened specimenscommon in condensed black shale successions mayoriginally have been encased in gelatinous lsquomarinesnowrsquo or microbial mats on the sea floor (JonesZalasiewicz amp Rickards 2002) The pyritized reliefmaterial which is common for instance in theLlandovery turbiditic sequences of Wales generallyshows more morphological information than canbe gleaned from flattened material However reliefmaterial may occasionally be more difficult to identifythan the lsquosimplersquo flattened silhouettes on whichmany specific descriptions were originally based forexample the characteristic apertural spines of thezone fossil Stimulograptus sedgwickii are normally notvisible on relief specimens being either broken off orembedded in the rock matrix Graptolites that can bedissolved from limestones or cherts to provide exquis-itely preserved isolated specimens are rare in Britishsequences (a notable exception is the Balclatchie faunafrom Scotland Bulman 1944ndash1947) however littleuse has been made of the graptolite fragments that areencountered while preparing samples for conodonts orchitinozoans

5 Graptolite biozones

The distinctiveness and usefulness of graptoliteassemblages were recognized midway through thenineteenth century notably by Joachim Barrande(1850) in Bohemia James Hall (1865) in CanadaGustav Linnarsson (1871) in Sweden and CharlesLapworth (1878) in the Southern Uplands of ScotlandBarrande and Lapworth both worked in areas thatare now realized to be characterized by many struc-tural dislocations and repetitions Barrande believedthat in any area these repeated assemblages wereenvironmentally controlled successively lsquocolonizingrsquo itwhenever conditions were right Lapworth interpretedhis assemblages to be temporally restricted and usedthem to demonstrate the multiple structural repetitionsof the Southern Uplands thus simultaneously solvinga major controversy of British regional geology andproviding one of the most precise correlative tools ingeology

Lapworthrsquos graptolite biozones as modified by Ellesamp Wood (1901ndash1918) are essentially those in usetoday though further refined and subdivided (egRickards 1976 Loydell 1992ndash1993a Loydell amp Cave1996) They are broadly assemblage biozones namedafter a species ideally with a restricted vertical rangeand a wide horizontal distribution (see Rickards1995) A name-giving species may be restricted toits biozone with its incoming being used to definethe zonal base (eg Monograptus riccartonensislsquoMonograptusrsquo crispus) It may equally range outsidelsquoitsrsquo biozone either above its upper boundary (egSpirograptus turriculatus Monograptus firmus) orexceptionally below it (eg Bohemograptus) Whatare important in the recognition of a biozone are thetotal assemblage and the incoming species Strictlyspeaking they are thus the Oppel biozones of theNorth American Stratigraphic Code but in practiceassemblage biozones are essentially the same Wherethe base of a biozone is defined by the incoming ofmore than one species it is realized that these speciesmay not appear exactly synchronously but in practicalbiostratigraphical collecting they commonly seem todo so particularly in condensed sequences

Graptolite biozones like biozones generally andunlike chronostratigraphical units are not fixed withinsections by lsquogolden spikesrsquo They may though havetype sections where they were originally describedenabling clear original definitions and forming thestarting point for subsequent redefinition either thereor elsewhere in the world

An alternative to the use of assemblage biozonesis the use of evolutionary lineages These are notso widely applied in the case of graptolites largelybecause the use of assemblage biozones is so suc-cessful Their use is also constrained by the relativelysmall amount of detailed work that has been doneon graptolite evolutionary lineages particularly withregard to determining whether these lineages showgradualistic or punctuational change In gradualisticlineages arbitrary lsquosnipsrsquo of a continuum must beselected while punctuational lineages are lsquonaturallyrsquobroken up into discrete taxon ranges It might besaid that the latter show evolution to be workingin a lsquodigitalrsquo fashion compared to the lsquoanaloguersquomechanism of the former Both punctuational andgradualistic modes of evolution may be inferred in thegraptolite record Punctuation may be invoked wheredistinctive species such as Aulograptus cucullus seemto lsquoappearrsquo globally without any trace of a directancestor though this observation must be viewed inthe knowledge that the evolution of such species mayhave taken place lsquoelsewherersquo (and perhaps slowly)that is in some marine basin that has not yet beenlocated Gradualistic modes of evolution have alsobeen recorded (eg Urbanek 1966 Sudbury 1958) itshould be remembered however that even lsquoestablishedrsquolineages are only hypotheses

There have been several modifications of grap-tolite biozones Numerical notation giving biozones



numbers rather than names has been used by someauthors This practice is a corruption of Elles amp Wood(1901ndash1918) who numbered their biozones as well asnaming them Elles and Wood though were simplyproviding a count The numbering of biozones is not aswell standardized as are names and the use of differentnumerical schemes for different regions is a recipe forchaos Numerical notation is best avoided

Interregna are low-diversity levels that may havevalue in practical correlation even defined on theoccurrence of long-ranging species (and thus on theabsence of other species) A familiar example isthe Wenlock Gothograptus nassaPristiograptus du-bius Interregnum established by Jaeger (1959) Pdubius is one of the longest-ranging graptolite speciesknown (early Wenlock to late Ludlow) while Gnassa has been recorded from significantly below theinterregnum up to the basal Ludlow (though outsideBritain this species seems to be almost confined to itsbiozone Porebska Kozłowska-Dawidziuk amp Masiak2004) Thus certain identification of this interregnumhinges on the recognition of the underlying or overlyingbiozone The nassadubius level has been subsequentlytreated and referred to as a biozone by most workersOther lsquointerregnarsquo have been recognized (eg a lowdiversity interval dominated by monograptids withhooked thecae in the upper turriculatus Biozone ofcentral Wales Davies et al 1997) and used informallySome well-established biozones also effectively com-prise low-diversity intervals separating more diverseand distinctive biozonal assemblages For example theuse of the peltifer Biozone in Scotland was definedon the basis of few incoming taxa but many speciesof the underlying gracilis Biozone are absent whilethose defining the overlying wilsoni Biozone have notyet appeared The difficulty of recognizing the peltiferBiozone led Williams et al (2004) to propose analternative biozonal arrangement for the lower Caradocinterval as discussed below

The duration of graptolite biozones has beenassessed in a number of ways Average duration isestimated by dividing radiometric estimates for theduration of periods or epochs by the number ofbiozones (eg Hughes 1995) Ordovician biozones aresignificantly longer averaging some 2 Ma (Rushton1990) than Silurian biozones which average lt 1 Maand lt 05 Ma if subzones and informal subdivisionsare taken into account (Zalasiewicz 1990) Within-period inequalities in length have been assessed byusing radiometric dates that constrain epoch ratherthan period boundaries in this way Hughes (1995)estimated average biozone durations respectively of10 044 10 and 143 Ma for the Llandovery WenlockLudlow and Prıdolı epochs Finer-scale estimates havebeen made by using thicknesses of distal deep-seagraptolitic mudrocks assuming sedimentation rates tobe roughly constant and cross-checking by comparingsections in different parts of the world and thenapplying radiometric age constraints In this wayChurkin Carter amp Johnson (1977) estimated the

persculptus Biozone as lt 1 Ma in duration while thegracilis Biozone apparently represents some 8 Ma

Some of the most precise correlation achievedhas been effected by bypassing the zonal conceptaltogether and cross-correlating the first and lastappearances of individual species in selected well-studied sections Cooper amp Lindholm (1990) used suchdata to effect graphical correlation of early to mid-Ordovician sections they showed that globally theappearances and disappearances of graptolites forma coherent pattern in time enabling subdivision intoabout 50 time-slices within a 20 Ma interval Furtherrefinement of this approach has involved for examplethe lsquoconstrained optimizationrsquo (CONOP) method de-scribed by Cooper amp Sadler (2004) that aimed atextracting the maximum information from individualspecies ranges and that further refined estimates of thedurations of individual biozones Within depositionalbasins or graptolite provinces such methodologiesshould see progessive advances in precision betweenprovinces endemism and diachronous species rangeswill limit progress

6 British graptoloid biostratigraphy a summary ofprevious work

Charles Lapworth (1878) first applied the concept ofgraptolite zones in Britain while working in the South-ern Uplands of Scotland Having examined a largenumber of sections and following the Swedish work ofLinnarsson (Hamilton 2001) he was able to subdividethe Hartfell and Birkhill Shale formations into elevenunits based on distinct lithological differences andfound that these corresponded with differences in theiraccompanying graptolite assemblages which he calledlsquozonesrsquo He provided detailed lithological logs of thebest sections as well as a chart outlining the verticalranges of all observed taxa from the sections studiedThis was to be the model of procedure for all futurebiostratigraphical work involving graptolites In thefollowing year Lapworth (1879ndash1880a) extended hisstudy of graptolite zones to include all British andinternational material identifying twenty zones for theLate Cambrian to Silurian interval He provided rangecharts for the graptolite genera and species then knownand suggested that these could form a basis for detailedtemporal subdivision of early Palaeozoic strata Hiswork was immediately put to the test by the GeologicalSurvey of Scotland and was found to be of the greatestvalue (Rushton 2001a)

These zones were recognizable in other parts ofBritain as later papers indicated notably in theStockdale Shales (Marr amp Nicholson 1888) and theSkiddaw Slates (Marr 1894) of the Lake DistrictKey biostratigraphical work in Wales and the WelshBorderland increased the number of known Britishgraptolite species and biozones Ellesrsquos (1900) studyof the Wenlock Shales of the Welsh BorderlandWoodrsquos (1900) on the Lower Ludlow Formation of theWelsh Borderland and Herbert Lapworthrsquos (1900) work



on the Silurian sequence at Rhayader in mid-Walesall provide detailed lithostratigraphies combined withspecies range charts new biozones were introduced andexisting ones altered reflecting distinct local variationsin the composition of the graptolite assemblages Wood(1900) subdivided part of the Ludlow succession atLong Mountain into subzones These workers alsocompared their range charts and faunal lists withinformation available from the rest of Britain andabroad particularly Sweden

lsquoA monograph of British graptolitesrsquo (Elles ampWood 1901ndash1918) is a complete account of all theBritish planktonic graptolite species and subspeciesknown at that time (apart from Rhabdinopora andCorynoides) providing descriptions and figures of eachtaxon The stratigraphical ranges of all the taxa werecollated into a biostratigraphy comprising 36 graptolitebiozones and subzones This was the first time that onestudy on British graptolites had unified the taxonomybiostratigraphy and chronostratigraphical importanceof the group to such an extent The monographcontinues to provide the basis for British graptolitebiostratigraphy and its influence on global correlationremains profound although many of the individualtaxon descriptions and ranges have been revised insubsequent studies

Graptolites were now established as a fundamentalpart of British Early Palaeozoic stratigraphical studies(eg Jones 1909 1947 Davies 1929 Jones amp Pugh1935) Later Sudbury (1958) beautifully demonstratedpatterns of fine-scale evolution in the Llandoverytriangulate monograptids of the Rheidol Gorge WalesToghill (1968a) updated the graptolite assemblages andbiozones of the early Silurian Birkhill Shale Formationof Scotland Studies on the Silurian strata of NorthernEngland included accounts of the Wenlock and Ludlow(Rickards 1967) and Llandovery (Rickards 1970)graptolites of the Howgill Fells and of the LakeDistrict (Hutt 1974ndash1975) The results of these studieswere collated into a major revision of British Siluriangraptolite ranges and zonal descriptions (Rickards1976) No corresponding update of Elles amp WoodrsquosOrdovician range charts was produced prior to theone we provide in this report although Jackson (1962)provided a synthesis of the Arenig biostratigraphy ofthe Skiddaw Group of the Lake District

Subsequent work includes Williamsrsquos descriptionsof the classic Dobrsquos Linn section (1982b 1988) whichbecame the OrdovicianndashSilurian boundary stratotype(Bassett 1985) and in the Moffat and Girvan districts(Williams 1982a 1987 1994) Zalasiewicz (19841986) described early Ordovician graptolite materialfrom North Wales and Fortey amp Owens (1978 1987)from South Wales

Major British Geological Survey (BGS) mappingprogrammes in Wales the Lake District and southernScotland were all underpinned by graptolite biostrati-graphy large collections were made and describedand the biozonation itself was considerably refinedRushtonrsquos (in Cooper et al 2004) reorganization

of Arenig graptolite biostratigraphy in the SkiddawGroup formed part of this work as did the report ofgraptolites of Arenig age in the Ballantrae ophiolitecomplex in SW Scotland (Stone amp Rushton 1983)Studies of younger Ordovician strata included those ofZalasiewicz (1992a) Zalasiewicz Rushton amp Owen(1995) Cave amp Rushton (1996) and Williams et al(2003a 2004) while the compilation of Scottishrecords by Rushton et al (1996) demonstrated thecontinued importance of graptolite work in the strati-graphy and structure of the Southern Uplands ofScotland

Remapping of central Wales by BGS promptedrefinement of Llandovery and Wenlock graptolitebiostratigraphy There were studies of early tomid-Llandovery (RhuddanianndashAeronian) sections andgraptolite assemblages (Zalasiewicz 1992b 1996Zalasiewicz amp Tunnicliff 1994) Spectacular progresswas made in late Llandovery (Telychian) successions(Loydell 1991a 1992ndash1993a 1993b Loydell amp Cave1993 1996 Zalasiewicz 1994 Zalasiewicz Loydellamp Storch 1995 Davies et al 1997) For examplethe former Monograptus turriculatus Biozone wassplit into two separate biozones each with severalcomponent subzones and the former Monoclimaciscrenulata Biozone into four separate biozones Work onEllesrsquos (1900) original Wenlock biozonal localities nearBuilth Wells (Zalasiewicz amp Williams 1999 Williamsamp Zalasiewicz 2004) resulted in a reorganization ofgraptolite biozones for that part of the stratigraphicalcolumn Nevertheless substantial sections of Britishearly Palaeozoic biostratigraphy remain relativelyneglected for example the Ludlow successions andfurther refinement may be expected The currentbiozonal schemes for the British Ordovician andSilurian are given in Figures 1 and 2

7 Notes on the range charts

Two separate graptoloid range charts are given forthe British Ordovician one representing England andWales (Figs 3ndash7) and the other Scotland (Figs 8ndash10)because significant regional differences in graptolitefaunas exist The separation of Scotland from Englandand Wales by the Iapetus Ocean resulted in faunalprovincialism during the Ordovician and for grap-tolites this remained the case even upon the closureof Iapetus at the end of the period probably as aresult of environmental factors (Zalasiewicz Rushtonamp Owen 1995) Fewer such problems exist in theSilurian and a single sequence of graptolite biozoneshas been recognized throughout the UK (Figs 11ndash19 )Sources for the ranges are provided (Tables 1ndash3) andfor ease of use an index to taxa (Table 4)

Elles amp Wood (1901ndash1918) assigned their speciesto relatively few genera There has since been anexpansion of generic concepts those used here mostlyfollow Strachanrsquos (1996ndash1997) review of Britishgraptolites Strachan gave full bibliographic referencesto the species known to him and those references are



Figure 3 For legend see facing page

not repeated here though references are given here forspecies recognized in Britain subsequent to Strachanrsquoscompilation

These range charts were commenced by JAZ andAWAR in work for the British Geological Surveysubstantially developed by LT during PhD studies

and subsequently added to by the other authorsSpecies recorded in the range charts have beenfully documented in papers monographs or memoirsRecords in conference abstracts are not included

In the range charts X ndash present A ndash abundant L ndashpresent in lower part M ndash present in middle part



Figure 3 Ordovician graptolites (a) and their stratigraphical ranges (b) in England and Wales flabelliformis to artus biozones Scalebar represents 10 mm except for 1 23 32 40 45 47 (20 mm) 3 4 6 7 9 10 15 23 37 42 (40 mm) 20 28 (57 mm) 33 (80 mm)and 48 (320 mm) Key to symbols used in range charts X ndash present A ndash abundant L ndash present in lower part M ndash present in middlepart U ndash present in upper part cf ndash similar to but not certainly identified aff ndash related to but not identical ndash doubtful ndash verydoubtful lt ndash range extends lower gt ndash range extends higher

U ndash present in upper part cf ndash similar to but notcertainly identified aff ndash related to but not identicalto named species ndash doubtful record ndash verydoubtful lt ndash range extends lower gt ndash range extendshigher

The thumbnail sketches of the graptolite taxaon the pages facing the charts are intended toremind the general reader of the overall characterof the various species They are not adequate foridentification




8 Ordovician

R A Cooper (1999) discussed the global correlationof Tremadocian graptolites recognized nine graptolitechronozones and in his figure 1 showed the rangesof the main types of graptolites in the TremadocianIn Britain only a few of those chronozones are

recognized They are distributed between two locallydefined stages proposed by Fortey et al (1995) theCressagian below and the Migneintian In Britain theupper Tremadocian is almost devoid of graptoliteswith two widely recognized trilobite biozones theConophrys salopiensis and Angelina sedgwickii zonesoccupying most of the Migneintian (Fig 1 3b)



Figure 4 Ordovician graptolites (a) and their stratigraphical ranges (b) in England and Wales simulans to gracilis biozones Scale barrepresents 10 mm except for 54 64 (20 mm) 53 57 63 70 (40 mm) For key to symbols in range charts see Figure 3

8a Rhabdinopora flabelliformis Biozone

The appearance of Rhabdinopora flabelliformis(formerly Dictyonema flabelliforme) has for a longtime been taken as a marker for the beginning

of the Tremadocian Although the base of the Or-dovician as currently defined is now taken at theappearance of the conodont Iapetognathus fluctivagus(Cooper Nowlan amp Williams 2001) the appear-ance of the earliest subspecies of Rhabdinopora




flabelliformis remains a good approximation to thebase of the Ordovician and is applicable in clasticsequences where conodonts are rare (Landing et al2000)

The lowest of Cooperrsquos biozones that of Rhabdino-pora praeparabola is not yet known in Britain

The flabelliformis Biozone in Britain appears toinclude the equivalents of Cooperrsquos parabola andmatanensis biozones and possibly part of the overlyinganglica Biozone At Brin-llin-fawr North Wales theoccurrence of taxa closely comparable to the early sub-species Rhabdinopora flabelliformis parabola and R f



Figure 5 Ordovician graptolites (a) and their stratigraphical ranges (b) in England and Wales cucullus Biozone to caudatus SubzoneScale bar represents 10 mm For key to symbols in range charts see Figure 3

desmograptoides at the base of the flabelliformisBiozone (Legrand in Rushton et al 1999 fig74) suggests that the parabola Biozone may proverecognizable Higher in the flabelliformis BiozoneR flabelliformis flabelliformis and R f socialis are

the most widely recognized forms and are knownfrom north Wales Shropshire and numerous boreholesin Warwickshire and Buckinghamshire (Bulman ampRushton 1973 Old Sumbler amp Ambrose 1987 Bridgeet al 1998) Although Rhabdinopora f anglica appears




to occur high in the flabelliformis Biozone it is notyet clear whether a separate anglica Biozone canbe recognized The borehole record of Kiaerograptusquasimodo Rushton 1981 is anomalous because it

lies in the midst of borehole records proving theflabelliformis Biozone (Old Sumbler amp Ambrose1987) whereas Kiaerograptus occurs typically in theequivalents of the Migneintian Stage



Figure 6 Ordovician graptolites (a) and their stratigraphical ranges (b) in England and Wales murchisoni to persculptus biozonesScale bar represents 10 mm For key to symbols in range charts see Figure 3

8b Adelograptus tenellus Biozone

This biozone is recognized by the appearance ofAdelograptus (formerly Clonograptus) tenellus and Ahunnebergensis Cooper (1999) recognized an Adelo-graptus Biozone above the Rhabdinopora flabelliformisanglica Biozone but these are not readily separated inBritain In the lsquoTransition Bedsrsquo of the Shineton Shalesof Shropshire Rhabdinopora flabelliformis subspp

including R f anglica alternate with Adelograptus sppthrough a relatively small thickness of strata abovewhich Rhabdinopora disappears It appears that anequivalent situation pertains to the English subcrop

8c Higher Tremadocian zones

Above the tenellus Biozone graptolites are practicallyabsent from strata in Britain until the top of the




Tremadocian and Migneintian biostratigraphy hasdepended on evidence from trilobites and acritarchsThere are however two records of Rhabdinoporaflabelliformis subspp from strata referred to theConophrys salopiensis trilobite Biozone as recognized

on the basis of trilobites and acritarchs one from theDeanshanger Borehole in Buckinghamshire (Bulmanamp Rushton 1973) the other from the lsquoUpper Dicty-onema Bandrsquo in the Gwynant Valley north of CadairIdris (Pratt Woodhall amp Howells 1995 p 16) Both



Figure 7 Ordovician graptolites (a) and their stratigraphical ranges (b) in England and Wales foliaceus to persculptus biozonesScale bar represents 10 mm For key to symbols in range charts see Figure 3

records presumably represent a late development ofCooperrsquos lsquoAssemblage 3rsquo (Cooper 1979) and pre-datehis P antiquus and Kiaerograptus biozones

8d Araneograptus murrayi Biozone

This biozone was first used in Britain by Cooperet al (1995) in reference to the Skiddaw Group from

the English Lake District The A murrayi Biozoneis currently the only recognizable upper Tremadociangraptoloid biozone in the British sequence The baseis taken on the appearance of the biozone fossilaccompanied by Acrograptus cf sinensis and a de-clined Didymograptus (sl) sp (Molyneux amp Rushton1988)




8e Tetragraptus phyllograptoides Biozone

The base of this biozone equates to that of theFloian Stage of the Ordovician (Bergstrom Lofgrenamp Maletz 2004) Cooper et al (1995) adopted the Tphyllograptoides Biozone an established Scandinavian

interval (Lindholm 1991) based on the similaritybetween the Skiddaw Group assemblages and thosecharacteristic of the upper part of this biozone inScandinavia (Maletz Rushton amp Lindholm 1991)The biozone fossil is not known from the LakeDistrict but this biozone may be recognized by the



Figure 8 Ordovician graptolites (a) and their stratigraphical ranges (b) in Scotland Lancefieldian 2 to wilsoni biozones Scale barrepresents 10 mm For key to symbols in range charts see Figure 3

appearance of Acrograptus protobalticus A rigolettoand Temnograptus multiplex Other taxa appearingare Tetragraptus quadribrachiatus and Tetragraptus(Pendeograptus) cf fruticosus Species diversity isstill relatively low in the phyllograptoides Biozonealthough greater than that of the previous biozone

and includes the first tetragraptids and a temnograptid(Fig 3) This interval has not been recorded elsewherein Britain (Cooper et al 1995 2004)

In Scotland graptoloid assemblages from the lowerto middle part of the Ordovician sequence resemblethose in Australasia more closely than the English and




Welsh assemblages This prompted Stone amp Rushton(1983) to use the Australasian graptolite biostratigraph-ical scheme (VandenBerg amp Cooper 1992) duringtheir work on the faunas of the Ballantrae ophiolitecomplex The earliest assemblages from Ballantraecontain Tetragraptus approximatus either by itself orassociated with T (Pendeograptus) fruticosus The

latter association is characteristic of the lowermostBendigonian (Be1) but the former could originate fromthe Lancefieldian (La3) Assemblages from Pinbainthat contain T cf decipiens Acrograptus cf filiformisand Paradelograptus sp are less definite but suggestan early Bendigonian (Be1ndash2) age (Rushton et al1986)



Figure 9 Ordovician graptolites (a) and their stratigraphical ranges (b) in Scotland gracilis to linearis biozones Scale bar represents10 mm For key to symbols in range charts see Figure 3




8f Corymbograptus varicosus Biozone

Following recent revision of Skiddaw Group grap-toloid biostratigraphy (Cooper et al 1995) the Cvaricosus Biozone has replaced the previously used

Corymbograptus deflexus Biozone (Jackson 1978Fortey amp Owens 1990) Cooper et al (1995 2004)found C deflexus to be rare in this interval whereas Cvaricosus is abundant There is no clear definition forthe base of the varicosus Biozone due to the lack of



Figure 10 Ordovician graptolites (a) and their stratigraphical ranges (b) in Scotland caudatus Subzone to persculptus Biozone Scalebar represents 10 mm For key to symbols in range charts see Figure 3

known suitable fossiliferous strata in the Lake District(Rushton et al 1999 p 266 Cooper et al 2004p 13) This assemblage displays a marked increase inspecies and generic diversity New appearances include

Baltograptus vacillans attenuatus Didymograptus affbalticus Tetragraptus reclinatus T (P) fruticosusExpansograptus cf decens and Acrograptus filiformisSome species are known only from the upper part




of the biozone C deflexus Pseudophyllograptusangustifolius Dichograptus octobrachiatus sedgwickiiSchizograptus tardifurcatus and Expansograptus cfsimilis (Fig 3)

8g Expansograptus simulans Biozone

This biozone straddles the interval between thelsquosecondrsquo (Floian) and lsquothirdrsquo (Dapingian) stages of

the Ordovician (Cooper amp Sadler 2004) The formerDidymograptus nitidus Biozone was renamed on thebasis that the former zone fossil does not occur inthis interval in the Skiddaw Group (Cooper et al1995) The base of the biozone is defined on theincoming of Expansograptus simulans and Acrograptusinfrequens (Cooper et al 1995 Rushton in Cooperet al 2004) A significant rise in graptolite diversitycan be seen at this horizon with about 33 taxa



Figure 11 Silurian graptolites (a) and their stratigraphical ranges (b) in Great Britain ascensusndashacuminatus to sedgwickii biozonesScale bar represents 10 mm For key to symbols in range charts see Figure 3

recorded (Fig 3) Several new forms are confinedto this biozone including Didymograptus minutusTetragraptus postlethwaitei Adelograptus divergensand Tetragraptus (Pendeograptus) pendens Othernoteworthy appearances are Azygograptus eivionicusAzygograptus lapworthi Pseudobryograptus cumbren-sis Acrograptus kurcki Loganograptus logani and

Tetragraptus crucifer Cooper et al (1995) suggestedthat the presence of Isograptus cf primulus in thisinterval indicates a correlation with the ChewtonianStage (Ch 1ndash2)

The contemporaneous Scottish taxa differ markedlyfrom those of England and Wales with the exceptionof Tetragraptus serra and Tetragraptus reclinatus




which occur in both successions (Fig 8) Stoneamp Rushtonrsquos (1983) work at Ballantrae revealedgraptolite assemblages containing Didymograptus cfprotomurchisoni Tetragraptus bigsbyi cf askerensisExpansograptus aff geometricus Didymograptus cfprotoindentus Sigmagraptus praecursor Paradelo-graptus sp Tetragraptus (P) fruticosus and Tetragrap-

tus cf kindlei which they found consistent with aChewtonian age

8h Isograptus victoriae victoriae Biozone

The recognition of distinct biostratigraphically import-ant graptolites within the old Isograptus gibberulus



Figure 12 Silurian graptolites (a) and their stratigraphical ranges (b) in Great Britain atavus Biozone to gemmatus Subzone Scalebar represents 10 mm For key to symbols in range charts see Figure 3

Biozone of the Skiddaw Group led to the proposal ofa lower I victoriae victoriae Biozone and an upper Igibberulus Biozone (Rushton in Cooper et al 2004p 17) The I v victoriae Biozone is characterized bythe appearance of the zone fossil which is confinedto this interval However the index species is rare inthe Lake District leading to difficulties in identifyingthe biozonal boundaries Horizontal didymograptidssuch as Expansograptus hirundo E cf nitidus andE extensus linearis help to characterize the victoriaeand gibberulus biozones Other forms limited to

the victoriae Biozone are Phyllograptus densus andIsograptus victoriae cf maximus while the appearanceof E hirundo and E cf nitidus (Figs 3 4) is recordedin the Shelve area of Shropshire (Strachan 1986)

No graptolite assemblage corresponding to thisinterval has been reported from Scotland (Fig 8)

8i Isograptus gibberulus Biozone

This biozone as restricted by Rushton (in Cooperet al 2004 p 17) in the Skiddaw Group of the




English Lake District is defined by the appearanceof I gibberulus Cooper et al (1995) suggestedthat the former I gibberulus Biozone equated withthe Australasian Castlemainian Stage (Ca 1ndash4) butas now restricted it represents the upper part ofthe Castlemainian (Ca 3ndash4) (Cooper et al 2004)The identification of Pseudisograptus dumosus atthis horizon from the Aberdaron area of Wales andIsograptus caduceus cf imitatus from Grisedale Pike

in the Lake District (Jenkins 1982) seems to confirmthis Other noteworthy appearances include Pseudiso-graptus angel Corymbograptus v-fractus volucer Tet-ragraptus bigsbyi bigsbyi Corymbograptus uniformisand Xiphograptus svalbardensis (Fig 4)

In Scotland an assemblage obtained from the NorthBallaird Borehole in the Ballantrae ophiolite complexcontained elements comparable to those for this intervalin England and Wales (Stone amp Strachan 1981)



Figure 13 Silurian graptolites (a) and their stratigraphical ranges (b) in Great Britain triangulatus Biozone to utilis Subzone Scalebar represents 10 mm For key to symbols in range charts see Figure 3

but also other taxa (Arienigraptus gracilis Isograptuscaduceus australis Tylograptus and Yutagraptus v-deflexus) that indicate a latest Castlemainian or earlyYapeenian age (Stone amp Rushton 2003) (Fig 8) In

a review of this assemblage Maletz (2004) referredthe supposed A gracilis to Pseudisograptus initialisMaletz 2001 and the Tylograptus to a species ofMeandrograptus However although Stone amp Rushton




(2004) gave reasons for rejecting the transfer oftheir specimens of I caduceus australis to Isograptuscaduceus imitatus they accepted Maletzrsquos suggestionthat the North Ballaird assemblage is best restricted tothe late Castlemainian (Ca4)

As yet no graptolite assemblages have been reportedfrom Scotland at a higher stratigraphical level untilthe base of the Nemagraptus gracilis Biozone at thebase of the Sandbian Stage (base of Upper Ordovician)(Fig 8)



Figure 14 Silurian graptolites (a) and their stratigraphical ranges (b) in Great Britain convolutus Biozone to galaensis Subzone Scalebar represents 10 mm For key to symbols in range charts see Figure 3

8j Aulograptus cucullus Biozone

The base of the cucullus Biozone equates with thatof the Darriwilian Stage (Cooper amp Sadler 2004)Rushton (in Cooper et al 2004 p 19) renamedthe former Didymograptus hirundo Biozone the

Aulograptus cucullus Biozone to take into accountthe fact that Expansograptus hirundo originatesmuch earlier in the victoriae Biozone The base of thecucullus Biozone is characterized by the incoming of Acucullus and many other taxa originate in the biozoneamong them the first cryptograptids Oelandograptus




austrodentatus anglicus Acrograptus nicholsoniplanus Didymograptus protobifidus Expansograptussparsus Undulograptus cumbrensis U sinicus and Eo-glyptograptus shelvensis these include the first biserialgraptolites in the British Ordovician sequence (Fig 4)Assemblages of the A cucullus Biozone have also

been recorded from the Shelve district of Shropshire(Strachan 1986) The range chart shows a fewtaxa indicating the upper part of this biozone(Fig 5) these are Acrograptus acutidens and possiblyAmplexograptus confertus and Cryptograptus tricornisschaeferi



Figure 15 Silurian graptolites (a) and their stratigraphical ranges (b) in Great Britain runcinatus Subzone to crenulata Biozone Scalebar represents 10 mm For key to symbols in range charts see Figure 3

8k Didymograptus artus Biozone

The base of the D artus Biozone corresponds withthat of the locally defined Llanvirn Series Thebiozone was established by Fortey amp Owens (1987) toreplace the traditional Didymograptus bifidus Biozone

which was based on incorrect identifications Thisinterval displays a highly diverse and distinctivegraptolite assemblage (Fig 5) with the majority oftaxa appearing at the base of the biozone which ischaracterized by the zone fossil and Didymograptusspinulosus (Fortey amp Owens 1987 Fortey Beckly




amp Rushton 1990 Rushton in Cooper et al 2004)Approximately 31 species originate in the biozone 21of which have ranges restricted to it Several generaare recorded for the first time notably Glossograptusand Climacograptus The artus Biozone has goodpotential for further biostratigraphical subdivisionWhile most elements of the assemblage span the entire

biozone there is a distinguishable middle to upperbiozonal assemblage containing Pseudoclimacograp-tus scharenbergi P angulatus Trichograptus fragilisDiplograptus hollingworthi and Nicholsonograptusfasciculatus (Fig 5) A few taxa help differentiatethe lower part of the biozone such as D protobifidusand Expansograptus sparsus which originate in the



Figure 16 Silurian graptolites (a) and their stratigraphical ranges (b) in Great Britain proteus Subzone to riccartonensis BiozoneScale bar represents 10 mm For key to symbols in range charts see Figure 3

cucullus Biozone but disappear in the lower part ofthe artus Biozone The D artus Biozone has beenwidely recognized in northern England and Wales(Elles 1940 Strachan 1986 Fortey amp Owens 1987Fortey Beckly amp Rushton 1990 Cooper et al 19952004)

8l Didymograptus murchisoni Biozone

Graptolite assemblages characteristic of this biozonehave been recorded from the BuilthndashLlandrindod Wellsdistrict of central Wales (Elles 1940 Hughes 1989Davies et al 1997) the Shelve area of Shropshire




(Strachan 1986 Hughes 1989) the Skiddaw Groupstrata of the Tarn Moor Tunnel in the Lake District(Wadge Nutt amp Skevington 1972) the Fishguardarea of South Wales (Davies et al 2003) andAbereiddy Bay (Jenkins 1987) The base of themurchisoni Biozone sees the incoming of the zonefossil which is restricted to this biostratigraphicalinterval (Fig 5) Other new appearances include

Diplograptus foliaceus Cryptograptus tricornis tri-cornis Pseudoclimacograptus angulatus magnus Pangulatus micidus and Didymograptus speciosus(Fig 5) Pterograptus elegans Lasiograptus retususand Didymograptus nanus are reported only fromthe lower part of the biozone whereas Diplograptusdecoratus Amplexograptus caelatus and Normalo-graptus brevis appear in its middle to upper part this



Figure 17 Silurian graptolites (a) and their stratigraphical ranges (b) in Great Britain spiralis to ludensis biozones Scale bar represents10 mm For key to symbols in range charts see Figure 3

suggests that refinement of the biostratigraphy may bepossible

8m Hustedograptus teretiusculus Biozone

The base of this biozone is delineated by the dis-appearance of D murchisoni (Hughes 1989) as the

zone fossil originates in the middle part of the interval(Fig 6) The lower part of the biozone therefore isan interregnum The only taxa to appear at the basalboundary are Dicellograptus divaricatus divaricatusClimacograptus antiquus and possibly Normalograptuseuglyphus Approximately half of the total speciesoccurring at this biostratigraphical level appear in




the middle to upper part of the biozone These dataprovide a strong case for a biostratigraphical review ofthe graptolite faunas found in this interval HoweverHughes (1989) remarked that Ellesrsquos (1940) attemptto subdivide the teretiusculus and gracilis biozones inthe Builth area was incorrect as her refinement wasbased on taxonomically unsound species and poorlypreserved material The teretiusculus Biozone as it

is presently understood is recorded from Wales andShropshire (Elles 1940 Strachan 1986 Hughes 1989Davies et al 1997)

8n Nemagraptus gracilis Biozone

The base of this biozone equates with that of theSandbian Stage of the Ordovician (Cooper amp Sadler



Figure 18 Silurian graptolites (a) and their stratigraphical ranges (b) in Great Britain dubius to bohemicus biozones Scale barrepresents 10 mm For key to symbols in range charts see Figure 3

2004) or with that of the Caradoc of British usage Thisbiostratigraphic interval was first described by Lap-worth (1879ndash1880) and defined by the incoming of thedicellograptids and nemagraptids Subsequent work ledto a revised definition of the base of the biozone whichis now taken at the incoming of N gracilis (Finneyamp Bergstrom 1986) Assemblages representing thisbiozone have been recorded from the Builth region

of Wales and the Shelve area of the Welsh Borderland(Elles 1940 Strachan 1986 Hughes 1989 Davieset al 1997) However although the position of thebase of the gracilis Biozone at Builth Wells is unclear(Hughes 1989 Davies et al 1997) Bettley Fortey ampSiveter (2001) have identified a correlatable base to thebiozone west of Shelve and at Meidrim south WalesThe Anglo-Welsh N gracilis assemblage is diverse



Figure 19 Silurian graptolites (a) and their stratigraphical ranges (b) in Great Britain scanicus to bohemicus biozones Scale barrepresents 10 mm For key to symbols in range charts see Figure 3

containing some 26 incoming species as well as manylonger-ranging forms from underlying zones (Fig 6)Several species appear in the upper part of the biozoneand although only one of these Lasiograptus pusillusseems limited to this level this assemblage maypotentially be biostratigraphically useful Incomingupper zonal taxa include Climacograptus bicornis Di-cranograptus nicholsoni nicholsoni Amplexograptusperexcavatus and Glossograptus hincksii hincksii

Graptolites reappear dramatically in the Ordovi-cian sequence of Scotland in the gracilis BiozoneFollowing the sparse low-diversity assemblages ofthe Scottish lower to middle Arenig interval ofBritish usage and the absence of Llanvirn biozonesa varied and abundant graptolite assemblage of Ngracilis age (about 75 taxa) has been recorded fromsouthern Scotland (Stone 1995 Rushton Tunnicliff ampTripp 1996 Armstrong et al 1998 Williams et al2004) including the Girvan district (Rushton 2001b)From this biozone upwards the Scottish graptolitesuccession is more directly comparable to that ofEngland and Wales than in the Lower Ordovicianalthough the two biostratigraphical schemes still reflectsignificant assemblage differences (Fig 1) makingprecise correlation difficult (Zalasiewicz Rushton ampOwen 1995 Williams et al 2004) In Scotland thegracilis Biozone is similarly defined as in Englandand Wales although Stone (1995) commented onthe importance of Expansograptus superstes andDicellograptus intortus to the characteristic gracilis

assemblage (Figs 8 9) D intortus appears lower inthe Anglo-Welsh sequence however and the exactposition of the base of the gracilis interval cannot beclearly recognized in Scotland (Rushton 1990 see alsoWilliams et al 2004) Recent work by Williams et al(2004) has restricted the gracilis Biozone as outlinedin the next section

8o Diplograptus foliaceus Biozone

The D foliaceus Biozone is an Anglo-Welsh biostrati-graphical unit traditionally employed for the graptoliteassemblages found between those of the underlyinggracilis Biozone and the Dicranograptus clinganiBiozone above (Fig 1) It was formerly known asthe Diplograptus multidens Biozone however thetaxonomic validity of D multidens has been questioned(Hughes 1989) and we follow Bettley Fortey ampSiveter (2001) in naming the biozone after its suggestedsenior synonym D foliaceus Much of Elles ampWoodrsquos (1901ndash1918) and Ellesrsquos (1940) earlier workon this biozone from the Shelve inlier and the typesections of the Caradoc area of Wales must be treatedwith caution as many of the original taxa have notbeen found following recent studies (Hughes 1989)Nonetheless work carried out by the BGS in centralWales has confirmed the existence of a distinct andstratigraphically useful foliaceus Biozone assemblage(Figs 6 7) with several newly occurring taxa (Davieset al 1997 Williams et al 2003a) An upper biozonal



Figure 20 Comparison of presently adopted and earlier Scottishzonal schemes for the gracilis to clingani biozonal interval

assemblage with biostratigraphical potential has beenidentified (Fig 7) including Dicranograptus nicholsoniminor and Dicellograptus patulosus

8p Climacograptus bicornis Biozone (in Scotland)

Williams et al (2004) recently formalized the useof this zone for Scottish strata having reviewed allthe Scottish early Caradoc graptolite assemblagespreserved from the 19th century geological survey ofsouthern Scotland (Peach amp Horne 1899) and fromthe work of the British Geological Survey during the1980s and 1990s The bicornis Biozone correspondsto the range of Climacograptus bicornis commencingwith its appearance in the N gracilisndashC bicornis faunasfrom the Glenkiln Shales (in beds that were formerlyassigned to the gracilis Biozone) and ranging up almostto the base of the Dicranograptus clingani Biozone inthe lower Hartfell Shales (S H Williams 1994) MWilliams et al (2004) divided the bicornis Biozoneinto two subzones the apiculatusndashziczac Subzone andthe wilsoni Subzone (Fig 20) as described below

Formerly two zones were recognized in the Scottishstrata that follow the last appearance of Nemagraptusgracilis and precede the advent of the Dicranograptusclingani Biozone these were known as the Cli-macograptus peltifer and C wilsoni biozones Thereare problems with the recognition of the C peltiferBiozone partly because the validity of the index speciesis doubtful (Strachan 1971 Riva 1976) and alsobecause the original supposedly diagnostic peltiferassemblage (Elles 1925) is much less diverse thanthe underlying N gracilis-bearing assemblages andcontains few elements that do not occur in the gracilisBiozone (Rushton 1990 Williams et al 2004) Thelong-recognized wilsoni Biozone is more distinctivewhere it is found but is of relatively local occurrenceand is not widely recorded Williams et al (2004)reduced it to a subzone of the bicornis Zone

The correlation of the zonal units in the gracilis toclingani interval is not a simple one-to-one correlationbecause in the new arrangement the gracilis Biozonehas a reduced stratigraphical range characterized bythe range of N gracilis below the first appearance ofC bicornis The upper and better-known assemblages(eg from the Glenkiln Shale) that were formerlyassigned to the gracilis Biozone are now referred tothe lower part of the bicornis Subzone namely theapiculatusndashziczac Subzone (see Figs 8 9)

8p1 Orthograptus apiculatusndashDicranograptus ziczacSubzone (in Scotland)

This subzone is recognized by the first appearances(FADs) of a large number of taxa Williams et al (2004fig 2) listed about 40 that first appear at about this levelthough because good measured sections are lackingthe FADs are not claimed to be precisely synchronousThe subzone is named after two distinctive species thatare fairly widely recorded (Williams et al 2004 p101) and have similar ranges The apiculatusndashziczacSubzone differs significantly from the peltifer Zone aspreviously used because N gracilis is present in itslower part together with such taxa as Dicranograptusfurcatus minimus Expansograptus superstes andHallograptus spp The assemblages in the lower part ofthe apiculatusndashziczac Subzone in which the range of Ngracilis overlaps with those of C bicornis and the taxanamed above are well known from the Glenkiln Shalesof southern Scotland and were formerly assigned to theextended concept of the N gracilis Biozone The upperpart of the apiculatusndashziczac Subzone above the rangeof N gracilis is a weakly characterized interval thatmay at least in part correspond to the peltifer Biozone(Williams et al 2004 p 105) and such faunas havebeen recorded in the higher Glenkiln Shales

8p2 Climacograptus wilsoni Subzone (in Scotland)

Lapworth (1878 p 308) established the C wilsoniBiozone during his work on the Moffat Series of theSouthern Uplands and it remains a recognizable partof the Scottish biostratigraphical scheme (Williams1994) although it has not been recognized elsewhere inGreat Britain (Elles amp Wood 1901ndash1918 Elles 19251937) However a taxonomic and biostratigraphicalreview of the wilsoni Biozone by Williams (1994)confirmed the value of this graptolite assemblage insouthern Scotland A type section was designated atHartfell Spa (Williams 1994) and the biozone hasbeen recognized elsewhere (Stone 1995 Williams1994) The wilsoni assemblage has fewer taxa thanthe lsquopeltifer assemblagersquo and many of them continuefrom the lower biozone (Fig 9) The base of the Cwilsoni Biozone is defined by the appearance of theindex species other incoming taxa are Orthograptuscalcaratus vulgatus Corynoides curtus C calicularisDicellograptus angulatus and Orthograptus of theamplexicaulis group

8q Dicranograptus clingani Biozone

The D clingani Biozone was established in the Moffatarea by Lapworth (1878 p 308) and has been widelyrecognized in Scotland (Williams 1982a Stone 1995Floyd 1999) and also in Wales (Davies et al 1997Howells amp Smith 1997 Young Gibbons amp McCarroll2002 Williams et al 2003a) Work at Hartfell Scorein the Southern Uplands of Scotland and Whitland insouth Wales led Zalasiewicz Rushton amp Owen (1995)



to erect two subzones within the clingani intervalclearly defined by distinct graptolite assemblagesand recognizable in both regions (Fig 1) althoughthere is some variation in assemblage composition(Zalasiewicz Rushton amp Owen 1995) The potentialfor subdivision of the biozone in the Southern Uplandshad previously been remarked on by Williams (1982a)

8q1 Ensigraptus caudatus Subzone

The base of this subzone is defined by the incomingof the index species at Hartfell Score with a largeassemblage of other forms (Zalasiewicz Rushton ampOwen 1995) The base of this subzone also defines thatof the Katian Stage of the Ordovician (Cooper amp Sadler2004) D clingani is restricted to the caudatus Subzonein both Wales and Scotland (Zalasiewicz Rushton ampOwen 1995 Davies et al 1997 Figs 7 9) In NorthWales the caudatus Subzone is present in the Nod GlasFormation (Pratt Woodhall amp Howells 1995 p 49Young Gibbons amp McCarroll 2002 p 53) InSouth Wales the assemblage contains similar elementsto those found in the Southern Uplands such asOrthograptus quadrimucronatus and Climacograptusspiniferus However E caudatus itself has beenrecognized in this region only in the LlanilarndashRhayaderarea (Davies et al 1997) and doubtfully from Cardigan(Williams et al 2003a) Overall the caudatus Subzoneassemblages of Wales with about 28 taxa present areless diverse than those of Scotland in which about 46taxa are known

8q2 Dicellograptus morrisi Subzone

In Wales and Scotland the D morrisi Subzone hasa large and diverse graptolite assemblage but fewerincoming species than the underlying E caudatus Sub-zone (Figs 7 10) At Hartfell Score southern ScotlandZalasiewicz Rushton amp Owen (1995) described thisinterval as a partial-range subzone the base beingdefined by the appearance of D morrisi and the topby the incoming of the linearis Biozone assemblageAt Whitland South Wales the base of the subzonewas delineated by the incoming of Normalograptusangustus (Perner 1895) (likely a senior synonymof Climacograptus miserabilis Loydell 2007) andpossibly D morrisi the range of which is limited tothis subzone (Zalasiewicz Rushton amp Owen 1995)lsquoGlyptograptusrsquo daviesi is the only incoming speciesdefinitely reported from the base of the morrisi Subzonein Wales (Fig 7) but in Scotland several taxa (besidesthe zone fossil) appear including Normalograptus mo-hawkensis Climacograptus dorotheus Dicellograptuscaduceus and Leptograptus flaccidus spinifer (Fig 10)Davies et al (1997) did not identify a discrete upperclingani Biozone assemblage in central Wales but it ispresent in the Nod Glas of North Wales (Pratt Woodhallamp Howells 1995 p 49) and in coastal sections west ofCardigan Williams et al (2003a) found that the morrisiSubzone was better represented than the underlyingcaudatus Subzone

8r Pleurograptus linearis Biozone

The original work on the graptolite assemblage ofthis interval was carried out by Lapworth (1878) onthe upper part of the Lower Hartfell Shales in theSouthern Uplands Williams (1982a) has undertakenthe only comprehensive study of the P linearisBiozone in this area since Elles amp Woodrsquos (1901ndash1918) review of British graptolites though Toghill(1970b) redescribed some of the fauna Williams(1982a) was able to delineate the base of the biozonefor the first time in the North Cliff section of DobrsquosLinn and designated it as the type section for theinterval base Taxa diagnostic of the base include thezone fossil with Climacograptus tubuliferus possiblyClimacograptus styloideus and Leptograptus flacci-dus macilentus however several forms appear mid-biozone including Amphigraptus divergens divergensLeptograptus capillaris and Dicellograptus eleganselegans (Fig 10) The overall assemblage is quitediverse in Scotland most species continuing fromunderlying biozones Graptolites characteristic of thisbiostratigraphical interval have been reported in theRhins of Galloway southwest Scotland (Stone 1995)and at many sites along-strike to the NE (Floyd1999 McMillan 2002) including Hartfell Score inthe Moffat district (Zalasiewicz Rushton amp Owen1995) Floyd (1999) recorded the linearis Biozone inthe Girvan succession

At Whitland in south Wales a low-diversity grap-tolite assemblage possibly equating (at least in part)with the P linearis Biozone was recognized byZalasiewicz Rushton amp Owen (1995) the base ofwhich marks the appearance of large normalograptidsThey referred to this biozone as the lsquoNormalograptusproliferation intervalrsquo Davies et al (1997) did notrecord any linearis Biozone assemblages from theLlanilarndashRhayader area but Williams et al (2003a)recognized equivalents of the linearis Biozone atFrongoch southwest of Cardigan and records ofClimacograptus styloideus at Llanystumdwy suggestthat the linearis Biozone may be present in NorthWales (Harper 1956) Exact correlation between thebase of the Ashgill Series as defined in the UK and theBritish graptolite biostratigraphical sequence cannot asyet be made as the Welsh record is poor and the LowerAshgill of Scotland is rarely graptolitic (Rushton1990) The linearis Biozone currently spans the BritishCaradocndashAshgill boundary as the lower part of thebiozone is believed to correlate with the uppermostCaradoc Onnian Substage (see Fig 1 Ingham 1966Ingham amp Wright 1970) Rickards (2002) describedseveral species referable to the linearis Biozone fromstrata as high as the upper Rawtheyan (shelly zone 6)in the typical Ashgill succession of the Cautley districtnorthern England (see below)

8s Dicellograptus complanatus Biozone

The D complanatus Biozone is another graptoliteassemblage biozone initally recognized in the Southern



Uplands of Scotland (Dobrsquos Linn) by Lapworth (1879ndash1880a) but rarely recognized since The work ofWilliams (1987) on strata representing this intervalfrom the Moffat and Girvan areas has resulted ina greater understanding of the complanatus Biozoneassemblage although the upper and lower limits ofthe biozone cannot be precisely delineated as thefossiliferous beds lie within strata barren of graptolitesThe assemblage is of low diversity and consistsmainly of species confined to this level including thezone fossil and Dicellograptus alector Orthoretiolitespulcherrimus Dicellograptus minor and Glyptograptusoccidentalis Longer-ranging species occur such asNormalograptus angustus (= Climacograptus miser-abilis of older literature) and C tubuliferus (Fig 10)

The complanatus Biozone has not been conclusivelyproven to occur in Wales (Rushton 1990) and nodiagnostic complanatus Biozone species have beenrecovered There is no graptolitic evidence for the com-planatus Biozone in northern England indeed thereis scarcely space to accommodate it Rickards (20022004) placed graptolites from shelly zone 6 (upperRawtheyan) of the type Ashgill section Backside BeckCautley northern England (Ingham 1966 Ingham ampWright 1970) in the linearis Biozone and recordedgraptolites from shelly zone 7 that could representthe complanatus or the anceps graptolite BiozoneIn the Girvan area however beds that are correlatedwith shelly zone 7 have yielded Paraorthograptuspacificus the index species of the upper subzoneof the anceps Biozone (Floyd Williams amp Rushton1999) The suggestion by Elles (1925 p 343) that thecomplanatus Biozone was lsquoa sub-zone of the P lineariszone rsquo possibly representing special environmentalconditions might bear renewed examination

8t Dicellograptus anceps Biozone

Lapworth introduced the D anceps Biozone for thegraptolite assemblages of the uppermost Hartfellstrata in the Moffat area (Lapworth 1878 p 316) Ataxonomic and stratigraphical review of this intervalwas undertaken by Williams (1982b) who was ableto subdivide the biozone into two subzones a lowerDicellograptus complexus Subzone and an upperParaorthograptus pacificus Subzone The base of theD complexus interval is marked by the incoming ofD complexus and D anceps The subzone possesses arelatively small but distinct graptolite assemblage withDicellograptus minor and Normalograptus angustus(= N miserabilis) continuing from the previousbiozone New appearances include Anticostia fastigataAppendispinograptus supernus Normalograptusnormalis and Pleurograptus lui (Fig 10) whileOrthograptus abbreviatus is abundant The upperpart of the complexus Subzone is characterizedby the incoming of Amplexograptus latus andOrthoretiograptus denticulatus The overlying Ppacificus Subzone has a slightly more diverseassemblage consisting of the same taxa from theunderlying complexus Subzone with the addition at

the base of P pacificus Nymphograptus velatus andPlegmatograptus lautus (Fig 10) Stone (1995) notedanceps Biozone assemblages in southwest Scotlandand there are several records along-strike to the NE(McMillan 2002)

Graptolites of probable D anceps Biozone age havebeen recorded in Wales although no potential forsubdivision has been reported (Davies et al 1997)Taxa present include App supernus N normalis andO abbreviatus (Fig 7) while D anceps itself has beenrecorded at Nant-y-moch (Jones 1909 Cave amp Hains1986) The anceps Biozone may be present in the northof England but is not proved

8u Normalograptus extraordinarius Biozone

This biozone recognized in Scotland but not inEngland and Wales because of a lack of graptolitic(anoxic) strata sees the incoming of Normalograptusextraordinarius and Normalograptus pseudovenustuscf pseudovenustus At Dobrsquos Linn this appears in BandE formerly placed in the anceps Biozone (Williams1986) where it overlaps with the latest appearancesof taxa such as Dicellograptus anceps D ornatusAppendispinograptus supernus and Paraorthograptuspacificus Above this a very thin black bed between thehighest bed of the anceps Biozone and the base of thepersculptus Biozone was termed the Climacograptusextraordinarius Band (Ingham 1979 Williams 19831986 1988) the graptolite assemblage in this is smallcomprising only the zonal fossil with Climacograptussp indet and Glyptograptus sp indet

8v Normalograptus persculptus Biozone

This biozonal assemblage was originally subdividedfrom the lower part of the acuminatus Biozone byJones (1909) at Pont Erwyd central Wales Theinterval has since been recognized throughout theUK (Davies 1929 Toghill 1968a Rickards 19701976 Hutt 1974ndash1975 Williams 1988 Stone 1995p 11 McMillan 2002 p 24) where it equates tothe local Hirnantian The persculptus Biozone is nowaccepted as the highest graptolite assemblage biozoneof the Ordovician in the UK biostratigraphical schemeIndeed work on the synonomy of N persculptusand lsquoGlyptograptusrsquo bohemicus led Storch amp Loydell(1996) to recommend that the base of the persculptusBiozone could be further extended to include anextraordinarius Subzone The base of the interval istaken at the appearance of N persculptus other incom-ing species include Glyptograptus avitus Atavograptusceryx N parvulus N medius and lsquoClimacograptusrsquotuberculatus (Figs 7 10)

9 Silurian

9a Akidograptus ascensusndashParakidograptus acuminatusBiozone

This is the basal Silurian graptolite biozone of theBritish succession Charles Lapworth (1878 p 318)



originally recognized it as such and named it theDiplograptus acuminatus Zone although Lapworthrsquos(and Elles amp Woodrsquos 1901ndash1918) concept of thisbiozone embraced also the underlying persculptusBiozone It is the lowest of six biozones that Lapworthbased on the Birkhill Shale Formation succession atDobrsquos Linn in southern Scotland

The base of the biozone is marked by the in-coming of Akidograptus ascensus and Parakidograp-tus acuminatus praematurus and 16 m higher ofParakidograptus acuminatus acuminatus (MelchinCooper amp Sadler 2004) The assemblage as a wholeis dominated by biserial graptolites (Fig 11) Someof the commonest taxa (Normalograptus normalis Nmedius N angustus) range up from the persculptusBiozone and these are joined by newcomers such asNeodiplograptus modestus sl and Ne diminutus Re-cords of typically Ordovician taxa most notably thoseof orthograptids of the truncatus group (Hutt 1974ndash1975 Rickards 1976) have not been substantiated bylater work

The only monograptid known is Atavograptus ceryxreported as coming up from the persculptus Biozoneand rarely recorded (in Scotland) from this interval(Hutt 1974ndash1975 Rickards 1976) though reportedby Harper amp Williams (2002) as appearing in theascensus Biozone Normalograptus persculptus hasbeen recorded into the upper part of the biozone(Davies 1929 Zalasiewicz amp Tunnicliff 1994 Davieset al 1997 but see Loydell 2007)

Informal subdivision of the ascensusndashacuminatusBiozone has been made (Rickards 1976 Zalasiewiczamp Tunnicliff 1994 Davies et al 1997) and in somestudies a formal distinction has been made (eg Ronget al 2007) A ascensus is generally more abundant inand P acuminatus praematurus is confined to the lowerpart of the biozone with P a acuminatus appearinghigher and being more common in the upper part(Toghill 1968a Hutt 1974ndash1975 see also Loydell2007) Atavograptus ceryx has been recorded only inthe lower part (though presumably there must be somelink between A ceryx and later atavograptids whichappear in the succeeding atavus Biozone) The middleof the biozone has been recognized by the presenceof the distinctive short-ranged species Normalograptustrifilis Although Cystograptus vesiculosus has alsobeen recorded as low as the middle of the biozone (egRickards 1976 McMillan 2002 appendix 1 loc 48)these records seem to represent C ancestralis (Storch1996) at least in part (M Melchin pers comm) Thefirst record of N rectangularis is in the upper part ofthe biozone

9b Atavograptus atavus Biozone

Herbert Lapworth (1900) originally referred to this unitas the Monograptus tenuis lsquoZonersquo from the RhayaderDistrict of Central Wales He recorded the assemblageof lsquoM tenuisrsquo Climacograptus scalaris normalis andC rectangularis However Lapworthrsquos zonal species

had been misidentified and Jones (1909) renamed thezone the Monograptus atavus Zone

From 19 taxa recorded in the ascensusndashacuminatusBiozone the number in the atavus Biozone increasesto approximately 30 (Fig 11) The essential featureof this biozone is the radiation of monograptid anddimorphograptid taxa The incoming of Atavograptusatavus defines the base of the biozone and A gracilisand Huttagraptus praematurus appear at more or lessthe same level Pribylograptus cf incommodus appearshigher in the biozone The dimorphograptids appearto form a useful temporal succession thus Rhaph-idograptus extenuatus and Dimorphograptus elongatusappear at or near the base of the biozone whilelater newcomers include Dimorphograptus confertusconfertus Dimorphograptus decussatus decussatusDimorphograptus longissimus and Dimorphograptusepilongissimus (see Hutt 1974ndash1975) the commonand long-ranging Rhaphidograptus toernquisti ori-ginates near the top of the biozone This suggeststhe possibility of informal subdivision as notedby Rickards (1976) a possibility reinforced by theseeming restriction of Huttagraptus praematurus tothe lower part of the biozone (Zalasiewicz Williams ampAkhurst 2003)

Biserial graptolites continue to be important Mostof the common normalograptids from the ascensusndashacuminatus Biozone range up into the atavus Biozoneand beyond these include N normalis N angustus Nmedius and N rectangularis

Toghill (1968a) described a vesiculosus Biozoneassemblage from Dobrsquos Linn which equates with thatof the atavus Biozone recorded elsewhere (Rickards1976) Elles amp Wood (1901ndash1918) recorded a zone oflsquoMesograptus modestus and Orthograptus vesiculosusrsquoto account for the assemblage between the acuminatusand cyphus biozones and many of the taxa thatthey recorded clearly indicate an Atavograptus atavusBiozone assemblage

9c Huttagraptus acinaces Biozone

Jonesrsquos (1909) initial description of the Monograptusrheidolensis Biozone assemblage from the Pont Erwyddistrict central Wales was based on the appear-ance of M rheidolensis (= Huttagraptus acinaces)M (= Pribylograptus) sandersoni Dimorphograp-tus confertus swanstoni lsquoClimacograptus hughesirsquo(= Metaclimacograptus slalom) and Glyptograptustamariscus Jonesrsquos (1909) original definition ofthe biozone adequately describes the core acinacesBiozone assemblage Many of the earlier Rhuddaniannormalograptids and dimorphograptids range up intothe biozone (Figs 11 12)

Although Toghill (1968a) recorded H acinaces andG tamariscus sl from his vesiculosus Biozone (=atavus Biozone) both Rickards (1970) and Hutt (1974ndash1975) placed these as key taxa defining the base ofthe acinaces Biozone along with lsquoM hughesirsquo (=M slalom) Rickards (1976) correlated the upper part



of Toghillrsquos vesiculosus Biozone with the acinacesBiozone and suggested an origin for acinaces inthe late atavus Biozone though this has not beensubstantiated by further work (eg Davies et al 1997)

The biozone as a whole is less easy to recognize thanthe atavus Biozone below or the revolutus Biozoneabove Subdivision of this interval is not easy butPribylograptus incommodus Huttagraptus strachaniPristiograptus fragilis pristinus and Pseudorthograptusmutabilis (and questionably Coronograptus gregarius)seem to appear in the upper part of the biozoneIn Central Wales (Zalasiewicz amp Tunnicliff 1994Davies et al 1997) the zone fossil and associatednormalograptids represent the lower part of thebiozone and a more diverse assemblage occurs in theupper part with the incoming of several species in-cluding Metaclimacograptus slalom and Glyptograptustamariscus tamariscus that are commonly recorded atstratigraphically lower levels in other areas

Toghill (1968a) did not recognize an acinacesassemblage in the Birkhill Shale at Dobrsquos Linn theacinaces Biozone appears to be represented by thelower part of his cyphus Biozone (see discussion inHutt 1974ndash1975 Rickards 1976) as well as part of hisunderlying vesiculosus Biozone The acinaces Biozoneand the sub- and superjacent biozones are recognizedin the Birkhill Shales southwest of Dobrsquos Linn to theRhins of Galloway (Stone 1995 McMillan 2002)

9d Monograptus revolutus Biozone

The biozone traditionally placed at this level is that ofCoronograptus cyphus (eg Elles amp Wood 1901ndash1918Rickards 1970 Hutt 1974ndash1975 Rickards 1976)This latter assemblage originally recognized by HLapworth (1900) from the Wye Valley sequence ofRhayader consisted of Coronograptus cyphus cyphusMonograptus revolutus lsquoMonograptusrsquo attenuatusPribylograptus sandersoni Normalograptus rectan-gularis and N normalis

As C c cyphus has been recorded in assemblagesbroadly referable to the underlying acinaces Biozone(eg Zalasiewicz amp Tunnicliff 1994 see also Rickards1976) its appearance cannot define the base of thecyphus Biozone without altering the concept of theoverall assemblage and also attenuating the underlyingacinaces Biozone

M revolutus and C gregarius gregarius appearin the middle of Toghillrsquos (1968a) cyphus Biozoneat Dobrsquos Linn This combined with an increase innumbers of C cyphus cyphus at about the samelevel suggested to Rickards (1976) and Hutt (1974ndash1975) that only the upper part of Toghillrsquos biozonerepresents the cyphus Biozone recognized in otherparts of Britain Elles amp Wood (1901ndash1918) includeda cyphus Biozone in their zonal scheme containing Cc cyphus and C g gregarius Both these forms havebeen recorded from the underlying acinaces Biozone(Rickards 1976 Zalasiewicz amp Tunnicliff 1994)and the appearance of Rhaphidograptus toernquisti

Glyptograptus tamariscus tamariscus Huttagraptusacinaces and Pribylograptus incommodus in theircyphus Biozone suggests that at least the lower partof it is equivalent to the acinaces Biozone

Given this rather complicated state of affairswe consider that the revolutusausterus group ofgraptolites provides a more useful delineation andtheir appearance at the base of the biozone is noted bymost authors (H Lapworth 1900 Jones 1909 Elles ampWood 1901ndash1918 Rickards 1970 1976 Hutt 1974ndash1975 Baker 1981 Zalasiewicz amp Tunnicliff 1994Davies et al 1997) We therefore propose renaming thezone after M revolutus following Bjerreskov (1975)

Other newly appearing species are Coronograptusgregarius gregarius (although this species possibly ori-ginates in the upper acinaces Biozone) Pribylograptusargutus argutus and Metaclimacograptus undulatus(Fig 12) Some taxa continue from the previousbiozone notably Atavograptus atavus Huttagraptusacinaces Normalograptus medius N rectangularisRhaphidograptus toernquisti cf Pseudorthograptusmutabilis Cystograptus vesiculosus and Metaclimaco-graptus slalom but they are mostly in decline and arenot recorded from all areas

A distinct middle to upper part to this biozonecan sometimes be recognized mainly based on theappearance of several glyptograptids such as Gtamariscus distans G t varians G t linearis and Gt angulatus A probable forerunner to the triangulatemonograptids M difformis also appears midwaythrough the biozone

9e Monograptus triangulatus Biozone

The Monograptus triangulatus Biozone represents thelowest part of a broad interval formerly known as theMonograptus gregarius Zone (Lapworth 1878 Ellesamp Wood 1901ndash1918) The gregarius Biozone was stillused in the Britain until the 1960s (Toghill 1968a)Elles amp Wood (1901ndash1918) divided the zone into threesubzones The lowest of these the fimbriatus Subzoneequates with the current triangulatus Biozone Toghill(1968a) described the distribution of graptolites in theBirkhill Shales at Dobrsquos Linn and horizons 33ndash31 ofhis gregarius Biozone contain a typical triangulatuszonal assemblage Sudburyrsquos (1958) detailed work ontriangulate monograptids from the Rheidol Gorge incentral Wales contributed greatly to the concept ofthe existing triangulatus Biozone Despite using thegregarius Biozone herself she also acknowledged apossible three-fold subdivision based on her reassess-ment of the morphologies and ranges of the triangulatemonograptids as a stratigraphically important groupThis enabled Rickards (1976) to outline the distinctiveassemblages comprising the triangulatus magnus andleptotheca biozones

The base of the triangulatus Biozone is markedby the appearance of several triangulate monograptidsincluding Monograptus triangulatus triangulatus Mt separatus and M t predecipiens Other new



appearances include Pristiograptus concinnus Di-versity is high at this stratigraphical level with manytaxa continuing from the previous biozone in additionto the new appearances Some 60 taxa are currentlyrecognized (Figs 12 13)

Locally biostratigraphically barren strata are foundat the base of the biozone For example in the LakeDistrict (Hutt 1974ndash1975) central Wales (Zalasiewiczamp Tunnicliff 1994 Davies et al 1997) and at Llanys-tumdwy North Wales (Baker 1981) taxa suggestingthe middle of the biozone are the first to appear appearabove the cyphus Biozone as recognized by thoseauthors (and in this account referred to the revolutusBiozone)

Subdivision of the triangulatus Biozone is possiblethe middle to upper parts of the biozone are marked bythe incoming of distinctive taxa such as M triangulatusmajor M t fimbriatus Petalolithus minor Rastriteslongispinus Glyptograptus tamariscus acutus Cam-pograptus communis communis and Ca c rostratus

9f Neodiplograptus magnus Biozone

Jones (1909) originally recognized a lsquomagnus bandrsquofrom the Rheidol Gorge section Later studies revealeda magnus Biozone assemblage from the Machynlletharea Wales (Jones amp Pugh 1916) The biozone isdefined by the appearance of Neodiplograptus magnusOther new appearances include Pseudoglyptograp-tus vas (Hutt 1974ndash1975) P barriei Monograptuschrysalis and Neodiplograptus peggyae Monograptustriangulatus fimbriatus (that may be a junior synonymof Monograptus pectinatus Richter Bjerreskov 1975)M t major and M pseudoplanus are commonassociates while M t triangulatus may persist into thelower part of the biozone (Baker 1981) (Fig 13) Thisbiozone has also been recognized in Scotland (Toghill1968a)

Many taxa continue from previous biozones Theupper part of the magnus Biozone is poorly representedin Britain commonly being represented by barren(bioturbated) strata (eg Baker 1981 Davies et al1997)

9g Pribylograptus leptotheca Biozone

Marr amp Nicholson (1888) first identified this biozonein the Skelgill Beds of northern England where itwas named the Monograptus argenteus Zone Elles ampWood (1901ndash1918) termed it the M argenteus Subzoneof the gregarius Zone and recorded the incomingof Pribylograptus leptotheca Monograptus argenteusPristiograptus regularis and P jaculum at this level(although their overall list of species appearancescontains a mixture of forms recorded from both higherand lower levels by other authors) Later Jones amp Pugh(1916) recorded a similar assemblage from the samestratigraphical interval at Machynlleth in Wales andthey referred to it as the leptotheca Biozone this hasbeen more widely adopted as the name for the biozone

Both Monograptus argenteus and Pribylograptusleptotheca have been recorded in Scotland northernEngland and Wales (eg Hutt 1974ndash1975 Baker 1981Davies et al 1997) and although there are variationsin relative abundance the presence of either maycharacterize the base of this biozone (Fig 13) Othernewly appearing taxa recorded include Pristiograptusregularis (see Toghill 1968a) and Pristiograptusjaculum Glyptograptus serratus and Monograptuscerastus Rickards (1976) suggested that Pr leptothecaoriginated in the magnus Biozone although this hasnot been substantiated by further work (eg Davieset al 1997) Hutt (1974ndash1975) and Zalasiewicz (1992b)identified the incoming of the monoclimacid thecalmorphology (eg M imago) at this level in Britain

A major feature of the leptotheca Biozone is themarked increase in monograptids with hooked thecaewhich include Campograptus millepeda and Calobiferus Several species continue from the previousbiozone and Coronograptus gregarius gregarius wassingled out by Hutt (1974ndash1975) as being verycommon

In many regions for example central Wales(Zalasiewicz 1990 Davies et al 1997) leptothecaBiozone assemblages occur in thin fossiliferous levelswithin a generally barren sequence This makessubdivision of this interval difficult in Britain althoughmore continuously fossiliferous sequences are foundoutside Britain (eg Storch 1998)

9h Lituigraptus convolutus Biozone

This biozone was initially described at Skelgill byMarr amp Nicholson (1888) At Dobrsquos Linn this biozonerepresents Lapworthrsquos (1878) original clingani band(lower part of convolutus Biozone) and cometa Zone(upper part of convolutus Biozone)

The broad features of the biozone have beenagreed upon by subsequent authors (Toghill 1968aHutt 1974ndash1975 Rickards 1976 Baker 1981) Anumber of taxa appear at or around the base of thebiozone including L convolutus itself Campograptusclingani Monograptus limatulus Torquigraptus de-cipiens Cephalograptus cometa cometa C tubulari-formis Glyptograptus incertus sl and Torquigraptusurceolinus (which Storch 1998 suggested might be ajunior synonym of M decipiens) (Figs 13 14) Otherdistinctive and useful forms characterizing this biozoneinclude Rastrites spina of Rickards 1970 Para-diversograptus capillaris Monoclimacis crenularisand Rastrites peregrinus Normalograptus scalarisMetaclimacograptus hughesi Pristiograptus jaculumand Campograptus lobiferus have been commonlyreported though they extend beyond the biozone Aprobable first occurrence of Streptograptus has beennoted at this level (Zalasiewicz 1996)

Subdivision of this biozone seems achievableespecially given the faunal diversity at this level butis hampered by the dominance of bioturbated non-graptolitic strata particularly at low stratigraphical



levels in England and Wales Several workers (Toghill1968a Hutt 1974ndash1975 Rickards 1976 Davieset al 1997) record the incoming of Cephalograptuscometa extrema as a reliable indicator of the upperpart of the convolutus Biozone and the usefulnessof the cephalograptid lineage was further emphasizedby Storch (1998) in his thorough review of theconvolutus Biozone in Bohemia Zalasiewicz (1996see also Davies et al 1997) identified a possible lowersubdivision of the convolutus Biozone that contains anarrow form of L convolutus (= Lituigraptus richteriof Storch 1998) At least part of this division mightnow however be considered to represent the upperpart of the leptotheca Biozone (cf Storch 1998)

9i Stimulograptus sedgwickii Biozone

This biozonal assemblage was originally identifiedfrom the upper Birkhill Shale Formation of Dobrsquos Linnby Lapworth (1878) and he named it the M spinigerusBiozone (it is now named after the senior synonymSt sedgwickii) He recorded a diverse fauna anddistinguished an upper and lower subdivision withinthe biozone

The base is defined by the appearance of Stim-ulograptus sedgwickii which appears together withNeolagarograptus tenuis (Hutt 1974ndash1975) Sugges-tions of a slightly earlier origin for St sedgwickii(Rickards 1976) have not been substantiated by furtherwork (Davies et al 1997) Other incoming taxainclude Glyptograptus sinuatus crateriformis Pribylo-graptus argutus sequens Glyptograptus packhami andParapetalolithus kurcki (Rickards 1970 1976 Hutt1974ndash1975) together with Torquigraptus linterni andquestionably Rastrites gracilis (Williams et al 2003b)Hutt (1974ndash1975) also referred to the characteristicabundance of Glyptograptus incertus at the base ofthe biozone (see Loydell 1992ndash1993a for discussion)while Oktavites contortus Streptograptus ansulosusTorquigraptus involutus and Metaclimacograptus un-dulatus are common in though not confined to thisbiozone (Fig 14)

L tenuis seems to be restricted to the lower partof the biozone (Rickards 1976 Davies et al 1997)and thus appears to form a useful basis for subdivision(cf Storch 2001 Storch amp Massa 2006 Melchin2007) At Dobrsquos Linn this species shows markedstratigraphical variations in abundance within its range(Pannell Clarkson amp Zalasiewicz 2006)

9j Stimulograptus halli Biozone

Jones amp Pugh (1916) first recognized the Stimulograp-tus halli Biozone in the MachynllethndashLlyfnant areaof central Wales as an upper part of the sedgwickiiBiozone Rickards (1976) considered that the halli andsedgwickii Biozone assemblages were not sufficientlydistinctive to be separately recognizable and owing todifficulties in distinguishing between Stimulograptussedgwickii and S halli recommended that the halli

Biozone be removed from the UK biostratigraphicalscheme Subsequently however Loydell (1991a) wasable to differentiate halli Biozone assemblages inthe Cwmsymlog Formation of western mid-Walesand reinstated the biozone Loydell (1992ndash1993a)recorded that species defining the base of the biozoneare Stimulograptus halli Pristiograptus pristinus andRastrites linnaei (Fig 14) Other incoming speciesare Rastrites schaueri Paradiversograptus capillarissensu Loydell lsquoMonograptusrsquo admirabilis and Para-petalolithus praecedens A number of relatively long-ranging species also occur including lsquoMonograp-tusrsquo capis Torquigraptus involutus Stimulograptussedgwickii and Oktavites contortus Loydell (1991b)recognized a halli Biozone assemblage similar to thatfound in Wales in the upper Birkhill Shales in DobrsquosLinn southern Scotland

9k Spirograptus guerichi Biozone

This biozone was formerly a part of the turriculatusBiozone as recorded by Elles amp Wood (1901ndash1918)and others Formerly the lower part of the turriculatusBiozone was separated off as the Rastrites maximusSubzone this subzone was first postulated at DobrsquosLinn (Lapworth 1878) but Loydell (1991b) found thatR maximus does not appear to occur there and theUpper Birkhill Shales at Dobrsquos Linn are now assignedto the halli Biozone (see above) Rickards (1976)remarked that the maximus Subzone did not occur at thetype locality of the turriculatus Biozone at Browgill inthe English Lake District (Marr amp Nicholson 1888)but he (Rickards 1970 1976) identified the maximusSubzone in the Howgill Fells and considered it to be animportant part of the turriculatus Biozone although thesubzone itself was defined only on the presence of Rmaximus itself Toghill (1968a) described a maximusSubzone assemblage from the upper Birkhill Shalesand Hutt (1974ndash1975) recorded one locality containingR maximus in the Lake District

Loydell (1991ab) did not use the maximus Subzonefor the Anglo-Welsh sequence (although he did recordthe species) and he divided the turriculatus Biozoneinto six subzones based on his work in western mid-Wales (Fig 2) This biostratigraphical subdivisionwas enhanced when the former turriculatus Biozonewas divided into two creating a lower Spirograptusguerichi Biozone followed by an upper Spirograptusturriculatus Biozone (Loydell 1992ndash1993a LoydellStorch amp Melchin 1993) His six subzones remainedin place with the guerichindashturriculatus biozonalboundary occurring in the middle of the utilis SubzoneLoydell Storch amp Melchin (1993) having observedthat Spirograptus turriculatus itself does not appearuntil the middle of the turriculatus Biozone as formerlyunderstood defined the guerichi Biozone as lsquothe inter-val from the first appearance of Spirograptus guerichi tothat of Spirograptus turriculatusrsquo Davies et al (1997)employed the new biozones and their subdivisions inthe LlanilarndashRhayader district but noted that not all of



Loydellrsquos subzones could be consistently recognizedMcMillan (2002) likewise adopted subdivision into theguerichi and turriculatus biozones Loydellrsquos (1992ndash1993a) guerichi and turriculatus biozones and theircomponent subzones are defined by the appearance orrelative abundance of their index species

9k1 Paradiversograptus runcinatus Subzone

The base is delineated by the appearance of Para-diversograptus runcinatus and Spirograptus guerichiwith the eponym being abundant (Loydell 1991a1992ndash1993a) The numbers of P runcinatus have beenenhanced by current sorting but this does not reducethe usefulness of the subzone as it can be recognizedin Scandinavia (Loydell 1992ndash1993a) Davies et al(1997) did not recognize the subzone in the LlanilarndashRhayader district and assigned some localities to a run-cinatus to renaudi interval lsquoMonograptusrsquo gemmatusPristiograptus renaudi Streptograptus plumosus andStr pseudoruncinatus appear in this subzone (Fig 15)

9k2 lsquoMonograptusrsquo gemmatus Subzone

Loydell (1991a 1992ndash1993a) described a diversedistinctive assemblage including Streptograptus pseu-doruncinatus Spirograptus guerichi Rastrites fugaxGlyptograptus fastigatus G tamariscus tamariscusand lsquoMonograptusrsquo gemmatus In addition to theseseveral species appear at the base of the subzone andare confined to it for example the parapetalolithidsParapetalolithus elongatus P globosus and P regiuswith Glyptograptus auritus (Fig 15) This subzone hasbeen recognized by Davies et al (1997)

9k3 Pristiograptus renaudi Subzone

This subzone is characterized by abundant Pristio-graptus renaudi and Streptograptus strachani (Loydell1991a 1992ndash1993a) although neither of these taxaoriginate at the base of this subzone However Loydellrecorded that Torquigraptus planus and T caveifirst appear here and they are useful indicators ofthe renaudi to utilis subzone interval Other newlyappearing species include Monograptus marri andParapetalolithus hispanicus (Fig 15) Both Loydell(1991a) and Davies et al (1997) noted that thetransition from the gemmatus Subzone into thissubzone has not yet been recognized in a continuoussection and only one faunal assemblage from theLlanilarndashRhayader district has been assigned to thisinterval (Davies et al 1997)

9l Spirograptus turriculatus Biozone

In its current more biostratigraphically restrictedusage the turriculatus Biozone is defined as lyingbetween lsquothe first appearance of Spirograptus turricu-latus to that of lsquoMonograptusrsquo crispus or other speciesindicative of the crispus Biozonersquo (Loydell 1992ndash

1993a) Spirograptus turriculatus is taxonomicallydistinct from Spirograptus guerichi (Loydell Storchamp Melchin 1993) which characterizes the underlyingbiozone As a result older definitions for the base ofthe turriculatus biozone (Rickards 1970 1976 Hutt1974ndash1975) are no longer applicable since these nowrefer to the base of the guerichi Biozone Loydellrsquos(1992ndash1993a) definition of the base of the turriculatusBiozone placed it in the middle of the Stimulograptusutilis Subzone (Fig 2) One means of avoiding thesituation of placing a zonal boundary within a subzonemight be to place the base of the turriculatus Biozoneat the base of a slightly extended johnsonae Biozone tobe defined by the first appearance rather than acme ofjohnsonae which coincides with the first appearance ofSp turriculatus (M Melchin pers comm) the currentdefinition of the johnsonae Subzone however has beenfound to work well in practice (eg Davies et al 1997)

9l1 Stimulograptus utilis Subzone

Loydell (1991a) erected this subzone as the fourth sub-division of the old turriculatus Biozone SubsequentlyLoydell (1992ndash1993a) divided the utilis Subzoneinto two parts marking the boundary between theguerichi and turriculatus biozones This was based onthe incoming of Parapetalolithus tenuis Spirograptusturriculatus and Streptograptus johnsonae and anabundance of Monograptus marri and Streptograptusplumosus in the middle of the subzone (Fig 15)Several species seem to disappear mid-subzone includ-ing Parapetalolithus kurcki Rastrites linnaei Paradi-versograptus runcinatus Parapetalolithus conicus (=Pa hispanicus) and Pseudostreptograptus williamsiDavies et al (1997) recorded the utilis Subzone widelyin the LlanilarndashRhayader district

9l2 Streptograptus johnsonae Subzone

This subzone is defined on the abundance of Strep-tograptus johnsonae and common Monograptus bjer-reskovae and M marri (Loydell 1991a 1992ndash1993a)and has been recognized in the LlanilarndashRhayaderarea (Davies et al 1997) Appearances at the base ofthe subzone are rare including only Parapetalolithusschaueri and Pristiograptus schucherti (Loydell 1992ndash1993a) As the range charts demonstrate (Fig 15) asignificant proportion of the low-diversity johnsonaeSubzone assemblage is composed of relatively long-ranging species

9l3 Torquigraptus proteus Subzone

Torquigraptus proteus appears at the base of thissubzone and its presence and abundance characterizesthis interval (Loydell 1991a 1992ndash1993a) As otherauthors record (Zalasiewicz 1994 Davies et al1997) appearances also include Monograptus rickardsi(which may be a junior synonym of M priodonLoydell 1992ndash1993a) and Monoclimacis galaensis



as well as Pristiograptus huttae (see Loydell 1992ndash1993a) and Streptograptus pseudobecki (Zalasiewicz1994 Loydell 1990) The bulk of this relatively smallassemblage (Figs 15 16) contains taxa from underlyingbiozones and subzones

9l4 Torquigraptus carnicus Subzone

Zalasiewicz (1994) and Davies et al (1997) recognizeda further subzone in central Wales representing thehighest part of the turriculatus Biozone The base ofthis subzone is characterized by the appearance of Tcarnicus while Streptograptus whitei S exiguus andpossibly Stimulograptus clintonensis also appear in thisinterval as does Monograptus aff crispus a narrowprecursor to the eponym of the succeeding biozone(Fig 16) Streptograptus storchi is noted as abundantin the carnicus Subzone (Zalasiewicz 1994 Davieset al 1997)

9m lsquoMonograptusrsquo crispus Biozone

Initially described from the Lake District (Marramp Nicholson 1888) this biozone is defined bythe incoming of lsquoMonograptusrsquo crispus (assigned toStreptograptus by Loydell amp Maletz 2004) while thedistinctive and useful Cochlograptus veles (= M discusof some authors) appears at about the same level (Fig16) In central Wales the boundary between the crispusBiozone and the underlying turriculatus Biozone wasnot easily resolved (Zalasiewicz 1994 Davies et al1997) as both these characteristic species are rareat the base of the biozone Loydell (1991a 1992ndash1993a) noted also the incoming of Streptograptus spnov of Howe (M P A Howe unpub PhD thesisUniv Cambridge 1982) at or near the base of thebiozone Zalasiewicz (1994 see also Davies et al 1997)divided the crispus Biozone into three subzones basedon sections in central Wales As S crispus does notrange into the highest of these either in Britain orelsewhere the sartorius Subzone is here elevated tobiozonal status

9m1 Monoclimacis galaensis Subzone

Zalasiewicz (1994) and Davies et al (1997) re-cognized this interval as a partial-range subzonecharacterized by the overlap of Monoclimacisgalaensis and Torquigraptus carnicus with lsquoMonograp-tusrsquo crispus and Cochlograptus veles (= Monograptusdiscus) Stimulograptus clintonensis and Streptograp-tus exiguus are also common at this level (Fig 16)

9m2 Streptograptus loydelli Subzone

Zalasiewicz (1994) described this subzone as a partial-range subzone defined by the overlap of lsquoMonograptusrsquocrispus and Streptograptus loydelli He termed itthe lsquoMonograptusrsquo crispus Subzone the name being

changed here to reflect the taxon whose incomingdefines its base lsquoMonograptusrsquo crispus is abundantin this subzone disappearing at its top (Fig 16) Thissubzone is well exposed in the Cwm Ystwyth sectionin central Wales (Davies et al 1997)

9n Streptograptus sartorius Biozone

The base of this biozone is represented by the incomingof Streptograptus sartorius together with Torquigrap-tus pragensis pragensis and Torquigraptus pragensisruzickai and the disappearance of lsquoMonograptusrsquocrispus (Zalasiewicz 1994) (Fig 16) Davies et al(1997) also recorded this biozone at Cwm Ystwythand described the interval as akin to an interregnumwith low faunal diversity

9o Monoclimacis griestoniensis Biozone

First recognized by Wood (1906) in the Talerddig Gritsof Trannon Wales this biozone has an assemblagecharacterized by an incoming of monoclimacids Itsbase is defined by the incoming of the zone fossilMonoclimacis griestoniensis It has been more usuallyrecognized in central Wales by the incoming of Mono-climacis directa (= Monograptus cf griestoniensis ofElles amp Wood see Zalasiewicz Loydell amp Storch1995) which there seemed to appear at about the samelevel (Zalasiewicz 1994 Davies et al 1997) Wilsonrsquos(D R Wilson unpub PhD thesis Univ Birmingham1954) work suggests that it might appear at a slightlylower level in the Howgill Fells

In central Wales the griestoniensis Biozone can beinformally subdivided A lower interval is character-ized by abundant Monoclimacis directa co-occurringwith Monograptus pseudocommunis Streptograptusaff loydelli of Zalasiewicz 1994 and Torquigraptuspergracilis of Zalasiewicz 1994 (Fig 16) Monocli-macis griestoniensis ss dominates the upper part ofthe biozone (Zalasiewicz 1990 1994) Monograptuspriodon C veles (= M discus) and Pristiograptusnudus range through the biozone

9p Monoclimacis crenulata Biozone

Initially referred to as the Monograptus crenulatusBiozone by Wood (1906) in the Trannon area thebiozone was originally defined on the appearance ofthe zone fossil (= Monoclimacis crenulata) associatedwith an undistinctive assemblage generally of lowdiversity More recent work in central Wales hassuggested that the incoming of Monoclimacis vomerinamay be a more useful indicator of the base of thisbiozone (Zalasiewicz 1994 Davies et al 1997) Theassemblage includes taxa from underlying biozonesincluding C veles (= M discus) and M priodon (Fig16) The Monoclimacis crenulata Biozone formerlyincluded all British strata from the top of theMonoclimacis griestoniensis Biozone to the base of



the Wenlock Series Rickards (1976) noted that thisbiozone was rarely found abroad where a more refinedbiostratigraphical subdivision could be recognized(Boucek 1953 Bjerreskov 1975) Since then work byLoydell amp Cave (1993 1996) has led to the recognitionof more biozones within the upper Telychian of Walesand the current crenulata Biozone now represents onlythe lowest part the original biozone

9q Oktavites spiralis Biozone

Graptolite assemblages representing the Oktavitesspiralis Biozone were recognized relatively recentlyin the UK by Loydell amp Cave (1993 1996) Initialbiostratigraphical work at Buttington Brick Pit cent-ral Wales (Loydell amp Cave 1993) and subsequentstudies in eastern mid-Wales (Loydell amp Cave 1996)resulted in division of the long-established crenulataBiozone and allowed direct comparison with thegraptolite biozonation of Bohemia (Boucek 1953) andScandinavia (Bjerreskov 1975) The Oktavites spiralisBiozone has a distinctive faunal assemblage andLoydell amp Cave (1993 1996) recorded the introductionof several taxa through the biozone These include thezone fossil (previously commonly given a longer rangein the UK (eg Rickards 1976) prior to closer scrutinyof the Telychian spiraliform monograptids many ofwhich are superficially similar) and Monoclimacishemmanni Streptograptus anguinus Monoclimacisgeinitzi Streptograptus nodifer (referred to Awaro-graptus by Zalasiewicz amp Howe 2003) Barrandeo-graptus bornholmensis and Stimulograptus vesiculosus(Figs 16 17)

9r Cyrtograptus lapworthi Biozone

The Cyrtograptus lapworthi Biozone was first recordedin Britain by Loydell amp Cave (1996) from the BanwyRiver section central Wales It equates roughly withthe upper part of the spiralis Biozone and the Sto-matograptus grandis Biozone of the Czech RepublicLoydell amp Cave (1996) described a relatively diverseand characteristic graptolite assemblage Several newspecies appear at the base of the biozone includingthe zone fossil (Fig 17) Some are confined to itslower and middle parts suggesting a potential for sub-division these include Monoclimacis sublinnarssoniStreptograptus speciosus Streptograptus wimani andPristiograptus largus A number of taxa continue fromthe previous biozone and a few appear in the middleof the biozone notably Monoclimacis basilica andBarrandeograptus pulchellus C lapworthi itself marksthe first appearance of Cyrtograptus in Britain In theLlanilarndashRhayader district of central Wales Davieset al (1997) assigned strata overlying the spiralisBiozone to a lsquospiraliscentrifugus interregnumrsquo the as-semblage being dominated by long-ranging graptolitessuch as the members of the Monoclimacis vomerina

and Monograptus priodon groups and Retiolites gein-itzianus

9s Cyrtograptus insectus Biozone

The biostratigraphical succession outlined by Loydellamp Cave (1996) in the Banwy River section includedthe first record of the Cyrtograptus insectus Biozonein Britain The biozone contains a number of taxawhose ranges are limited to the lowerndashmiddle ormiddlendashupper parts of this interval indicating thepossibility of further biostratigraphical subdivision(Fig 17) This biozone is notable for the introductionof Mediograptus Mediograptus flittoni appears atthe base together with Monoclimacis shottoni Cinsectus and Cyrtograptus sp of Loydell amp CaveMonoclimacis linnarssoni disappears in the lower partof the biozone Species defining the middle and upperparts of the biozone in the Banwy section includeMonograptus pseudocultellus Mediograptus morleyaeand Mediograptus sp aff inconspicuus of Loydell ampCave

9t Cyrtograptus centrifugus Biozone

The Cyrtograptus centrifugus Biozone was first identi-fied in Britain in the Howgill Fells northern England(Rickards 1967) Rickards (1967 1976) described anassemblage containing C centrifugus monoclimacidsand monograptids The base of this biozone has longbeen equated with the base of the Wenlock Seriesin the UK although more recent micropalaeonto-logical evaluation at Hughley Brook suggests thatthis level actually equates to a horizon within theupper centrifugus or succeeding murchisoni graptoliteBiozone (Mullins amp Aldridge 2004) The incomingof the zone fossil defines the biozonal base althoughseveral other species also appear for the first time(Rickards 1976 Loydell amp Cave 1996 Davies et al1997 Zalasiewicz amp Williams 1999) These includeMediograptus danbyi Med cautleyensis Monograptussimulatus and Monoclimacis sp 1 (sensu Zalasiewiczamp Williams 1999) (Fig 17) Mediograptus inconspi-cuus and questionably Mediograptus flexuosus appearin the middle to upper part of the biozone These areaccompanied by relatively long-lived taxa ranging fromprevious zones (Loydell amp Cave 1996 Zalasiewicz ampWilliams 1999 Davies et al 1997)

9u Cyrtograptus murchisoni Biozone

In many areas of Britain the murchisoni Biozoneassemblage is often indistinguishable from the un-derlying centrifugus Biozone where the eponym isabsent (Rickards 1967 1976 Zalasiewicz amp Williams1999 Davies et al 1997) The biozone was initiallyrecognized by Lapworth (1879ndash1880) from BuilthWells and contains the index species together withMonograptus priodon and Monoclimacis vomerina In



central Wales Loydell amp Cave (1996) and Zalasiewiczamp Williams (1999) have recognized taxa such asMonoclimacis vikensis Mcl adunca Pristiograptuspraedubius Monograptus radotinensis radotinensisCyrtograptus bohemicus and Pseudoplegmatograptuswenlockianus (Fig 17) Loydell amp Cave (1996) notedthat species diversity drops markedly in the upperpart of the biozone indicating a potential for futuresubdivision

9v Monograptus firmus Biozone

The rapid decline in diversity in the upper part ofthe murchisoni Biozone coupled with the incomingof M firmus in the Banwy River section centralWales resulted in Loydell amp Cave (1996) establishingthe firmus Biozone in Britain for the first timeApproximately seven species most of which havelong biostratigraphical ranges are found at this levelthese include Monograptus priodon Monoclimacisvomerina and possibly M basilica (Fig 17) Loydell ampCave (1996) identified the long-ranging Pristiograptusdubius as appearing in the biozone Zalasiewicz ampWilliams (1999) reported the appearance of M firmussl from strata which they assigned to the upper part ofthe murchisoni Biozone at Builth Wells in Wales butthey did not recognize a discrete firmus Biozone

9w Monograptus riccartonensis Biozone

The riccartonensis Biozone was first recognized inthe UK by Elles (1900) at Builth Wells south-centralWales It has since been recognized in many areasof Britain and notable studies include Rickardsrsquos(1967 1969) work in northern England that of Davieset al (1997) in the LlanilarndashRhayader district ofcentral Wales and Zalasiewicz amp Williamsrsquos (1999) re-examination of the sequence at Builth Wells The baseof the biozone is generally taken at the incoming ofMonograptus riccartonensis the stratigraphical rangeof which defines the biozone (Fig 17) this taxondominates most assemblages

Several authors have noted stratigraphical variationsin specific composition and diversity in this generallyimpoverished interval and this might form the basis offuture two- or three-fold subdivision (Rickards 19671976 White et al 1992 Zalasiewicz amp Williams1999) The middle to upper parts of this biozoneare generally more diverse and include Pristiograptusdubius sl Monograptus firmus sl M radotinensisinclinatus and the first appearance of Monograptusantennularius and possibly of Monoclimacis flumen-dosae

9x Note on middle Wenlock graptolite biostratigraphy

The interval from the upper part of the riccartonensisBiozone through to the lundgreni Biozone is problem-atical in the British Isles and a number of biozonal

schemes have been proposed This account (Fig 2)uses the most recent of these (Zalasiewicz amp Williams1999) which is based upon a re-examination of thehistorically important (Elles 1900 Jones 1947) Builthdistrict of south-central Wales The problems andsuggested correlations with earlier schemes and thoseused elsewhere in the world are outlined in that paperThe most important difference from widely used earlierbiozonations (eg Rickards 1976) is that separateflexilis and ellesae biozones are not recognized becauseMonograptus flexilis appears earlier than and thenlargely co-exists with Cyrtograptus rigidus at Builthwhile C ellesae appears later than C lundgreni (Za-lasiewicz amp Williams 1999 Williams amp Zalasiewicz2004) The biostratigraphical problems in part reflectimperfect taxonomy and in part originate from andcontinue to be exacerbated by biofacies control MostUK middle Wenlock sequences (including Builth) aredominated by a few morphologically variable and long-ranging monograptid monoclimacid and pristiograptidtaxa while the biostratigraphically useful cyrtograptidsare rare in comparison to successions such as those ofBohemia (eg Storch 1994)

9y Pristiograptus dubius Biozone

The dubius Biozone was originally defined in theCzech Republic (Boucek 1960 also Storch 1994)and Zalasiewicz amp Williams (1999) recognized thebiozone in the UK for the first time at Builth WellsThis interval is an interregnum with recognitionlargely reliant on identification of the biozones directlyabove and below The biozone is typified by variablelong-lived taxa of the Pristiograptus dubius groupas well as by Monograptus priodonflemingii andMonoclimacis flumendosae (Figs 17 18) Rare firstoccurrences recorded at Builth include Mediograptusex gr retroflexus and M flexilis the latter first beingfound midway up the biozone The dubius Biozone isapproximately equivalent to the antennularius Biozoneof Rickards (1965 1967 1969) and White et al(1992)

9z Cyrtograptus rigidus Biozone

The rigidus Biozone was originally defined at Builthby Elles (1900) as her symmetricus Zone Her speciesC symmetricus was however a misidentification of Crigidus and the name of the biozone was subsequentlychanged The base of the rigidus Biozone is defined bythe appearance of the index fossil which is limited tothe biozone The rigidus Biozone as defined hereinextends to the base of the lundgreni Biozone andtherefore equates with Ellesrsquos (1900) linnarssoni Zone(= flexilis Biozone Rickards 1976) as well as hersymmetricus (= rigidus) Zone (see Zalasiewicz ampWilliams 1999)

Other elements of the assemblage include taxaranging up from the dubius Biozone such as



Monograptus flexilis M priodonflemingii Medio-graptus ex gr retroflexus Monoclimacis flumend-osae and graptolites of the Pristiograptus dubiusgroup including the distinctively broad P pseudolatus(Fig 18)

At Builth (Zalasiewicz amp Williams 1999) this unitcould not be subdivided because (1) Monograptusflexilis one index species of the formerly recognizedflexilislinnarssoni Biozone in fact appears below Crigidus and then has a range largely that overlapswith it (2) the other index species Cyrtograptuslinnarssoni seems to be based on an unusually narrowandor deformed example of C rigidus sl thistaxon has accordingly been widely misidentified mostattributed specimens being referable to C rigidusand (3) temporal subspecies of C rigidus could notbe distinguished at Builth C rigidus cautleyensisRickards 1967 has been interpreted as a late slendersubspecies indicative of the flexilislinnarssoni Biozone(eg Rickards 1976) The type material of this taxonfrom the Howgill Fells does seem to be a recognizableslender morphotype (Williams amp Zalasiewicz 2004)but it could not be recognized as distinct at Builthon present evidence it may be a true geographicalsubspecies restricted to northern England Finally theremainder of the assemblage consisting of abundantpristiograptid monograptid and monoclimacid grap-tolites that belong to a few variable long-ranging taxaare of limited biostratigraphical use

9aa Cyrtograptus lundgreni Biozone

This biozone was first defined at Builth by Elles (1900)The base of the biozone is recognized by the incomingof the index species However re-examination of theBuilth succession (Zalasiewicz amp Williams 1999) hasshown that it overlies the rigidus Biozone directlywithout the intervening linnarssoni or ellesae biozonesthat Elles had recognized Zalasiewicz amp Williams(1999 see also Williams amp Zalasiewicz 2004) foundthat C ellesae the zonal index species of the ellesaeBiozone in fact appears higher than C lundgreniand the ranges of C ellesae and C lundgreni overlap(see also Warren 1971 Rickards 1976) thus we donot recognize the ellesae Biozone in this accountThis causes problems regarding the links betweenbiostratigraphy and chronostratigraphy because theboundary between the Sheinwoodian and Homerianstages was placed at the base of the ellesae Biozoneas recognized in the Welsh Borders (Bassett Rickardsamp Warren 1975 see discussion in Zalasiewicz ampWilliams 1999 and Melchin Cooper amp Sadler 2004)

There is some potential for finer subdivision Atthe base of the biozone C lundgreni was found tooverlap with the latest occurrences of Mediograptus exgr retroflexus There might be also a discrete middleto upper biozonal assemblage including Cyrtograptusramosus C hamatus C ellesae and Testograptustestis although its recognition may be hampered in

practice because such taxa are rare in comparison withthe more long-ranging pristiograptids monoclimacidsand monograptids (Fig 18) Davies et al (1997)and Bassett Rickards amp Warren (1975) recorded thisbiozone from central Wales and Warren et al (1984)used it in north Wales

9bb Gothograptus nassa Biozone

The nassa Biozone was first adopted for use in Britainby Warren (1971) working in north Wales It succeedsa major graptolite extinction event with most of thegraptolites characteristic of the preceding lundgreniBiozone not surviving into this interval (Rickards1976 Jaeger 1991) Indeed only four taxa have beenrecorded (Fig 18) one of which is a first appearanceThe assemblage consists of Pristiograptus dubius (andits subspecies ludlowiensis) and Gothograptus nassawhich dominate most assemblages with P aff jaegeriof Holland Rickards amp Warren 1969 reliable recordsof Pristiograptus jaegeri appear in the upper partof the biozone G nassa has been reported beyondits biozone in Britain (Fig 18) although subsequentdetailed work in Arctic Canada Baltica and theCzech Republic (Porebska Kozłowska-Dawidziuk ampMasiak 2004) suggests that it is confined there to itsbiozone and the overlying praedeubeli Biozone (notrecognized in Britain) of that region this suggeststhat careful reassessment of UK material of nassais needed Zalasiewicz amp Williams (1999) referredonly to a nassandashludensis Biozone representing theuppermost interval of Wenlock strata at Builth Wellsboth indicator species are rare in this area and theirbiostratigraphical ranges cannot be clearly constrainedIn general the low abundance and diversity ofgraptolites in upper Wenlock strata in the British Islesmake it difficult to apply the fine upper Wenlockgraptolite biostratigraphy recognized elsewhere in theworld (eg Lenz et al 2006)

9cc Monograptus ludensis Biozone

Originally recognized as the vulgaris Zone by Wood(1900) at Builth and Long Mountain this biozone wasredefined and renamed by Holland Rickards amp Warren(1969 see also Rickards 1976)

The base of the ludensis Biozone is taken at theincoming of the biozonal species (Fig 18) which inthe lower part of the interval co-occurs with taxafrom the preceding G nassa Biozone This biozonalassemblage indicates the possibility of a more refinedbiostratigraphic subdivision (see Rickards 1976) asthe first occurrences of other species range from themiddle to upper part of the biozone These includeHoloretiolites (Balticograptus) lawsoni Pristiograptusauctus Monograptus deubeli and M aff uncinatusorbatus The loss of P aff jaegeri of HollandRickards amp Warren (1969) midway through the biozone



reinforces the distinction between a lower and an upperassemblage within the ludensis Biozone

9dd Neodiversograptus nilssoni Biozone

In recent years much biostratigraphical work has beenundertaken on British strata of Ludlow age by theBritish Geological Survey on Ludlow successions incentral Wales (Schofield et al 2004 Barclay et al2005) Nevertheless the biozonal criteria for the serieshave not changed significantly since Rickardsrsquos (1976)review of Silurian graptolite biostratigraphy The baseof the N nilssoni Biozone coincides only approximately(Melchin Cooper amp Sadler 2004) with the base of theLudlow Series Many Lower Ludlow taxa had beenidentified in Britain notably from the Lake Districtand Ludlow itself (Nicholson 1868 Hopkinson 1873)before Lapworth (1879ndash1880) working in centralWales and the Welsh Borderlands designated the lsquozoneof Monograptus nilssonirsquo which included the wholeLower Ludlow Further studies most importantly thoseof Wood (1900) led to refinement and subdivisionof this broad biostratigraphical unit (Rickards 19671969 Warren 1971)

The nilssoni Biozone shows a much greater specificdiversity than the preceding Wenlock biozones with theappearance and diversification of Saetograptus beingespecially characteristic The appearance of the zonefossil defines its base and taxa such as Monograptusuncinatus orbatus Plectograptus macilentus Spino-graptus spinosus Saetograptus colonus colonus Svarians varians and Bohemograptus bohemicus sl alsoappear at about this level (Fig 18)

In north Wales Warren (in Warren et al 1984p 54) divided the nilssoni Biozone into lower and upperdivisions and there is potential for further subdivision(see discussion in Rickards 1976) There is a distinctlower to middle zonal assemblage with M ludensisand P auctus which disappears in the mid-nilssoniBiozone A distinct assemblage appears in the middleto upper part of the biozone and contains many newgenera and species of Monograptidae notably Cucul-lograptus (Lobograptus) progenitor C (L) scanicusC (L) simplex Monoclimacis micropoma Mcl hauptiPristiograptus vicinus and Crinitograptus crinitus Thesaetograptids diversify rapidly in this upper intervalwith the incoming of Saetograptus roemeri S fritschifritschi S leintwardinensis incipiens S wandalensisS chimaera chimaera S chimaera salweyi and S chi-maera semispinosus This biostratigraphical refinementhas been expressed in Poland and the Czech Republicin terms of a lower nilssoni Biozone succeeded byan upper progenitor Biozone (Urbanek 1966 Teller1969 Pribyl 1983) Melchin Cooper amp Sadler (2004)and Korenrsquo et al (1996) indeed used this assemblage(and the incoming of C (L) scanicus) to define thebase of the scanicus Biozone and this resolutionmight ultimately prove optimal also for the Britishsuccession

9ee Cucullograptus (Lobograptus) scanicus Biozone

Wood (1900) established the scanicus Biozone in theBuilth and Ludlow areas and while widely employedthis interval remains problematical in the British IslesRickardsrsquos (1976) range chart showed no appearancesat the base of this interval and it was characterizedby extinctions of many nilssoni Biozone taxa andan increase in the abundance of Cucullograptus(Lobograptus) scanicus and Saetograptus chimaerachimaera (Wood 1900 Rickards 1976) (Figs 18 19)Recent work in the Montgomery district of centralWales (White in Cave amp Hains 2001 p 69) showeda number of appearances there at this level includingmost of the subspecies of S chimaera The incomingof Pristiograptus tumescens tumescens Saetograptusclunensis Pristiograptus welchae and Bohemograptusbohemicus tenuis was shown in the middle part of thescanicus interval by Rickards (1976)

9ff Saetograptus incipiens or Pristiograptus tumescensBiozone

Wood (1900) established this biozone in Wales and theWelsh Borderland and employed both zonal terms Aswith the preceding scanicus Biozone it is somewhatill-defined and approximates to an interregnum Thebiozonal name varies locally according to the relativeabundance andor the presence or absence of Saeto-graptus incipiens and Pristiograptus tumescens bothof which originate in earlier biozones (see discussion inRickards 1976) Graptolite species diversity is reducedin the incipienstumescens Biozone compared withprevious Ludlow biozones with approximately tenconfirmed taxa (Figs 18 19) most of them rangingfrom the preceding biozones Only one new formappears Saetograptus aff incipiens (Wood 1900) Anumber of species have been recorded as disappearingin the lower to middle part of the interval (Rickards1976) perhaps indicating the possibility of subdivisionthese include Monoclimacis haupti Pristiograptusvicinus Saetograptus clunensis and S varians variansIn practice though this interval sharing so manytaxa with the scanicus Biozone is hard to recognizeparticularly in spot localities

9gg Saetograptus leintwardinensis leintwardinensisBiozone

This biozone was initially defined by Marr (1892) inthe Lake District and has been widely recognized inthe UK (Wood 1900 Holland Lawson amp Walmsley1963 Rickards 1967) largely on the incoming of Sl leintwardinensis (Fig 19) Only two other taxa areconfirmed in this biozone namely Saetograptus affincipiens which continues from the previous biozoneand Saetograptus leintwardinensis primus which isconfined to the lowerndashmiddle part of the biozone(Shergold amp Shirley 1968) Such a low-diversity



Table 1 Ordovician range chart sources (England amp Wales)(for Figs 3ndash7)

Source number Reference

1 Baker 19812 Beckly amp Maletz 19913 Beckly 19884 Rickards 20025 Davies et al 19976 Bulman 19637 Cooper et al 20048 Gibbons amp McCarroll 19939 Rushton amp Zalasiewicz 1999

10 Cooper et al 199511 Davies 192912 Elles 193313 Elles 194014 Elles amp Wood 1901ndash191815 Fortey amp Owens 198716 Fortey Beckly amp Rushton 199017 Hughes 198918 Hutt amp Rickards 197019 Jenkins 198220 Jenkins 198321 Maletz Rushton amp Lindholm 199122 Molyneux amp Rushton 198823 Rickards 197024 Rushton amp Molyneux 198925 Skevington 196626 Skevington 197027 Skevington 197328 Strachan 198629 Strahan et al 191430 Toghill 1968a31 Toghill 1970a32 Wadge Nutt amp Skevington 197233 Zalasiewicz 198634 Zalasiewicz 1992a35 Zalasiewicz amp Tunnicliff 199436 Zalasiewicz Rushton amp Owen 199537 Young Gibbons amp McCarroll 200238 Williams et al 2003a39 Skevington amp Jackson 197640 Cocks et al 198441 Legrand in Rushton 198242 Stubblefield amp Bulman 192743 Howells amp Smith 199744 Pratt Woodhall amp Howells 199545 Bulman amp Rushton 197346 Old Sumbler amp Ambrose 198747 Owens et al 198248 Rushton 200649 Rickards 2004

assemblage may reflect a deteriorating environmentor a deepening evolutionary crisis amongst Britishgraptolites at this time

9hh Bohemograptus proliferation Biozone

This biozone was originally described in the UKby Holland amp Palmer (1974) when they identifiedBohemograptus bohemicus tenuis from strata overlyingthe leintwardinensis Biozone in the Welsh Borderlands(see also White in Cave amp Hains 2001) This taxonis the youngest graptolite in the UK biostratigraphicalsequence and the sole representative in this biozone(Fig 19) B bohemicus tenuis has not been reportedfrom the immediately underlying leintwardinensisBiozone despite its origination earlier in the Ludlowin the scanicus Biozone (Rickards 1976)

Table 2 Ordovician range chart sources (Scotland) (for Figs8ndash10)


1 Rushton 2001b2 Rushton et al 19863 Rushton Tunnicliff amp Tripp 19964 Stone amp Rushton 19835 Stone amp Strachan 19816 Stone 19957 Williams 1982a8 Williams 19879 Williams 1988

10 Williams 199411 Zalasiewicz Rushton amp Owen 199512 Williams 1982b13 Floyd 199914 McMillan 200215 Floyd amp Rushton 199316 Barnes 200817 Stone amp Rushton 200318 Armstrong et al 199819 Rushton 2003a20 Rushton 2003b21 Zalasiewicz et al 200022 Elles amp Wood 1901ndash191823 Toghill 1970b24 Williams et al 2004

Table 3 Silurian range chart sources (for Figs 11ndash19)


1 Baker 19812 Cocks amp Toghill 19733 Davies 19294 Elles amp Wood 1901ndash19185 Harris J H unpub PhD thesis Univ

Cambridge 19876 Hutt 1974ndash19757 Hutt amp Rickards 19708 Loydell 1991b9 Loydell amp Cave 1993

10 Loydell 1992ndash1993a11 Loydell amp Cave 199612 Packham 196213 Rickards 197014 Rickards 197615 Strachan 199716 Toghill 1968a17 Zalasiewicz 1992b18 Zalasiewicz amp Tunnicliff 199419 Zalasiewicz 199420 Zalasiewicz Loydell amp Storch 199521 Zalasiewicz 199622 Zalasiewicz amp Williams 199923 Zalasiewicz 199524 BGS Scottish Sheet Memoir 4 (Kirkowan)25 BGS Scottish Sheet Memoir 5 (Kirkcudbright)26 BGS Scottish Sheet Memoir 9 (Thornhill)27 Stone 199528 Davies et al 199729 White et al 199230 Bull amp Loydell 199531 BGS Sheet Memoir 165 (Montgomery)32 Zalasiewicz Williams amp Akhurst 200333 Toghill 1968b34 Rickards Hutt amp Berry 197735 Sudbury 195836 Chopey-Jones Williams amp Zalasiewicz 200337 Williams et al 2003b38 Cullum amp Loydell 199639 Storch amp Loydell 199240 Storch amp Serpagli 199341 Loydell 199042 Wilson D R unpub PhD thesis Univ

Birmingham 195443 Loydell 1993b



Table 4 Index to taxa OEWno = OrdovicianEngland and Walestaxon number in range chart (Figs 3ndash7) OScno =OrdovicianScotlandtaxon number in range chart (Figs 8ndash10) Sno = Siluriantaxon number in range chart (Figs 11ndash19)

A Didymograptus sp (Skevington) OEW100A Monoclimacis sp (Rickards) S260A Paradelograptus sp (Rushton et al) OSc5A Pseudisograptus sp (Jenkins) OEW79abbreviatus Orthograptus OSc139 OEW234abbreviatus Rastrites S223acanthus Glossograptus OEW120acinaces Huttagraptus S41acuminatus Parakidograptus acuminatus S11acutidens Acrograptus OEW105acutus Didymograptus OEW110acutus Glyptograptus tamariscus S99acutus Orthograptus calcaratus OSc43 OEW188admirabilis lsquoMonograptusrsquo S185adunca Monoclimacis S327affinis Acrograptus OEW103alabamensis Dicellograptus OSc30alector Dicellograptus OSc129alternis Glyptograptus S96altissimus Parapetalolithus S227amii Tetragraptus OSc25 OEW24amplexicaulis Orthograptus OSc85 OEW200anceps Dicellograptus OSc136 OEW238angel Pseudisograptus OEW81anglica Rhabdinopora flabelliformis OEW7anglicus Oelandograptus austrodentatus OEW101anguinus Streptograptus S302angulatus Dicellograptus OSc83angulatus Glyptograptus tamariscus S78angulatus Pseudoclimacograptus OEW135angustatus Climacograptus OEW111angustidens Retiolites S282angustus Normalograptus OEW201 OSc105 S5angustifolius Pseudophyllograptus OSc23 OEW38ansulosus Streptograptus S192antennarius Cryptograptus OEW99antennularius Monograptus S346antiquus Climacograptus OSc63 OEW156 211 (aff)apiculatus Orthograptus OSc77 OEW180approximatus Tetragraptus OSc1arctus Amplexograptus OEW185 OSc75Darcuatus Torquigraptus S267argenteus Monograptus S133argutus Pribylograptus argutus S68armatus Glossograptus OEW115 OSc75Gartus Didymograptus OEW129ascendens Leptograptus OSc75Bascensus Akidograptus OEW248 S10ashgillensis Orthograptus amplexicaulis OEW237askerensis Tetragraptus bigsbyi OSc10atavus Atavograptus S31attenuatus Baltograptus vacillans OEW26attenuatus Glyptograptus S48auctus Pristiograptus S372auritus Glyptograptus S217austerus Monograptus austerus S66australis Isograptus caduceus OSc17avitus Glyptograptus OSc151 OEW242 S4

B Paradelograptus sp (Rushton et al) OSc13B Orthograptus sp (Cocks amp Toghill) S76balticus Didymograptus OEW27barbatus Comograptus S171barrandei Streptograptus S233barriei Pseudoglyptograptus S119basilica Monoclimacis S313basilicus Orthograptus calcaratus OSc106 OEW206becki Stimulograptus S245bekkeri Climacograptus OEW191belgica Rhabdinopora flabelliformis OEW5bellulus Rivagraptus S124bicornis Climacograptus OSc62 OEW189bicornis Monograptus austerus S77bifidus Didymograptus OEW125biformis Climacograptus OEW104

bigsbyi Tetragraptus bigsbyi OEW87bimucronatus Hallograptus OSc41bjerreskovae Monograptus S210bjerringus Pristiograptus S235bohemicus Bohemograptus S381bohemicus Cyrtograptus S334bornholmensis Barrandeograptus S297bouceki Plectograptus S353brevicaulis Dicranograptus OSc46 OEW166brevis Monograptus brevis S97brevis Normalograptus OSc66 OEW153bryograptoides Rhabd flabelliformis OEW8

cabanensis lsquoOrthograptusrsquo S18caduceus Dicellograptus OSc113caduceus Isograptus OEW76caelatus Amplexograptus OEW139calcaratus (group) Orthograptus OSc70 OEW198calicularis Corynoides OSc79cambriensis Dicellograptus OEW165capillaris Leptograptus OSc125capillaris Paradiversograptus S150 186capillaris Thamnograptus OSc37capis lsquoMonograptusrsquo S123carnicus Rastrites S195carnicus Torquigraptus S255carruthersi Barrandeograptus S342carruthersi Dicellograptus OSc121caudatus Ensigraptus OSc91 OEW214cautleyensis Mediograptus S322cavei Torquigraptus S230celticus Dicranograptus OSc46Acentrifugus Cyrtograptus S325cerastus Monograptus S127ceryx Atavograptus OEW245 S1changyangensis Monograptus S122chimaera Saetograptus chimaera S396chrysalis Monograptus S117ciliatus Glossograptus OEW193cirrus Coronograptus S60clathrospinosus Spinograptus S382clavatus Parapetalolithus S190clevensis Pseudoclimacograptus OEW231clingani Dicranograptus clingani OSc92 OEW213clingani Campograptus S148clintonensis Stimulograptus S258clunensis Saetograptus S399coelebs Azygograptus OEW116colonus Saetograptus colonus S379cometa Cephalograptus cometa S149communis Campograptus communis S106compactus Amplexograptus OSc57 OEW207compactus Saetograptus colonus S387complanatus Dicellograptus OSc127complexus Dicellograptus OSc134 135concinnus Pristiograptus S90confertus Amplexograptus OEW106confertus Dimorphograptus confertus S39contortus Oktavites S180conveniens Parapetalolithus S194convolutus Lituigraptus S142 154costatus Lasiograptus OSc64 OEW179crateriformis Glyptograptus sinuatus S172craticulus Plegmatograptus OSc140crenularis Monoclimacis S145crenulata Monoclimacis S287crinitus Crinitograptus S390crispus lsquoMonograptusrsquo S256crucifer Tetragraptus OEW57cucullus Aulograptus OEW97cumbrensis Pseudobryograptus OEW54cumbrensis Undulograptus OEW98cuneatus Glyptograptus S64curtus Corynoides OSc84 OEW182cyathiformis Dicranograptus OSc75F



Table 4 (Cont)

cyperoides Rivagraptus S81cyphus Coronograptus S42

daironi Pseudoretiolites S203danbyi Mediograptus S321davidensis Isograptus ovatus OEW145daviesi lsquoGlyptograptusrsquo OSc95 OEW224deani Holograptus OEW48decens Didymograptus OEW31decipiens Torquigraptus decipiens S157decipiens Tetragraptus OSc2decoratus Diplograptus OEW152decussatus Dimorphograptus decussatus S32deflexus Corymbograptus OEW36delicatulus lsquoMonograptusrsquo S163densus Dichograptus maccoyi OSc21densus Phyllograptus OEW65dentatus Eoglyptograptus OEW102denticulatus Torquigraptus S151denticulatus Orthoretiograptus OSc144desmograptoides Rhabd flabelliformis OEW2deubeli Monograptus S373difformis Monograptus S73diffusus Trochograptus OEW28diminutus Neodiplograptus S14directa Monoclimacis S276discus Monograptus (=Cochlogr veles) S265distans Glyptograptus tamariscus S74distans Rastrites S261distans Stimulograptus S165distinctus Expansograptus OEW78divaricatus Dicellogr divaricatus OSc47 OEW155divergens Adelograptus OEW40divergens Amphigraptus divergens OSc124divergens Isograptus victoriae OEW74dorotheus Climacograptus OSc107 OEW222doveri Thamnograptus OEW88drepanoformis Monograptus S280dubitatus Didymograptus OEW113dubius Dabashanograptus S222dubius Pristiograptus dubius S339dumosus Pseudisograptus OEW82

eiseli Paraplectograptus S360eivionicus Azygograptus OEW49elegans Dicellograptus elegans OSc123elegans Glyptograptus S108elegans Pterograptus OEW140ellesae Cyrtograptus S356ellesi Azygograptus OEW52ellesi Diplograptus OEW112elleswoodae Pseudoplegmatograptus S266elongatus Dimorphograptus S20elongatus Neodiplograptus S26elongatus Parapetalolithus S211enodis Glyptograptus enodis S80ensiformis Pseudotrigonograptus OSc19 OEW62epilongissimus Dimorphograptus S36erectus Dimorphograptus S30erectus Rastrites hybridus S156euglyphus Normalograptus OSc54 OEW154euodus Didymograptus OEW130excentricus Oktavites S299exiguus Streptograptus S257exilis Dicellograptus sextans OSc48 OEW176extensus Expansograptus OSc15extenuatus Rhaphidograptus S27extraordinarius Climacograptus OSc149extrema Cephalograptus cometa S161extremus Monograptus triangulatus S93

falx Oktavites S292fasciculatus Nicholsonograptus OEW137fastigatus Glyptograptus S213 221 (aff)fastigata Anticostia OSc133fibratus Neurograptus OSc97filiformis Acrograptus OSc4 OEW29

filiformis Streptograptus S215fimbriatus Glossograptus OEW122fimbriatus Monograptus triangulatus S104firmus Monograptus firmus S338flabelliformis Rhabdinopora flabelliformis OEW4flaccidus Leptograptus OSc80flemingii Monograptus S349flexilis Monograptus S350flexuosus Dicellograptus OSc86 OEW215flexuosus Mediograptus S329flittoni Mediograptus S314flumendosae Monoclimacis S347foliaceus Diplograptus OSc78 OEW151folium Petalolithus S139formosus Dicellograptus OSc35fragilis Pristiograptus fragilis S57fragilis Trichograptus OEW133fritschi Saetograptus fritschi S385fruticosus Tetragr (Pendeograptus) OSc6 OEW22fugax Rastrites S216furcatus Dicranograptus OSc44

galaensis Monoclimacis S252geinitzi Monoclimacis S298geintizii Rastrites S126geinitzianus Reteograptus OSc56geinitzianus Retiolites S268geminus Didymograptus OEW126gemmatus lsquoMonograptusrsquo S202geniculatus Dicellograptus OSc27 OEW158geniculatus Pseudisograptus OEW89geometricus Expansograptus OSc8gerhardi Monograptus S369gibberulus Isograptus OEW75giganteus Parapetalolithus S228glanfredensis Stimulograptus S200globosus Parapetalolithus S218glossograptoides Pseudophyllograptus OEW114goldschmidti Expansograptus OEW61gracilis Acrograptus OEW46gracilis Atavograptus S24gracilis Cyrtograptus lundgreni S359gracilis Nemagraptus OSc31 OEW168gracilis Rastrites S178grandis Stomatograptus S291grayae Lapworthograptus S289gregarius Coronograptus gregarius S58griestoniensis Monoclimacis S278guerichi Spirograptus S206

halli Stimulograptus S197hamatus Cyrtograptus S363harknessi Lasiograptus OSc68 OEW199harpago Campograptus lobiferus S162haupti Monoclimacis S394headi Tetragraptus OEW70hemmanni Monoclimacis S300hians Adelograptus OEW11hicksii Azygograptus OEW51hincksii Glossograptus hincksii OSc60 OEW181hipposideros Coronograptus S63hirundo Expansograptus OEW71hispanicus Parapetalolithus S224hollingworthi Diplograptus OEW134hopkinsoni Cryptograptus OEW93hughesi Metaclimacograptus S131hunnebergensis Adelograptus OEW10huttae Pristiograptus S244hybridus Rastrites hybridus S160

imago Monograptus S132imitatus Isograptus caduceus OEW77incertus Glyptograptus S50 (aff) 113incipiens Saetograptus leintwardinensis S395 403incisus Leptograptus validus OSc75Cinclinatus Monograptus radotinensis S343



Table 4 (Cont)

incommodus Pribylograptus S34 (aff) 56inconspicuus Mediograptus S319 (aff) 326incurvus Corynoides OSc89indivisus Normalograptus OEW241inflexus Corymbograptus OEW86infrequens Acrograptus OEW50initialis Pristiograptus S283initialis Pseudisograptus OSc20innotatus Paraclimacograptus OEW247 S16insectiformis Pseudorthograptus S112insectus Cyrtograptus S316instrenuus Monograptus S345intermedius lsquoMonograptusrsquo S111intermedius Orthograptus truncatus OSc98intortus Dicellograptus OSc59 OEW159involutus Torquigraptus S125irregularis Dicranograptus OSc28 OEW157isknos Pseudoclimacograptus OSc76 OEW194

jaculum Pristiograptus S135jaegeri Pristiograptus S365 (aff) 367johnsonae Streptograptus S239johnstrupi Dicellograptus OEW228jonesi Pribylograptus S129

kettneri Monoclimacis S328kindlei Tetragraptus OSc12knockensis Lapworthograptus S288kunmingensis Corymbograptus OEW34kurcki Acrograptus OEW55kurcki Parapetalolithus S168

lanceolatus Appendispinograptus OEW221lapworthi Azygograptus OEW59lapworthi Cyrtograptus S312largus Pristiograptus S309latus Amplexograptus OSc143latus Glyptograptus enodis S88latus Pristiograptus S340latus Petalolithus palmeus S92lautus Plegmatograptus OSc145lawsoni Holoretiolites (Balticograptus) S371leei Coronograptus S62leintwardinensis Saetograptus leintw S405lentus Holmograptus OEW119lepidus Corymbograptus uniformis OEW68leptotheca Diplograptus OSc73 OEW177leptotheca Pribylograptus S136limatulus Monograptus S141linearis Climacograptus tangshanensis S84linearis Expansograptus extensus OEW69linearis Glyptograptus tamariscus S75linearis Pleurograptus OSc119 OEW229lineatus Climacograptus antiquus OSc88linnaei Rastrites S196linnarssoni Cyrtograptus S354linnarssoni Monoclimacis S296linterni Torquigraptus S175lobiferus Campograptus S134lofuensis Xiphograptus OSc22logani Loganograptus OEW63longicaulis Dicranograptus ramosus OSc94longispinus Appendispinograptus OSc142longispinus Rastrites S105longissimus Dimorphograptus S37longus Stomatograptus S269loydelli Streptograptus S270 279ludensis Monograptus S370ludlowiensis Pristiograptus dubius S368lui Pleurograptus OSc137lundgreni Cyrtograptus lundgreni S358

macer Leptograptus flaccidus OSc110macilentus Leptograptus flaccidus OSc120macilentus Plectograptus S375magnificus Torquigraptus S176magnus Neodiplograptus S115

magnus Pseudoclimacograptus angulatus OEW141major Monograptus triangulatus S101margaritatus Neurograptus OSc103 OEW220marri Monograptus S232maximus Isograptus victoriae OEW67maximus Rastrites S214 226 (aff)medius Normalograptus OEW246 S6meridionalis Climacograptus OEW197micidus Pseudoclimacograptus angulatus OEW142micracanthus Orthograptus pageanus OEW217micropoma Monoclimacis S392millepeda Campograptus S130minimus Dicranograptus furcatus OSc55 OEW172minor Dicellograptus OSc131minor Dicranograptus nicholsoni OSc78A OEW205minor Petalolithus S98minor Pristiograptus S402minor Pseudotrigonograptus OEW60minusculus Coronograptus gregarius S29minutus Didymograptus OEW43minutus Streptograptus nanshanensis S174miserabilis Didymograptus OEW131lsquomiserabilis C rsquo (=N angustus) OSc105 OEW201 S5modestus Neodiplograptus modestus S15modestus Pseudoclimacograptus OSc50 OEW163moffatensis Dicellograptus OSc104mohawkensis Normalograptus OSc112 OEW208molestus Amplexograptus OEW186morleyae Mediograptus S318morrisi Dicellograptus OSc116 OEW223mucronatus Hallograptus OSc39 OEW174multiplex Temnograptus OEW20murchisoni Cyrtograptus SS335murchisoni Didymograptus OEW144murrayi Araneograptus OEW15mutabilis Pseudorthograptus S46 (aff) 54

nanus Didymograptus OEW138nanus Isograptus caduceus OEW107Anassa Gothograptus S366nebula Glyptograptus S238nebula Plegmatograptus OSc109 OEW230nicholsoni Acrograptus nicholsoni OEW124nicholsoni Dicranogr nicholsoni OSc67 OEW190nicholsoni Glyptograptus OSc132nicoli Monoclimacis griestoniensis S323nikolayevi Normalograptus S44nilssoni Neodiversograptus S378nitidus Expansograptus OEW72nobilis Hallograptus bimucronatus OSc75Enobilis Pseudophyllograptus OEW128nodifer Streptograptus S304normalis Normalograptus OSc141 OEW235 S7norvegicus Anisograptus OEW13notabilis Diplograptus OSc29nudus Pristiograptus S251

obesus Pseudoplegmatograptus obesus S181obtusus Campograptus S169occidentalis Glyptograptus OSc130 OEW233octobrachiatus Dichograptus OEW33orbatus Monograptus uncinatus S374ornatus Dicellograptus OSc148ovatoelongatus Petalolithus S91ovatus Parapetalolithus S191

pacificus Paraorthograptus OSc147packhami Glyptograptus S167pageanus Orthograptus OSc96pakrianus Didymograptus OEW127palmeus Parapetalolithus palmeus S225parabola Rhabdinopora flabelliformis OEW1parapriodon Monograptus S293partiliter Dimorphograptus decussatus S33parvulus Normalograptus OEW244 OSc152 S3patula Rhabdinopora flabelliformis OEW6patulosus Dicellograptus OEW204 OSc38



Table 4 (Cont)

pauperatus Climacograptus OEW143pauperatus Orthograptus truncatus OSc111 OEW218peggyae Neodiplograptus S116pendens Tetragraptus (Pendeograptus) OEW45penna Cystograptus S49peregrinus Rastrites S138perexcavatus Amplexograptus OSc72 OEW184perfectus Rastrites S189pergracilis Torquigraptus S284perlatus Pseudoretiolites S159perneri Cyrtograptus S355persculptus Normalograptus OEW243 S2pertenuis Nemagraptus explanatus OSc32petilus Streptograptus S246phleoides Rastrites S147phylloides Rogercooperia OSc75physophora Dimorphograptus S38pilatus Diplograptus OSc87planus Acrograptus nicholsoni OEW90planus Torquigraptus S231plumosus Streptograptus S208plurithecatus lsquoGlyptograptusrsquo OEW196pluto Didymograptus OEW123pollex Normalograptus OEW212postlethwaitei Tetragraptus OEW44praeanceps Dicellograptus OEW236praecedens Parapetalolithus S183praecursor Monograptus austerus S100praecursor Sigmagraptus OSc11praedubius Pristiograptus S332praematurus Huttagraptus S21praematurus Parakidograptus acuminatus S8praenuntius Expansograptus OEW58praestrachani Huttagraptus S22pragensis Torquigraptus pragensis S274 285 (group)prantli Pristiograptus S303predecipiens Monograptus triangulatus S82primulus Isograptus OEW41primulus Petalolithus S120primus Neodiplograptus modestus S13primus Saetograptus leintwardinensis S404pringlei Dicellograptus OSc78Bpriodon Monograptus S253priodonflemingii group Monograptus S349priscus Orthograptus calcaratus OEW147pristinus Corynoides OSc36pristinus Pristiograptus S198pristinus Pristiograptus fragilis S47progenitor Cucullograptus (Lobograptus) S386proteus Torquigraptus S249protobalticus Didymograptus OEW18protobifidus Didymograptus OEW95protoindentus Didymograptus OSc14protomurchisoni Didymograptus OSc9pseudobecki Streptograptus S247pseudobigsbyi Tetragraptus OSc26 OEW25pseudocommunis Monograptus S277pseudocultellus Monograptus S317pseudolatus Pristiograptus dubius S351pseudoplanus Monograptus S102pseudoruncinatus Streptograptus S209pseudovenustus lsquoGlrsquo pseudovenustus OSc150pulchellus Barrandeograptus S311pulcherrimus lsquoMonograptusrsquo S188pulcherrimus Orthoretiolites OSc128pumilus Dicellograptus OSc101pusillus Lasiograptus OEW183putillus Climacograptus OEW192

quadribrachiatus Tetragraptus OSc3 OEW23quadrimucronatus Orthograptus OSc102 OEW219quasimodo Kiaerograptus OEW14

radiatus Amphigraptus divergens OSc100radotinensis Monograptus radotinensis S333ramosus Cyrtograptus S362ramosus Dicranograptus OSc69 OEW173

ramosus Diversograptus S294rarus Neodiplograptus S28reclinatus Tetragraptus OSc16 OEW32rectangularis Normalograptus S19rectus Dicranograptus OSc49 OEW167rectus Paradiversograptus S193regius Parapetalolithus S219regularis Pristiograptus S158remotus Mediograptus S336renaudi Pristiograptus S204resicis Dicranograptus clingani OEW209reticulatus Pseudoplegmatograptus S263reticulatus Schizograptus OEW42retroflexus Monograptus S348retroversus Clinoclimacograptus S79retusus Lasiograptus OEW148revolutus Monograptus revolutus S67rhayaderensis Pseudoglyptograptus S85rheidolensis Monograptus brevis S95riccartonensis Monograptus S341richteri Lituigraptus S142rickardsi Monograptus S250rigens Dicellograptus elegans OSc122rigoletto Acrograptus OEW19rigidus Cyrtograptus S352rigidus Dicellograptus divaricatus OSc45robustus Expansograptus OEW109roemeri Saetograptus S383rostratus Campograptus communis S107runcinatus Paradiversograptus S207ruzickai Torquigraptus pragensis S272

salopiensis Dicellograptus OSc40 OEW164salweyi Saetograptus chimaera S391sandersoni Pribylograptus S55sarmentosus Adelograptus OEW12sartorius Streptograptus S271 (aff) 273scalaris Normalograptus S137scanicus Cucullograptus (Lobograptus) S389schaeferi Cryptograptus tricornis OEW107scharenbergi Pseudoclimacograptus OSc61 OEW136schaueri Parapetalolithus S242schaueri Rastrites S187schucherti Pristiograptus S243scoticus Thamnograptus OSc37sebyensis Pseudoclimacograptus angulatus OEW149sedberghensis Monograptus firmus S344sedgwickii Dichograptus octobrachiatus OEW35sedgwickii Stimulograptus S177semispinosus Saetograptus chimaera S397separatus Dichograptus OEW37separatus Monograptus triangulatus S89sequens Monograptus austerus S94sequens Pribylograptus argutus S166serpens Corynoides OSc74serra Tetragraptus OSc7 OEW64serratulus Acrograptus OSc33serratus Glyptograptus S140setiger Rastrites S109setosus Pseudoclimacograptus OSc34sextans Dicellograptus sextans OSc42 OEW178sheldoni Climacograptus OEW161shelvensis Eoglyptograptus OEW94shottoni Monoclimacis S315similis Expansograptus OEW39similis Monograptus triangulatus S86simplex lsquoClimacograptusrsquo S170simplex Lobograptus S388simulans Expansograptus OEW56simulatus Monograptus S324sinensis Acrograptus OEW16sinicus Undulograptus OEW91sinuatus Glyptograptus sinuatus S59slalom Metaclimacograptus S52socialis Orthograptus OSc126socialis Rhabdinopora flabelliformis OEW3sparsus Expansograptus OEW96



Table 4 (Cont)

speciosus Didymograptus OEW146speciosus Streptograptus S307spengillensis Rastrites distans S236spina Rastrites S146spinifer Dicranograptus ramosus OSc53 OEW187spinifer Leptograptus flaccidus OSc114spiniferus Climacograptus OSc93 OEW216spinigerus O quadrimucronatus OSc108 OEW210spinosus Spinograptus S377spinulosus Didymograptus OEW117spiralis Oktavites S295spiraloides Torquigraptus tullbergi S275stabilis Didymograptus OEW121stenostoma Pseudoclimacograptus OSc78Cstorchi Streptograptus S237strachani Huttagraptus S51strachani Streptograptus S205styloideus Climacograptus OSc118 OEW232sublinnarssoni Monoclimacis S306subtilis Nemagraptus OEW162 OSc31Asudburiae Monograptus S70suecicus Expansograptus OEW85supernus Appendispinograptus OSc138 OEW239supernus Glyptograptus S212superstes Expansograptus OSc52 OEW170svalbardensis Xiphograptus OEW83swanstoni Dimorphograptus confertus S45

tailbertensis Climacograptus OEW118tamariscoides Normalograptus S103tamariscus Glyptograptus tamariscus S53tardifurcatus Schizograptus OEW53tardiusculus Dicranograptus OSc75Atenellus Adelograptus OEW9tenuicornis Orthograptus calcaratus OSc90 OEW202tenuis Bohemograptus bohemicus S401tenuis Glyptograptus S24tenuis Neolagarograptus S164tenuis Parapetalolithus S248tenuis Streptograptus S241tenuissimus lsquoMonograptusrsquo S118teretiusculus Hustedograptus OSc51 OEW160testis Testograptus S361textor Sokolovograptus S353thuringiacus Neodiplograptus S121toernquisti Rhaphidograptus S40triangulatus Monograptus triangulatus S87tricornis Cryptograptus tricornis OSc65 OEW150trifilis Normalograptus S9tuberculatus Climacograptus OEW240 S12tubulariformis Cephalograptus S144tubuliferus Climacograptus OSc117 OEW227

tullbergi Torquigraptus tullbergi S281tumescens Pristiograptus S400turriculatus Spirograptus S240typus Phyllograptus OEW73

ultimus Corynoides OSc115 OEW225undulatus Metaclimacograptus S71undulatus Stimulograptus S153unguiferus Monograptus S376uniformis Corymbograptus OEW80uplandicus Orthograptus OEW169urbanekii Cyrtograptus S357urceolinus Torquigraptus S143urceolus Monograptus S173utilis Stimulograptus S234

validus Azygograptus OEW21validus Leptograptus validus OEW175 OSc36A (sl)variabilis Pristiograptus S179varians Glyptograptus tamariscus S69varians Saetograptus varians S380varicosus Corymbograptus OEW30vas Pseudoglyptograptus S110v-deflexus Yutagraptus OSc24velatus Nymphograptus OSc146veles Cochlograptus (=M discus) S265vesiculosus Cystograptus S17vesiculosus Stimulograptus S305v-fractus Corymbograptus v-fractus OEW47vicinus Pristiograptus S393victoriae Isograptus victoriae OSc18 OEW66vikensis Monoclimacis S330volucer Corymbograptus v-fractus OEW84vomerina Monoclimacis vomerina S290vulgaris Monograptus austerus S61vulgatus Orthograptus calcaratus OSc82 OEW203

walkerae Monograptus brevis S83wandalensis Saetograptus S384welchae Pristiograptus S398wenlockianus Pseudoplegmatograptus S337whitei Streptograptus S254whitfieldi Orthograptus OSc58 OEW171williamsi Pseudostreptograptus S229wilsoni Climacograptus OSc81wilsoni Parapetalolithus S264wimani Streptograptus S308woodae Monoclimacis S286wyensis Normalograptus S65

ziczac Dicranograptus OSc71 OEW195

Acknowledgements The authors wish to thank MikeMelchin and Petr Storch for their meticulous and carefulrefereeing that has considerably improved this text LisaBarber and Mateusz Zalasiewicz for help with producing thefigures and Jane Holland and Lori Snyder for their patientand painstaking editorial work

References

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BAKER S J 1981 The graptolite biostratigraphy ofa Llandovery outlier near Llanystumdwy GwyneddNorth Wales Geological Magazine 118 355ndash65

BARCLAY W J DAVIES J R HUMPAGE A J WATERS RA WILBY P R WILLIAMS M amp WILSON D 2005

Geology of the Brecon district ndash A brief explanationof the geological map Sheet Explanation of the BritishGeological Survey 150 000 Sheet 213 Brecon (Englandand Wales)

BARNES R P 2008 Geology of the Whithorn Kirkcowan andWigtown district memoir for 150000 geological sheets2 4W and 4E (Scotland) Nottingham UK BritishGeological Survey 146 pp

BARRANDE J 1850 Graptolites de Boheme Published bythe author Prague

BASSETT M G 1985 Towards a lsquoCommon Languagersquo instratigraphy Episodes 8 87ndash92

BASSETT M G RICKARDS R B amp WARREN P T 1975The type Wenlock Series Report of the Institute ofGeological Sciences 7513 indashiv 1ndash19

BATES D E B amp KIRK N H 1984 Autecology of Siluriangraptoloids Special Papers in Palaeontology 32 121ndash39

BATES D E B amp KIRK N H 1985 Graptolites a fossil case-history of evolution from sessile colonial animals to



automobile superindividuals Proceedings of the RoyalSociety of London Series B 228 207ndash24

BECKLY A J 1988 The stratigraphy of the Arenig Series inthe Aberdaron to Sarn area western Llyn North WalesGeological Journal 23 321ndash37

BECKLY A J amp MALETZ J 1991 The Ordovician graptolitesAzygograptus and Jishougraptus in Scandinavia andBritain Palaeontology 34 887ndash925

BERGSTROM S M LOFGREN A amp MALETZ J 2004 TheGSSP of the Second (Upper) Stage of the Lower Or-dovician Series Diabasbrottet at Hunneberg Provinceof Vastergotland Southwestern Sweden Episodes 27265ndash72

BERRY W B N amp BOUCOT A J 1972 Silurian graptolitedepth zonation Proceedings of the 24th InternationalGeological Congress Montreal 7 59ndash65

BETTLEY R FORTEY R A amp SIVETER D J 2001 High-resolution correlation of Anglo-Welsh Middle to UpperOrdovician sequences and its relevance to internationalchronostratigraphy Journal of the Geological SocietyLondon 158 937ndash52

BJERRESKOV M 1975 Llandoverian and Wenlockian grap-tolites from Bornholm Fossils amp Strata 8 94 pp

BOLTON J 1899 The palaeontology of the Manx Slatesof the Isle of Man Memoirs and Proceedings of theManchester Literary and Philosophical Society 43 1ndash15

BOUCEK B 1953 Biostratigraphy development and correl-ation of the Zelkovice and Motol Beds in the Silurian ofBohemia Sbornık Ustrednıho Ustavu Geologickeho 20473ndash80

BOUCEK B 1960 Einige Bemerkungen zur Entwicklung derGraptolithenfaunen in Mitteldeutschland und BohmenGeologie 9 556ndash64

BRIDGE D MCC CARNEY J N LAWLEY R S ampRUSHTON A W A 1998 The geology of the countryaround Coventry and Nuneaton Memoir of the BritishGeological Survey Sheet 169 (England and Wales) x +185 pp London The Stationery Office

BULL E E amp LOYDELL D K 1995 Uppermost Telychiangraptolites from the North Esk Inlier Pentland Hillsnear Edinburgh Scottish Journal of Geology 31 163ndash70

BULMAN O M B 1944ndash1947 A monograph of theCaradoc (Balclatchie) graptolites from limestones inLaggan Burn Ayrshire Monograph of the Palaeon-tographical Society London (1) 1945 1ndash42 pls 1ndash3 (2) 1946 43ndash58 pls 4ndash6 (3) 1947 indashxi 59ndash78pls 7ndash10

BULMAN O M B 1963 On Glyptograptus dentatus(Brongniart) and some allied species Palaeontology 6665ndash89

BULMAN O M B 1964 Lower Palaeozoic planktonQuarterly Journal of the Geological Society of London120 455ndash76

BULMAN O M B amp RUSHTON A W A 1973 Tremadocfaunas from boreholes in Central England Bulletin ofthe Geological Survey of Great Britain no 43 1ndash40 7pls

CAVE R 1979 Sedimentary environments of the basinalLlandovery of mid-Wales In Caledonides of the BritishIsles Reviewed (eds A L Harris C H Holland amp BE Leake) pp 517ndash26 Geological Society of LondonSpecial Publication no 8

CAVE R amp HAINS B A 1986 Geology of the countrybetween Aberystwyth and Machynlleth Memoir of theBritish Geological Survey Sheet 163 (England andWales)

CAVE R amp HAINS B A 2001 Geology of the countryaround Montgomery and the Ordovician rocks of theShelve area Memoir for 150 000 Sheet 165 with partof Sheet 151 (Welshpool) (England and Wales) LondonThe Stationery Office

CAVE R amp RUSHTON A W A 1996 The Llandeilo(Ordovician) Series in the core of the Twyi AnticlineLlanwrtyd Powys UK Geological Journal 31 47ndash60

CHOPEY-JONES A WILLIAMS M amp ZALASIEWICZ J A2003 Biostratigraphy palaeobiogeography and mor-phology of the Llandovery graptolites Campograp-tus lobiferus (MrsquoCoy) and Campograptus harpago(Tornquist) Scottish Journal of Geology 39 71ndash85

CHURKIN M CARTER C amp JOHNSON B R 1977Subdivision of Ordovician and Silurian time scale usingaccumulation rate of graptolite shale Geology 5 452ndash6

COCKS L R M amp TOGHILL P 1973 The biostratigraphyof the Silurian rocks of the Girvan District ScotlandJournal of the Geological Society London 129 209ndash43

COCKS L R M WOODCOCK N H RICKARDS R BTEMPLE J T amp LANE P D 1984 The Llandovery Seriesof the type area Bulletin of the British Museum (NaturalHistory) Geology 38 131ndash82

COOPER A H FORTEY N J HUGHES R A MOLYNEUXS G MOORE R M RUSHTON A W A amp STONEP 2004 Skiddaw Group of the English Lake DistrictMemoir of the British Geological Survey London TheStationery Office

COOPER A H RUSHTON A W A MOLYNEUX S GMOORE R M amp WEBB B C 1995 The stratigraphycorrelation provenance and palaeogeography of theSkiddaw Group (Ordovician) in the English LakeDistrict Geological Magazine 132 185ndash211

COOPER R A 1979 Sequence and correlation of Tremadocgraptolite assemblages Alcheringa 3 7ndash19

COOPER R A 1999 Ecostratigraphy zonation and globalcorrelation of earliest Ordovician planktic graptolitesLethaia 32 1ndash16

COOPER R A amp LINDHOLM K 1990 A precise worldwidecorrelation of early Ordovician graptolite sequencesGeological Magazine 127 497ndash525

COOPER R A NOWLAN G S amp WILLIAMS S H 2001Global Stratotype Section and Point for the base of theOrdovician System Episodes 24 19ndash28

COOPER R A amp SADLER P M 2004 The OrdovicianPeriod In A Geological Time Scale 2004 (eds F MGradstein J G Ogg amp A G Smith) pp 165ndash87Cambridge University Press

CULLUM A A amp LOYDELL D K 1996 A new speciesof Neodiplograptus from the Middle Llandovery of theRheidol Gorge Wales Journal of the Czech GeologicalSociety 41 217ndash19

DAVIES J R FLETCHER C J N WATERS R A WILSOND WOODHALL D G amp ZALASIEWICZ J A 1997Geology of the country around Llanilar and RhayaderMemoir of the British Geological Survey Sheets 178and 179 (England and Wales)

DAVIES J R WATERS R A WILBY P R WILLIAMSM amp WILSON D 2003 Geology of the Cardiganand Dinas island district ndash A brief explanation ofthe geological map Sheet Explanation of the BritishGeological Survey 150000 Sheet 193 (including partof Sheet 210) Cardigan and Dinas Island (England andWales)

DAVIES K A 1929 Notes on the graptolite faunas ofthe Upper Ordovician and Lower Silurian GeologicalMagazine 66 1ndash27



ELLES G L 1900 The zonal classification of the WenlockSeries of the Welsh Borderland Quarterly Journal ofthe Geological Society of London 56 370ndash414

ELLES G L 1925 The characteristic assemblages ofthe graptolite zones of the British Isles GeologicalMagazine 62 337ndash47

ELLES G L 1933 The Lower Ordovician graptolite faunaswith special reference to the Skiddaw Slates Summaryof Progress Geological Survey of Great Britain (for1932) 94ndash111

ELLES G L 1937 The classification of the Ordovician rocksGeological Magazine 74 481ndash95

ELLES G L 1940 The stratigraphy and faunal successionin the Ordovician rocks of the BuilthndashLlandrindodinlier Radnorshire Quarterly Journal of the GeologicalSociety of London 95 383ndash445

ELLES G L amp WOOD E M R 1901ndash1918 A monographof British graptolites London The PalaeontographicalSociety

ERDTMANN B D 1976 Ecostratigraphy of Ordoviciangraptoloids In The Ordovician System (ed M GBassett) pp 621ndash43 Cardiff University of Wales Pressand National Museum of Wales

FINNEY S C 1986 Graptolite biofacies and the correlationof eustatic subsidence and tectonic events in the Middleto Upper Ordovician of North America Palaios 1 453ndash61

FINNEY S C amp BERGSTROM S M 1986 Biostrati-graphy of the Ordovician Nemagraptus gracilis ZoneIn Palaeoecology and biostratigraphy of graptolites(eds C P Hughes amp R B Rickards) pp 47ndash59Geological Society of London Special Publicationno 20

FINNEY S C amp BERRY W B N 1997 New perspectiveson graptolite distribution and their use as indicators ofplatform margin dynamics Geology 25 919ndash22

FLOYD J D 1999 Geology of the CarrickndashLoch Doondistrict British Geological Survey Memoir for 150 000sheets 8W and 8E London The Stationery Office

FLOYD J D amp RUSHTON A W A 1993 Ashgill greywackesin the Southern Uplands of Scotland an extensionof the Ordovician succession in the Northern BeltTransactions of the Royal Society of Edinburgh EarthSciences 84 79ndash85

FLOYD J WILLIAMS M amp RUSHTON A W A 1999Late Ordovician (Ashgill) ostracodes from the Drum-muck Group Craighead Inlier Girvan District south-west Scotland Scottish Journal of Geology 35 15ndash24

FORTEY R A BECKLY A J amp RUSHTON A W A 1990International correlation of the base of the LlanvirnSeries Ordovician System Newsletters on Stratigraphy22 119ndash42

FORTEY R A HARPER D A T INGHAM J K OWENA W PARKES M A RUSHTON A W A ampWOODCOCK N H 2000 A Revised Correlation ofOrdovician Rocks in the British Isles Geological Societyof London Special Report no 24 83 pp

FORTEY R A HARPER D A T INGHAM J K OWENA W amp RUSHTON A W A 1995 A revision ofOrdovician series and stages from the historical typearea Geological Magazine 132 15ndash30

FORTEY R A amp OWENS R M 1978 Early Ordovicianstratigraphy and faunas of the Carmarthen districtsouth-west Wales Bulletin of the British Museum(Natural History) Geology 30 225ndash94

FORTEY R A amp OWENS R M 1987 The Arenig Series inSouth Wales Bulletin of the British Museum (NaturalHistory) Geology 41 69ndash307

FORTEY R A amp OWENS R M 1990 Arenig biostratigraphyand correlation in the Welsh Basin Journal of theGeological Society London 147 607ndash10

GIBBONS W amp MCCARROLL D 1993 Geology of the areaaround Aberdaron including Bardsey Island Memoirof the British Geological Survey sheet 133 (Englandand Wales) viii + 88 pp London HMSO

HALL J 1865 Graptolites of the Quebec Group Figures anddescriptions of Canadian organic remains GeologicalSurvey of Canada Dec 2 1ndash151 pls 1ndash21

HAMILTON B M 2001 Charles Lapworthrsquos ldquoThe MoffatSeriesrdquo Episodes 24 194ndash200

HARPER D A T amp WILLIAMS S H 2002 A relictOrdovician brachiopod fauna from the Parakidograptusacuminatus Biozone (lower Silurian) of the EnglishLake District Lethaia 35 71ndash8

HARPER J C 1956 The Ordovician succession near Llanys-tumdwy Caernarvonshire Liverpool and ManchesterGeological Journal 1 385ndash93

HOLLAND C H LAWSON J D amp WALMSLEY V G1963 The Silurian rocks of the Ludlow DistrictShropshire Bulletin of the British Museum (NaturalHistory) Geology 8 95ndash171

HOLLAND C H amp PALMER D C 1974 Bohemograptusthe youngest graptoloid known from the British Siluriansequence In Graptolite studies in honour of O M BBulman (eds R B Rickards D E Jackson amp C PHughes) pp 215ndash36 Special Papers in Palaeontology13 London The Palaeontological Association

HOLLAND C H RICKARDS R B amp WARREN P T1969 The Wenlock graptolites of the Ludlow DistrictShropshire and their stratigraphical significance Palae-ontology 12 663ndash83

HOPKINSON J 1873 On the occurrence of numerous speciesof graptolites in the Ludlow rocks of ShropshireGeological Magazine 10 519ndash20

HOWE M P A 1999 The Silurian fauna (graptolite andnautiloid) of the Niarbyl Formation Isle of Man In Insight of the suture the Palaeozoic geology of the Isle ofMan in its Iapetus Ocean context (eds N H WoodcockD G Quirk W R Fitches amp R P Barnes) pp 177ndash87Geological Society of London Special Publication no160

HOWELLS M F amp SMITH M 1997 The Geology ofthe Country around Snowdon Memoir of the BritishGeological Survey Sheet 119 (England and Wales)London The Stationery Office

HUGHES R A 1989 Llandeilo and Caradoc graptolites ofthe Builth and Shelve Inliers London The Palaeonto-graphical Society Publication 577 part of vol 141 for1987

HUGHES R A 1995 The durations of Silurian graptolitezones Geological Magazine 132 113ndash15

HUTT J E 1974ndash1975 The Llandovery graptolites of theEnglish Lake District London The PalaeontographicalSociety Publ 540 part of vol 128 (1974) 1ndash56 publ542 part of vol 129 (1975) 57ndash137

HUTT J E amp RICKARDS R B 1970 The evolutionof the earliest Llandovery monograptids GeologicalMagazine 107 67ndash77

INGHAM J K 1966 The Ordovician rocks in the Cautleyand Dent districts of Westmoreland and YorkshireProceedings of the Yorkshire Geological Society 35455ndash505

INGHAM J K 1979 The Moffat area In Guidebook to fieldmeeting Great Britain March 30ndashApril 11 1979 (edsM G Bassett L R M Cocks C H Holland J KIngham J D Lawson R B Rickards amp J T Temple)



pp 42ndash6 Subcommission on Silurian StratigraphyOrdovicianndashSilurian Boundary Working Group I UG S

INGHAM J K amp WRIGHT A D 1970 A revised classifica-tion of the Ashgill Series Lethaia 3 233ndash42

JACKSON D E 1962 Graptolite Zones in the Skiddaw Groupin Cumberland England Journal of Paleontology 36300ndash13

JACKSON D E 1978 The Skiddaw Group In The geology ofthe Lake District (ed F Moseley) pp 79ndash98 YorkshireGeological Society Occasional Publication no 3

JAEGER H 1959 Graptolithen und Stratigraphie derjungsten Thuringer Slurs Abhandlungen der DeutschenAkademie der Wissenschaften zu Berlin (Berlin 1959)1ndash197

JAEGER H 1991 Neue Standard-Graptolithenzonenfolgenach der lsquoGrossen Krisersquo an der WenlockLudlowGrenze (Silur) Neues Jahrbuch fur Geologie undPalaontologie Abhandlungen 182 303ndash54

JENKINS C J 1982 Isograptus gibberulus (Nicholson)and the isograptids of the Arenig Series (Ordovician)of England and Wales Proceedings of the YorkshireGeological Society 44 219ndash48

JENKINS C J 1983 The Ordovician graptolites from theGreat Paxton Borehole Cambridgeshire Palaeontology26 641ndash53

JENKINS C J 1987 The Ordovician graptolite Didymo-graptus murchisoni in south Wales and its use in three-dimensional absolute strain analysis Transactions of theRoyal Society of Edinburgh Earth Sciences 78 105ndash14

JONES H ZALASIEWICZ J A amp RICKARDS R B 2002Clingfilm preservation of spiraliform graptolites evid-ence of organically sealed Silurian seafloors Geology30 343ndash6

JONES O T 1909 The HartfellndashValentian succession inthe district around Plynlimon and Pont Erwyd (NorthCardiganshire) Quarterly Journal of the GeologicalSociety of London 65 463ndash537

JONES O T 1947 The geology of the Silurian rocks west andsouth of the Carneddau range Radnorshire QuarterlyJournal of the Geological Society of London 103 1ndash26

JONES O T amp PUGH W J 1916 The geology of the districtaround Machynlleth and the Llyfnant Valley QuarterlyJournal of the Geological Society of London 71 343ndash85

JONES O T amp PUGH W J 1935 The geology of the districtsaround Machynlleth and Aberystwyth Proceedings ofthe Geologistsrsquo Association 46 247ndash300

KIRK N H 1978 Mode of life of graptolites ActaPalaeontologica Polonica 23 533ndash55

KORENrsquo T N LENZ A C LOYDELL D K MELCHIN M JSTORCH P amp TELLER L 1996 Generalized graptolitezonal sequence defining Silurian time intervals forglobal palaeogeographic studies Lethaia 29 59ndash60

LANDING E BOWRING S A DAVIDEK K L RUSHTONA W A FORTEY R A amp WIMBLEDON W A P2000 Cambro-Ordovician boundary age and durationof the lowest Ordovician Tremadoc Series based onUndashPb zircon dates from Avalonian Wales GeologicalMagazine 137 485ndash94

LAPWORTH C 1878 The Moffat Series Quarterly Journalof the Geological Society of London 34 240ndash346

LAPWORTH C 1879ndash1880a The geological distribution ofthe Rhabdophora Annals and Magazine of NaturalHistory London (5) 3 (1879) 245ndash57 449ndash55 4 (1879)333ndash41 423ndash21 5 (1880) 45ndash62 273ndash85 358ndash69 6(1880a) 16ndash29 185ndash207

LAPWORTH C 1980b On new British graptolites Annals andMagazine of Natural History London (5) 5 149ndash77

LAPWORTH H 1900 The Silurian sequence of RhayaderQuarterly Journal of the Geological Society of London56 67ndash137

LENZ A C NOBLE P J MASIAK M POULSON S Ramp KOZŁOWSKA A 2006 The lundgreni ExtinctionEvent integration of paleontological and geochemicaldata from Arctic Canada GFF 128 153ndash8

LINDHOLM K 1991 Ordovician graptolites from the earlyHunneberg of Southern Scandinavia Palaeontology 34283ndash327

LINNARSSON J G O 1871 Om nagra forsteningar franSveriges och Norges Primordialzon Ofversikt af Kong-liga Vetenskaps-Akademiens Forhandlingar 6 789ndash97

LOYDELL D K 1990 On the type material of the Llandovery(Silurian) graptoloid Monograptus pseudobecki Boucekamp Pribyl 1942 and the speciesrsquo biostratigraphicalsignificance Scottish Journal of Geology 26 119ndash23

LOYDELL D K 1991a The biostratigraphy and formationalrelationships of the upper Aeronian and lower Telychian(Llandovery Silurian) formations of western mid-Wales Geological Journal 26 209ndash44

LOYDELL D K 1991b Dobrsquos Linn ndash the type locality ofthe Telychian (Upper Llandovery) Rastrites maximusBiozone Newsletters on Stratigraphy 25 155ndash61

LOYDELL D K 1992ndash1993a Upper Aeronian and lowerTelychian (Llandovery) graptolites from western mid-Wales London The Palaeontographical Society Publ589 for vol 146 (1992) 1ndash55 publ 592 for vol 147(1993) 56ndash180

LOYDELL D K 1993b Worldwide correlation of Telychian(Upper Llandovery) strata using graptolites In Highresolution stratigraphy (eds A E Hailwood amp R BKidd) pp 323ndash40 Geological Society of LondonSpecial Publication no 70

LOYDELL D K 2007 Graptolites from the Upper Ordovicianand Lower Silurian of Jordan Special Papers inPalaeontology 78 66 pp

LOYDELL D K amp CAVE R 1993 The Telychian (UpperLlandovery) stratigraphy of Buttington Brick Pit WalesNewsletters on Stratigraphy 29 91ndash103

LOYDELL D K amp CAVE R 1996 The LlandoveryndashWenlockboundary and related stratigraphy in eastern mid-Waleswith special reference to the Banwy River sectionNewsletters on Stratigraphy 34 39ndash64

LOYDELL D K amp MALETZ J 2004 The Silurian grap-tolite genera Streptograptus and PseudostreptograptusJournal of Systematic Palaeontology 2 65ndash93

LOYDELL D K STORCH P amp MELCHIN M J 1993 Tax-onomy evolution and biostratigraphical importance ofthe Llandovery graptolite Spirograptus Palaeontology36 909ndash26

MALETZ J 2001 A condensed Lower to Middle Ordoviciangraptolite succession at Matane Quebec CanadaCanadian Journal of Earth Sciences 28 1531ndash9

MALETZ J 2004 Discussion of Stone amp Rushton 2003Scottish Journal of Geology 40 185ndash7

MALETZ J RUSHTON A W A amp LINDHOLM K 1991 Anew early Ordovician didymograptid and its bearing onthe correlation of the Skiddaw Group of England withthe Toslashyen Shale of Scandinavia Geological Magazine128 335ndash43

MARR J E 1892 On the Wenlock and Ludlow strata of theLake District Geological Magazine Decade III vol IX534ndash41

MARR J E 1894 Notes on the Skiddaw Slates GeologicalMagazine Decade IV vol I 122ndash30



MARR J E amp NICHOLSON H A 1888 The StockdaleShales Quarterly Journal of the Geological Society ofLondon 44 654ndash732

MCMILLAN A 2002 Geology of the New Galloway andThornhill district Memoir for 150 000 GeologicalSheets 9W and 9E (Scotland) London The StationeryOffice

MELCHIN M J 1989 Llandovery graptolite biostratigraphyand paleobiogeography Cape Phillips Island CanadianArctic Islands Canadian Journal of Earth Sciences 261726ndash46

MELCHIN M J 2007 Biostratigraphic and palaeobiogeo-graphic significance of some Aeronian (Lower Silurian)graptolites from the Arisaig Group Nova ScotiaCanada Acta Palaeontologica Sinica 46 (supp) 311ndash19

MELCHIN M J COOPER R A amp SADLER P M 2004 TheSilurian Period In A Geologic Time Scale 2004 (eds FM Gradstein J G Ogg amp A G Smith) pp 188ndash201Cambridge University Press

MELCHIN M J amp DEMONT M E 1995 Propulsionmodes in the Graptoloidea a new model for graptolitelocomotion Paleobiology 21 110ndash20

MITCHELL C E 1987 The evolution and classification ofthe Diplograptacea Palaeontology 30 353ndash405

MITCHELL C E GOLDMAN D KLOSTERMAN S LMALETZ J SHEETS H D amp MELCHIN M J 2007Phylogeny of the Ordovician Diplograptoidea ActaPalaeontologica Sinica 46 (supp) 332ndash9

MOLYNEUX S G amp RUSHTON A W A 1988 The age ofthe Watch Hill Grits English Lake District structuraland palaeogeographical implications Transactions ofthe Royal Society of Edinburgh Earth Sciences 79 43ndash69

MULLINS G L amp ALDRIDGE R J 2004 Chitinozoanbiostratigraphy of the basal Wenlock Series (Silurian)Global Stratotype Section and Point Palaeontology 47745ndash73

NICHOLSON H A 1868 On the graptolites of the ConistonFlags Quarterly Journal of the Geological Society ofLondon 24 521ndash45

OGG J G OGG G amp GRADSTEIN F M 2008 The concisegeologic time scale Cambridge University Press 177pp

OLD R A SUMBLER M G amp AMBROSE K 1987 Geologyof the country around Warwick Memoir of the BritishGeological Survey Sheet 184 (England amp Wales) viii+ 93 pp London HMSO

OWENS R M FORTEY R A COPE J C W RUSHTONA W A amp BASSETT M G 1982 Tremadoc faunasfrom the Carmarthen district South Wales GeologicalMagazine 119 1ndash38

PACKHAM G H 1962 Some Diplograptids from the BritishLower Silurian Palaeontology 5 498ndash526

PAGE A ZALASIEWICZ J A WILLIAMS M amp POPOVL E 2007 Were transgressive black shales a neg-ative feedback modulating glacioeustasy in the EarlyPalaeozoic Icehouse In Deep-Time Perspectives onClimate Change Marrying the Signal from ComputerModels and Biological Proxies (eds M Williams AM Haywood F J Gregory amp D N Schmidt) pp123ndash56 The Micropalaeontological Society SpecialPublications London The Geological Society

PALMER D amp RICKARDS B (eds) 1991 Graptolites writingin the rocks Woodbridge UK The Boydell Press 182pp

PANNELL C L CLARKSON E N K amp ZALASIEWICZ J A2006 Fine-scale biostratigraphy within the Stimulograp-

tus sedgwickii Biozone (Llandovery Silurian) at DobrsquosLinn Southern Uplands Scottish Journal of Geology42 59ndash64

PEACH B N amp HORNE J 1899 The Silurian Rocks ofBritain Vol I Scotland Memoirs of the GeologicalSurvey of the United Kingdom HMSO

POREBSKA E KOZŁOWSKA-DAWIDZIUK A amp MASIAKM 2004 The lundgreni event in the Silurian ofthe East European Platform Poland PalaeogeographyPalaeoclimatology Palaeoecology 213 271ndash94

PRATT W T WOODHALL D G amp HOWELLS M F1995 Geology of the country around Cadair IdrisMemoir of the British Geological Survey Sheet149 (England amp Wales) ix + 111 pp LondonHMSO

PRIBYL A 1983 Graptolite biozones of the Kopanina andPridoli Formations in the Upper Silurian of centralBohemia Casopis pro Mineralogii a Geologii 28 149ndash67

RICKARDS R B 1964 The graptolitic mudstones andassociated facies in the Silurian strata of the HowgillFells Geological Magazine 10 435ndash51

RICKARDS R B 1965 New Silurian graptolites from theHowgill Fells Northern England Palaeontology 8 247ndash71

RICKARDS R B 1967 The Wenlock and Ludlow successionin the Howgill Fells (north-west Yorkshire and West-morland) Quarterly Journal of the Geological Societyof London 123 215ndash51

RICKARDS R B 1969 Wenlock graptolite zones in theEnglish Lake District Proceedings of the GeologicalSociety London 1654 61ndash5

RICKARDS R B 1970 The Llandovery (Silurian) graptolitesof the Howgill Fells Northern England London ThePalaeontographical Society

RICKARDS R B 1976 The sequence of Silurian graptolitezones in the British Isles Geological Journal 11 153ndash88

RICKARDS R B 1989 Exploitation of graptolite cladogen-esis in Silurian stratigraphy In A global standard for theSilurian System (eds C H Holland amp M G Bassett)pp 267ndash74 National Museum of Wales GeologicalSeries no 9 Cardiff

RICKARDS R B 1995 Utility and precision of Siluriangraptolite biozones Lethaia 28 129ndash37

RICKARDS R B 2002 The graptolitic age of the type AshgillSeries (Ordovician) Cumbria UK Proceedings of theYorkshire Geological Society 54 1ndash16

RICKARDS R B 2004 The significance of the graptoloidAmphigraptus divergens from the (mid-Rawtheyan) typesection of the Ashgill Series Ordovician GeologicalMagazine 141 735ndash8

RICKARDS R B amp DURMAN P N 2006 Evolution of theearliest graptolites and other hemichordates In Studiesin Palaeozoic palaeontology (eds M G Bassett amp VK Deisler) pp 5ndash92 National Museum of WalesGeological Series no 25 Cardiff

RICKARDS R B HUTT J E amp BERRY W B N 1977Evolution of the Silurian and Devonian graptoloidsBulletin of the British Museum (Natural History)Geology 28 1ndash120 pls 1ndash6

RICKARDS R B RIGBY S RICKARDS J amp SWALES C1998 Fluid dynamics of the graptolite rhabdosomerecorded by Laser Doppler Anemometry Palaeontology41 737ndash52

RIGBY S amp RICKARDS B 1990 New evidence for thelife habit of graptoloids from physical modellingPaleobiology 15 402ndash13



RIVA J 1976 Climacograptus bicornis bicornis (Hall)its ancestor and likely decendents In The OrdovicianSystem Proceedings of a Palaeontological Associationsymposium Birmingham September 1974 (ed M GBassett) pp 589ndash619 Cardiff University of WalesPress

RONG JIAUYU et al 2007 Final Report of the Subcom-mission on Silurian Stratigraphy Restudying the GlobalStratotype for the base of the Silurian Silurian Times14 10ndash13

RUSHTON A W A 1981 A polymorphic graptolite fromthe concealed Tremadoc rocks of England GeologicalMagazine 118 615ndash22

RUSHTON A W A 1982 The biostratigraphy and correl-ation of the MerionethndashTremadoc Series boundary inNorth Wales In The CambrianndashOrdovician boundarysections fossil distributions and correlations (eds M GBassett amp W T Dean) pp 41ndash59 National Museum ofWales Geological Series no 3 Cardiff

RUSHTON A W A 1990 Ordovician graptolite biostrati-graphy in the Welsh Basin a review Journal of theGeological Society London 147 611ndash14

RUSHTON A W A 1993 Graptolites from the Manx GroupProceedings of the Yorkshire Geological Society 49259ndash62

RUSHTON A W A 2001a The use of graptolites in thestratigraphy of the Southern Uplands Peachrsquos legacyTransactions of the Royal Society of Edinburgh EarthSciences 91 341ndash7

RUSHTON A W A 2001b The graptolite fauna of theSuperstes Mudstone Formation in the Ordovician of theGirvan Cover Sequence Scottish Journal of Geology 3745ndash52

RUSHTON A W A 2003a A new spiny species ofPseudoclimacograptus from the Ordovician of theSanquhar area Southern Uplands Scottish Journal ofGeology 39 41ndash4

RUSHTON A W A 2003b An addition to the graptolite faunaof the Superstes Mudstone Formation Girvan districtScottish Journal of Geology 39 87ndash8

RUSHTON A W A 2006 Multum ex parvo graptolites fromThrelkeld Quarry and their implications Proceedings ofthe Cumberland Geological Society 7 146ndash53

RUSHTON A W A amp MOLYNEUX S G 1989 Thebiostratigraphic age of the Ordovician Skiddaw Groupin the Black Combe inlier English Lake DistrictProceedings of the Yorkshire Geological Society 47267ndash76

RUSHTON A W A OWEN A W OWENS R M ampPRIGMORE J K 1999 British Cambrian to OrdovicianStratigraphy Geological Conservation Review Seriesno 18 Peterborough Joint Nature Conservation Com-mittee xxi + 435 pp (published 2000)

RUSHTON A W A STONE P amp HUGHES R A 1996Biostratigraphic control of thrust models for theSouthern Uplands of Scotland Transactions of theRoyal Society of Edinburgh Earth Sciences 86 137ndash52

RUSHTON A W A STONE P SMELLIE J L amp TUNNICLIFFS P 1986 An early Arenig age for the Pinbain sequenceof the Ballantrae Complex Scottish Journal of Geology22 41ndash54

RUSHTON A W A TUNNICLIFF S P amp TRIPP R P 1996The faunas of the Albany Group in the Girvan area andtheir palaeogeographical implications Scottish Journalof Geology 32 23ndash32

RUSHTON A W A amp ZALASIEWICZ J A 1999 A distinct-ive stratigraphically useful normalograptid graptolite

from the Caradoc of Eastern Avalonia Irish Journal ofEarth Sciences 17 83ndash90

SCHOFIELD D I DAVIES J R WATERS R A WILBYP R WILLIAMS M amp WILSON D 2004 Geologyof the Builth Wells district ndash a brief explanation ofthe geological map Sheet Explanation of the BritishGeological Survey 150 000 Sheet 196 Builth Wells(England and Wales)

SHERGOLD J H amp SHIRLEY J 1968 The faunal-stratigraphyof the Ludlovian rocks between Craven Arms andBourton near Much Wenlock Shropshire GeologicalJournal 6 119ndash38

SKEVINGTON D 1966 The morphology and systematics oflsquoDidymograptusrsquo fasciculatus Nicholson 1869 Geolo-gical Magazine 103 487ndash97

SKEVINGTON D 1970 A Lower Llanvirn graptolite faunafrom the Skiddaw Slates Westmorland Proceedings ofthe Yorkshire Geological Society 37 395ndash444

SKEVINGTON D 1973 Graptolite fauna of the Great PaxtonBorehole Huntingdonshire Bulletin of the GeologicalSurvey of Great Britain no 43 41ndash57 pls 8 9

SKEVINGTON D 1974 Controls influencing the compositionand distribution of Ordovician graptolite provincesSpecial Papers in Palaeontology 13 59ndash73

SKEVINGTON D amp JACKSON D E 1976 A new LlanvirnianIsograptus from the D murchisoni Shales of AbereiddyBay Wales Alcheringa 1 139ndash42

STONE P 1995 Geology of the Rhins of Galloway districtMemoir of the British Geological Survey Sheets 1 and3 (Scotland) London HMSO

STONE P amp RUSHTON A W A 1983 Graptolite faunas fromthe Ballantrae ophiolite complex and their structuralimplications Scottish Journal of Geology 19 297ndash310

STONE P amp RUSHTON A W A 2003 A Late Arenig (earlyYapeenian) graptolite fauna and the coeval tectonicdevelopment of the Ballantrae Complex ophiolite SWScotland Scottish Journal of Geology 39 29ndash40

STONE P amp RUSHTON A W A 2004 Response to Maletz(2004) Scottish Journal of Geology 40 187

STONE P amp STRACHAN I 1981 A fossiliferous boreholesection within the Ballantrae ophiolite Nature 293455ndash7

STORCH P 1994 Graptolite biostratigraphy of the LowerSilurian (Llandovery and Wenlock) of Bohemia Geolo-gical Journal 29 137ndash65

STORCH P 1996 Basal Silurian Akidograptus ascensusndashParakidograptus acuminatus Biozone in the peri-Gondwanan Europe graptolite assemblages its strati-graphical range and paleobiogeography Bulletin of theCzech Geological Survey 71 171ndash8

STORCH P 1998 Graptolites of the Pribylograptusleptotheca and Lituigraptus convolutus biozones ofTman (Silurian Czech Republic) Journal of the CzechGeological Society 43 209ndash72

STORCH P 2001 Graptolites stratigraphy and depositionalsetting of the middle Llandovery (Silurian) volcanic-carbonate facies at Hyskov (Barrandian area CzechRepublic) Bulletin of the Czech Geological Survey 7655ndash76

STORCH P amp LOYDELL D K 1992 Graptolites of theRastrites linnaei Group from the European Llandovery(Lower Silurian) Neues Jahrbuch fur Geologie undPalaontologie Abhandlungen 184 63ndash86

STORCH P amp LOYDELL D K 1996 The Hirnantiangraptolites Normalograptus persculptus and lsquoGlypto-graptusrsquo bohemicus stratigraphical consequences oftheir synonomy Palaeontology 39 869ndash81



STORCH P amp MASSA D 2006 Middle Llandovery (Aero-nian) graptolites of the western Murzuq Basin and AlQarqaf Arch region south-west Libya Palaeontology49 83ndash112

STORCH P amp SERPAGLI E 1993 Lower Silurian graptolitesfrom southwestern Sardinia Bollettino della SocietaPaleontologica Italiana 32 3ndash57

STRACHAN I 1971 A synoptic supplement to ldquoA monographof British Graptolitesrdquo by Miss G L Elles and Miss EM R Wood London The Palaeontographical Society

STRACHAN I 1986 The Ordovician graptolites of the ShelveDistrict Shropshire Bulletin of the British Museum(Natural History) Geology 40 1ndash58

STRACHAN I 1996ndash1997 A bibliographic index of Britishgraptolites (Graptoloidea) Parts 1 and 2 Monograph ofthe Paleontographical Society London 1ndash40 (Publ No600 part of Vol 150 for 1996) 41ndash155 (Publ No 603part of Vol 151 for 1997)

STRAHAN A CANTRILL T C DIXON E E L THOMAS HH amp JONES O T 1914 The geology of the South WalesCoalfield Part XI The country around HaverfordwestMemoir of the Geological Survey of England and Wales(Sheet 228) viii + 262 pp

STUBBLEFIELD C J amp BULMAN O M B 1927 TheShineton Shales of the Wrekin district with notes ontheir development in other parts of Shropshire andHerefordshire Quarterly Journal of the GeologicalSociety of London 83 96ndash146

SUDBURY M 1958 Triangulate monograptids from theMonograptus gregarius Zone (lower Llandovery) ofthe Rheidol Gorge (Cardiganshire) PhilosophicalTransactions of the Royal Society of London B241485ndash555

TELLER L 1969 The Silurian biostratigraphy of Polandbased on graptolites Acta geologica Polonica 19 393ndash501

TOGHILL P 1968a The graptolite assemblages and zonesof the Birkhill Shales (lower Silurian) at Dobbrsquos LinnPalaeontology 11 654ndash68

TOGHILL P 1968b The stratigraphical relationships of theearliest Monograptidae and the DimorphograptidaeGeological Magazine 105 46ndash51

TOGHILL P 1970a A fauna from the Hendre Shales(Llandeilo) of the Mydrim area CarmarthenshireProceedings of the Geological Society London 1663121ndash9

TOGHILL P 1970b Highest Ordovician (Hartfell Shales)graptolite faunas from the Moffat area south ScotlandBulletin of the British Museum (Natural History)Geology 19 1ndash26 pls 1ndash16

URBANEK A 1966 On the morphology and evolution ofCucullograptus (Monograptidae Graptolithina) Actageologica Polonica 11 291ndash544

VANDENBERG A H M amp COOPER R A 1992 The Or-dovician graptolite sequence of Australasia Alcheringa16 33ndash85

WADGE A J NUTT M J C amp SKEVINGTON D 1972Geology of the Tarn Moor Tunnel in the Lake DistrictBulletin of the Geological Survey of Great Britain 4155ndash73

WARREN P T 1971 The sequence and correlation ofgraptolite faunas from the WenlockndashLudlow rocksof north Wales Bureau Recherches Geologiques etMinieres Memoire 73 451ndash60

WARREN P T PRICE D NUTT M J C amp SMITH E G1984 Geology of the country around Rhyl and DenbighMemoir of the British Geological Survey Sheets 90 and97 and parts of 94 and 106 217 pp

WHITE D E BARRON H F BARNES R P amp LINTERNB C 1992 Biostratigraphy of late Llandovery (Tely-chian) and Wenlock turbiditic sequences in the SWSouthern Uplands Scotland Transactions of the RoyalSociety of Edinburgh Earth Sciences 82 297ndash322

WILLIAMS M DAVIES J R WATERS R A RUSHTON AW A amp WILBY P R 2003a Stratigraphicaland palaeoecological importance of Caradoc (UpperOrdovician) graptolites from the Cardigan area SWWales Geological Magazine 140 549ndash71

WILLIAMS M RUSHTON A W A WOOD B FLOYDJ D SMITH R amp WHEATLEY C 2004 A revisedgraptolite biostratigraphy for the lower Caradoc (UpperOrdovician) of southern Scotland Scottish Journal ofGeology 40 97ndash114

WILLIAMS M amp ZALASIEWICZ J A 2004 The WenlockCyrtograptus species of the Builth Wells district centralWales Palaeontology 47 223ndash63

WILLIAMS M ZALASIEWICZ J A RUSHTON A WA LOYDELL D K amp BARNES R P 2003b Anew stratigraphically significant Torquigraptus species(graptolite) from the Central Belt of the SouthernUplands Terrane Scotland Scottish Journal of Geology39 17ndash28

WILLIAMS S H 1982a Upper Ordovician graptolites fromthe top Lower Hartfell Shale Formation (D clinganiand P linearis zones) near Moffat southern ScotlandTransactions of the Royal Society of Edinburgh EarthSciences 72 229ndash55

WILLIAMS S H 1982b The late Ordovician graptolite faunaof the Anceps Bands at Dobrsquos Linn southern ScotlandGeologica et Palaeontologica 16 29ndash56

WILLIAMS S H 1983 The OrdovicianndashSilurian boundarygraptolite fauna of Dobrsquos Linn southern ScotlandPalaeontology 26 605ndash39

WILLIAMS S H 1986 Top Ordovician and lowest Silurianof Dobrsquos Linn In Palaeoecology and biostratigraphyof graptolites (eds C P Hughes amp R B Rickards)pp 165ndash71 Geological Society of London SpecialPublication no 20

WILLIAMS S H 1987 Upper Ordovician graptolites fromthe D complanatus Zone of the Moffat and Girvandistricts and their significance for correlation ScottishJournal of Geology 23 65ndash92

WILLIAMS S H 1988 Dobrsquos Linn ndash the OrdovicianndashSilurianboundary stratotype Bulletin of the British Museum ofNatural History (Geology) 43 17ndash30

WILLIAMS S H 1994 Revision and definition ofthe C wilsoni graptolite Zone (middle Ordovi-cian) of southern Scotland Transactions of theRoyal Society of Edinburgh Earth Sciences 85143ndash57

WILLIAMS S H amp STEVENS R K 1988 Early Ordovician(Arenig) graptolites of the Cow Head Group westernNewfoundland Palaeontographica Canadiana 5 1ndash167

WOOD E M R 1900 The Lower Ludlow Formation and itsgraptolite-fauna Quarterly Journal of the GeologicalSociety of London 56 415ndash92

WOOD E M R 1906 The Tarannon Series of TarannonQuarterly Journal of the Geological Society of London62 644ndash701

YOUNG T GIBBONS W amp MCCARROLL D 2002 Geologyof the country around Pwllheli Memoir of the BritishGeological Survey sheet 134 (England and Wales) x +151 pp London The Stationery Office

ZALASIEWICZ J A 1984 A re-examination of the typeArenig Series Geological Journal 19 105ndash24


850 Graptolites in British stratigraphy

ZALASIEWICZ J A 1986 Graptolites from the type ArenigSeries Geological Magazine 123 537ndash44

ZALASIEWICZ J A 1990 Silurian graptolite biostratigraphyin the Welsh Basin Journal of the Geological SocietyLondon 147 619ndash22

ZALASIEWICZ J A 1992a Graptolite dating of Ordovicianvulcanicity in the Arenig area North Wales GeologicalJournal 27 379ndash89

ZALASIEWICZ J A 1992b Two new graptolites fromthe early Silurian (Llandovery Aeronian) of centralWales an origin for monoclimacid thecal morphologyGeological Magazine 126 779ndash85

ZALASIEWICZ J A 1994 Middle to late Telychian (SilurianLlandovery) graptolite assemblages of central WalesPalaeontology 37 375ndash96

ZALASIEWICZ J A 1995 The structure and affinities ofLapworthograptus grayae (Lapworth 1876) ScottishJournal of Geology 31 29ndash36

ZALASIEWICZ J A 1996 Aeronian (Silurian Landovery)graptolites from central Wales Geologica et Palaeonto-logica 30 1ndash14

ZALASIEWICZ J A 2001 Graptolites as constraints onmodels of sedimentation across Iapetus a reviewProceedings of the Geologistsrsquo Association 112 237ndash51

ZALASIEWICZ J A amp HOWE M P A 2003 A case ofprofound astogenetic metamorphosis the structure and

affinities of Awarograptus nodifer (Tornquist 1881)Scottish Journal of Geology 39 45ndash9

ZALASIEWICZ J A LOYDELL D K amp STORCH P1995 A taxonomic revision of three mid-Telychianmonoclimacids Journal of Paleontology 69 961ndash967

ZALASIEWICZ J A amp RUSHTON A W A 2008 Atlas ofGraptolite Type Specimens Folio 2 London Palaeon-tographical Society

ZALASIEWICZ J A RUSHTON A W A HUTT J E ampHOWE M P A 2000 Atlas of Graptolite Type Speci-mens Folio 1 London Palaeontographical Society

ZALASIEWICZ J A RUSHTON A W A amp OWEN A W1995 Late Caradoc graptolitic faunal gradients acrossthe Iapetus Ocean Geological Magazine 132 611ndash17

ZALASIEWICZ J A amp TUNNICLIFF S P 1994 UppermostOrdovician to Lower Silurian graptolite biostratigraphyof the Wye Valley Central Wales Palaeontology 37695ndash720

ZALASIEWICZ J A amp WILLIAMS M 1999 Graptolitebiozonation of the Wenlock (Silurian) rocks of the BuilthWells district central Wales Geological Magazine 136263ndash83

ZALASIEWICZ J A WILLIAMS M amp AKHURST M2003 An unlikely evolutionary lineage the Rhud-danian (Silurian Llandovery) graptolites Huttagraptuspraematurus and Coronograptus cyphus re-examinedScottish Journal of Geology 39 89ndash96



Figure 1 British Ordovician graptolite biozones and subzones Zonal scheme based on that proposed by Fortey et al (1995) andadopted in the Ordovician Correlation Report of Fortey et al (2000) with subsequent modification to the Arenig to early Llanvirn byCooper et al (2004) refinement of the Caradoc by Bettley Fortey amp Siveter (2001) while the CaradocAshgill section of Englandand Wales shows the modified correlations suggested by Rickards (2002) Chronostratigraphy and radiometric dates after Ogg Ogg ampGradstein (2008)










3 Taxonomy






4 Preservation



















































8 Ordovician


























































































































































































































9 Silurian

























































































































































































Table 4 (Cont)











Table 4 (Cont)












Table 4 (Cont)








Table 4 (Cont)









References













































































































































































































































































3 Taxonomy






4 Preservation



















































8 Ordovician


























































































































































































































9 Silurian

























































































































































































Table 4 (Cont)











Table 4 (Cont)












Table 4 (Cont)








Table 4 (Cont)









References



















































































































































































































































































































8 Ordovician


























































































































































































































9 Silurian

























































































































































































Table 4 (Cont)











Table 4 (Cont)












Table 4 (Cont)








Table 4 (Cont)









References



























































































































































































































































































































































































































































































9 Silurian

























































































































































































Table 4 (Cont)











Table 4 (Cont)












Table 4 (Cont)








Table 4 (Cont)









References





































































































































































































































































graptolites in british stratigraphy

Documents