Records of the Western AlIstralIaIl Museum Supplement No. 57: 331-340 (1999).

The taphonomy of the Lancefield swamp megafaunal accumulation,Lancefield, Victoria

Sanja Van Huet

Department of Earth Sciences, Monash University, Clayton, Vic 3168;email: ST-huet@mail.earth.monash.edu.au

Abstract - The late Quaternary megafa unal assemblage at Lancefield,Victoria, was deposited by fluvial transportation processes. Evidence forpredepositional weathering of the bones indicates a prolonged period ofexposure prior to transportation and burial.

The sediments associated with the bone bed indicate a high energy flowregime, which would have contributed to the abrasion found on the majorityof the bones, and to the destruction and / or removal of larger fragile elementsand those from small animals; neither of which are found within the deposit.

New dates on bones and teeth of about 40,000 BP differ significantly fromthe maximum date of 26,000 BP for the bone bed, and tend to confirm that thebones at Lancefield constitute a secondary or reworked deposit.

INTRODUCTION

The Lancefield megafaunal accumulation islocated on the outskirts of the township ofLancefield, 70 km north-northeast of Melbourne, at37°16'S., 144°44'E., in swamp deposits fed by flowfrom the water-table underlying the Pliocene-agedbasalts that blanket the surrounding area.

Palaeontological investigations at Lancefieldswamp began after large fossil bones wererecovered by I.P. Mayne during excavations for awell in 1843, at what is now known as the MayneSite. Subsequent excavations by WilliamBlandowski in 1850 and Sir Frederick McCoy in1858 were abandoned due to the over-abundantflow of ground water (Orchiston et al. 1977). Thefirst accounts of the deposit were published by E.C.Hobson, Curator of the National Museum ofVictoria (now Museum Victoria) (Hobson 1845),and N. Taylor, Government Surveyor (Taylor 1863).

In 1973 the Classic Site at Lancefield swamp wasdiscovered through the efforts of geologist RobinGlenie, and was extensively excavated by a teamcomprising archaeologists from Sydney Universityand the Institute of Aboriginal Studies, Canberra,and palaeontologists from the National Museum ofVictoria and Monash University. In 1974 furtherfield work was undertaken in an attempt to providea "sharper focus on the time of the [megafaunal]extinctions" (Gillespie et al. 1978). Two subsequentexcavations were undertaken in 1975 and 1976 (T.H.Rich pers. comm. 1993). This work resulted inpublications by Horton (1976), Ladd (1976),Orchiston et al. (1977), Gillespie et al. (1978), Hortonand Samuel (1978), and Horton and Wright (1981).

The findings of Gillespie et al. (1978) included twodates of 26,000 years BP from the channel fill at thebase of the bone-bearing sequence. This wasconsidered contemporaneous with occupation ofthe area by humans, on the basis of the discovery ofa large quartzite blade in situ within the bone bed.Other findings included some evidence for watercontrolling the distribution and local orientation ofbones, and that bones showed little evidence forexposure prior to deposition and burial. Gillespie etal. (1978) also noted that there was little evidencefor small-sized species. They argued that this wasnot " ... the biased result of some post-mortemsorting process" but rather "This remarkablyrestricted species list, of large species only, showsthat some special selective event was causingdeath".

In 1984, the Sou th Site was discovered andexcavated by a team from the Museum of Victoriaand Brigham Young University, Utah, USA. Theirfindings were recorded in an unpublished MonashUniversity project report by Munro (1984).

A new excavation was undertaken in 1991 by theauthor to assess the influence of water sorting inmore detail, to try to identify the "special selectiveevent" that occurred at Lancefield swamp and toattempt to discover an age for the bones, rather thanthe sediments, within the bone bed (Van Huet1993). Only the South and Mayne Sites weresampled during this field season, due to problemsobtaining access to the Classic Site. This paper isbased upon the results of that investigation (VanHuet 1994a, 1994b), and a new dating studyundertaken by Van Huet et al. (1998).

332 S. Van Huet

Figure 1 Fossil phalanges from Lancefield swamp showing variation in the extent of transportational abrasion (fromleft to right): no abrasion (0%); little abrasion (1-4%); some abrasion (4-8%); well abraded (8-12%); veryabraded (>12%); cf. Table 1. Scale bar = 1 cm.

MATERIALS AND METHODS

The South and Mayne Sites were relocated byhand augering in a grid sequence to the level of thechannel fill / bone bed recorded by previousworkers (between 1.5 and 2 m below the surface).Where bone was recovered in the auger, pits weredug to the upper stratigraphic boundary of the bonebed. Lateral excavation followed the observeddirection of each bone deposit.

In situ bone material was exposed with handtrowels, small scrapers and fingers. The orientationof each bone was recorded prior to removal fromthe matrix and its relative position in thestratigraphy was noted. All bones were washed inwater, soaked in a dilute emulsion of polyvinylchloride in water, to assist with preservation, andair dried prior to packing for transport. Very fragilespecimens were brushed with a concentratedemulsion of polyvinyl chloride. All matrix from thebone layer was collected, soaked in a water/detergent mix overnight and the resulting slurrywas washed, passed through 1 mm and 3 mmsieves and the screen residues air dried prior tosorting in the laboratory.

Fragments of Diprotodon incisors from the SouthSite were collected for radiocarbon, amino acidracemization (AAR) and electron spin resonance(ESR) analysis. A sample of in situ charcoal from theSouth Site was also collected for radiocarbon dating.

To date, approximately half of the faunal materialfrom the 1991 excavation has been catalogued intothe vertebrate palaeontological collections of theMuseum Victoria (MY). Other material is on displayin the Department of Earth Sciences, MonashUniversity.

The fossil bones were identified to family, and

species where possible. Each element was assessedfor transportational wear (percentage abrasion), thepresence of cracking and flaking caused bypredepositional weathering processes and obvioussigns of carnivory such as puncture and gnawmarks (e.g. Marshall1989).

Abrasion was assessed using a descriptive scalethat estimated the percentage of the elementremoved through abrasive damage, and assessmentwas made for each bone, relative to all other bonesin the sample (Table 1 and Figures 1 and 2).

Figure 2 Fossil phalanx from Lancefield swamp whichhas been abraded to a bone pebble (>12%abrasion). Scale bar = 1 cm.

Taphonomy of Lancefield megafauna 333

Table 1 Descriptive terminology, percentage wear and diagnostic features used in the appraisal of abrasion of boneelements from the South and Mayne Sites, Lancefield.

Term

one

Little

Some

Well

Very

Estimated% Wear

0% of bone lost to abrasion

1-4% of bone lost to abrasion

4-8% of bone lost to abrasion

8-12% of bone lost to abrasion

>12% of bone lost to abrasion

Diagnostic Features

No abrasion is evident. Recognition ofdiagnostic features - excellent.

Articular facets, processes and other articular surfacesdisplay a small degree of smoothing. Recognition ofdiagnostic features - very good.

Processes displaying the inner bone fibre. The shafts oflonger bones display areas of abrasion.Recognition of diagnostic features - satisfactory.

Outer layer of bone completely removed from processes,long bones displaying abrasion to this degree areprobably incomplete. Recognition of diagnosticfeatures - poor.

Bone pebble formed, almost all diagnostic features havebeen removed through abrasion. All surfaces of the bonewill display some degree of abrasion.

The presence of cracking and flaking on the fossilbones (Figure 3), symptomatic of predepositionalweathering, was assessed using criteria fromBehrensmeyer (1978). Behrensmeyer observed thatbones " ... freed of covering tissue and exposed onthe ground surface usually undergo rather rapidchanges in appearance ..." (bone decomposition).These changes include flaking (where the outerlayers of the bone peel away in an 'onion skin'fashion) and cracking (where, initially, surface, thendeepening cracks occur in the bones parallel to thebone fibre). This decomposition, especially inadvanced stages, renders the bones highlysusceptible to fragmentation.

Behrensmeyer (1978) identified six progressivestages of predepositional bone weathering, whichcan be summarized as: Stage 0 - no sign ofcracking or flaking; Stage 1 - cracking; Stage 2 ­flaking; Stage 3 - entire bone surface roughened(shallow); Stage 4 - entire bone surface roughened(penetrates inner cavities); Stage 5 - bones fallingapart in situ.

The weathering stages have been outlined herebecause their features occur on many of the bonesfrom Lancefield swamp. However, only thepresence or absence of weathering features has beennoted, as the Lancefield bones do not progressivelyfollow Behrensmeyer's scale of weathering. (Forexample, flaking occurs independently of crackingin over 80% of the bones from Lancefield.)Behrensmeyer's 'Stage' sequence was studied undersavanna conditions in the Amboseli Basin in Kenyaand is not wholly transferable to temperateAustralian conditions.

Minimum numbers of individuals (MNI) for theClassic and South Sites have been taken from theliterature: Gillespie et al. (1978) and Munro (1984)

Figure 3 Fossil phalanges from Lancefield swampshowing evidence of predepositionalweathering. Note longitudinal flaking andcracking parallel to the bone fibre. Scale bar =1 cm.

334

Depth inMetres

0.5

, .0

1.5

2.0

2.5

Soil androot mat

Grey andyellowmottled clay

Denseblackclay

Green andyellowmottledclaywith bones

European, mostlybrown clay soil (I)

Black clay, few bones,microliths near base (11)

Bones, green!grey to black clay (Ill)

Black mottled clay,quartz, bones (IV)

Channel fill (V)

10Cm root matBrown clay soil

Blackglutinousclay

Mottled grey/greenclay, lenses of pebblesand bone shards

Main bone bed, unsortedsediments, mottledgrey/green clay

S. Van Huet

Coarse fibrous peat,little clay or topsoil

Water saturated blackclay, some gravels andquartz clasts

Black clay, gravels,bone and bone shards

.... = Bones

3.

Classic Site(after Ladd 1976)

Classic Site(after Gillespie et al. 1978)

South Site(this work)

Mayne Site(this work)

Figure 4 Stratigraphic profiles for the three Sites at Lancefield swamp. L1 to L4 indicate pollen zones defined by Ladd(1976). Roman numerals in brackets indicate the horizons defined by Gillespie et al. (1978).

for the Classic Site; Munro (1984) for the South Site.MNI for the Mayne Site were based on cranial anddentary elements identified to species level, becausethese provide highly recognizable characteristics foridentification, and dentary elements are the mostrobust, most abundant and best preserved in theSite.

RESULTS

StratigraphyLancefield swamp contains a sequence of distinctive

sedimentary horizons, whose total thickness exceeds3.5 m (Figure 4). The stratigraphy found in the SouthSite was comparable to that described for the Classic

Figure 5 Clasts from the fossil bone bed, Lancefield swamp. The sediments are highly unsorted, atypical of swampdeposits. Scale in centimetres.

Taphonomy of Lancefield megafauna

Site by Ladd (1976) and Gillespie et al. (1978), but thatof the Mayne Site was not.

South SiteThe top horizon consists of soil and plant root

mats, consistent with typical results of Europeanagriculture (Ladd 1976). 1l1is is underlain across theSite by an amorphous, glutinous black clay with 5­10°/', by volume organic content, typical of a paludaldeposit (Alien and Collinson 1986).

1l1e layer directly below this is a mottled grey /green, dense, inorganic, anoxic clay whichgradually grades into the main bone bed. Bothdeposits contain 'floating' isolated pockets or lensesof fossil bones, quartz gravels and other lithic clasts.The total thickness of these two horizons is morethan 2.4 m at their northern end. The boundarybetween the black and grey / green clay horizons isundulating but clearly defined. The channel fill,which is of limited horizontal extent (Gillespie et al.1978), was not observed in the South Site.

Mayne SiteThe upper 1 m is composed of a coarse, fibrous,

peat-like mat with little inorganic sediment. 1l1is isdirectly underlain by a water-saturated, ungleyed,black clay within which fossil bones are randomlyscattered. The lack of differentiated grey/green claylayers and the presence of bones throughout the depthof the black clay are consistent with a stratigraphyresulting from disturbance and backfilling at the timeof the Mayne excavation in 1843. This is confirmed bythe finding, during the 1991 excavation, of a 2 msquare area delineated by axe-hewn posts within thebone bed, and, next to various diprotodontid fossils,

N

-- .,. 1 specimen

Figure 6 Rose diagram of orientations of long axes ofelongate bones in the South Site, Lancefieldswamp.

335

some old strips of leather, a glass "H.P. Sauce" bottleand broken crockery. Elsewhere in the swamp suchEuropean artefacts are restricted to the upper brownclay (Gillespie et al. 1978).

Sedimentology

South SiteEvidence for fluvial transport is seen within the

grey / green clay horizon associated with the bonedeposit. The clay contains lenses of texturally andcompositionally immature sediments, which can belikened to an unconsolidated litharenite (Pettijohnet al. 1972: 158). The clasts (Figure 5) range from siltto pebble size, are highly unsorted, and generallyunrounded. They appear to be of mixed provenancewith granite, quartz, feldspar and pisolitic lateritenodules all present within the clay matrix. Theseclasts are only associated with fossil bone, and donot occur elsewhere. They are not characteristic ofpaludal deposits, but instead indicate fluvialtransport processes.

A rose diagram plot of the orientation of longbones in this Site (Figure 6), shows a strong south­southwest to north-northeast trend, concurring withgeneral drainage in the area.

Mayne SiteThis Site displays a similar range of clasts to that

of the South Site, but they are distributedchaotically throughout the black clay horizon.

Long bone orientation is also chaotic at this Site

N

-- ,.. 1 specimen

Figure 7 Rose diagram of orientations of long axes ofelongate bones in the Mayne Site, Lancefieldswamp.

336 S. Van Huet

(Figure 7), and is consistent with most of the sitehaving been previously disturbed and backfilledduring the Mayne excavation in 1843.

Table 2 Results from dating samples collected duringthe 1991 excavations from the South Site,Lancefield swamp, (data from Van Huet et al.1998).

0 None

0 Little

El Some

• Well

• Very

Maxillae (c.)Maxillae (in.)

Mandibles (c.)Mandibles (in.)

Dorsal y'brae (c.)Dorsal y'brae (in.)

Caudal y'brae (c.)Caudal y'brae (in.)

Ribs (c.)Ribs (in.)

Scapulae (c.)Scapulae (in.)

Humeri (c.)Humeri (In.)

Ulnae (c.)Ulnae (in.)

Radii (c.)Radii (in.)

Metatarsi (c.)Metatarsi (in.)

Pubes (c.)Pubes (in.)

Tibiae (c.)Tibiae (in.)

Astragali (c.)Astragali (in.)

Calcanea (c.)Calcanea (in.)

Metapodia (c.)Metapodia (in.)

Phalanges (c.)Phalanges (in.)

0

Figure 8 Levels of abrasion recorded on the combinedsamples of skeletal elements of all mammalspecies from the South and Mayne Sites,Lancefield swamp, collected during the 1991field season, divided into complete (c.) andincomplete (in.) elements. "Dorsal v'brae"includes cervical, thoracic and lumbarvertebrae. Phalanges include those from bothmanus and pes, which were notdifferentiated.

20 40 60 80 100

Number of specimens

in the extent of abrasion indicates either differentlengths of time in transportation (as evident whencomparing abrasion on similar elements) ordifferences in robustness between elements.

No evidence of skeletal articulation or articulationby association was found. No bones of small-sizedanimals were recovered from either the South orMayne Sites during the 1991 excavations.

It is acknowledged that the feeding habits ofcarnivores or scavengers such as Sarcophilu5 sp. andthe accumulation of bone fragments in seats, canproduce similar characteristics on bone (Douglas etal. 1966; Marshall and Cosgrove 1990) as thoseproduced by predepositonal subaerial weathering.However, such activity is not considered to be thecause of the bone accumulation for three reasons.

Firstly, the distinctive sedimentary matrix

Result (yr BP)Method Sample no. Material dated

14(: Wk-2565 Charcoal 14950 ± 124D14(: N2-4191 Tooth apatite 27250± 30014(: NZ-4424 Tooth apatite 27210 ± 210FSR ANU-1052A Diprotodon incisor 50100 ±9700FSR ANU-1052B Diprotodon incisor 46300 ± 8900FSR ANU-1052C Diprotodon incisor 56000 ± 10800AAR UWGA Diprotodon incisor 4DSOO ± 11000AAR UWGA Diprotodon incisor 3400J ±9SOO

DatingDates obtained from samples collected from the

South Site are given in Table 2. From these resultsVan Huet et al. (1998) concluded that theradiocarbon ages are a minimum for the apatite andhence the teeth are likely to prove older; 50,000 BPis a best average estimate of the age of theDiprotodon from the ESR results; and the AARresults indicate an age in the range 30-50,000 BP.

The radiocarbon date on charcoal of 14950 ± 1240BP (Wk-2565) obtained from within the bone bed atthe South Site, has a very large error, rendering itimprecise, but it may indicate the time of lastdeposition of the bone material in that part ofLancefield swamp (Van Huet et al. 1998).

Taphonomic resultsUp to 96% of some skeletal elements from the

South and Mayne Sites show some degree ofabrasion and/or predepositional weathering.Elements vary in completeness from small match­sized splinters to complete bones 215 mm in length.The bulk of the collected material comprisessplinters or shards of bone which are typicallyunidentifiable (e.g. Klein and Cruz-Uribe 1984: 17).Complete, or near complete, elements are theexception. Heavier, more robust bones from largerspecies tend to be less fragmented.

Abrasion is greater on vertebrae, metatarsals andmaxillae and less on the robust and compactly­shaped phalanges and mandibles (Figure 8). Themost common elements are phalanges, metatarsals,mandibles and single molars from Macropu5 titan.Elements such as crania and sterna are totallyabsent from the assemblage.

There is marked variation in the extent ofweathering shown by bones, suggesting differentperiods of predepositional exposure (Figure 9). Thebones that display the greatest evidence forweathering are also the most fragmented. Variation

Taphonomy of Lancefield megafauna 337

• Complete elementsIncomplete elements

Total numberof elements(cranial andpost cranial)

175

150

125

100

75

SO

25o L IBl\1l1l...-_

No evidence forweathering

Flakingonly

Cracking andFlaking

Crackingonly

Weathering features

Figure 9 Proportions of different weathering features on bone elements from Lancefield swamp.

associated with the bone in the assemblage isindicative of high energy fluvial transportation. Thetractional processes, such as saltation and rolling,required to transport larger and heavier clasts overdistance, are also highly destructive to bonematerial. Destruction would have increased inproportion to the distance transported and wouldhave contributed to the abrasion and fragmentationof bone material that had been subaerially exposedprior to transportation.

Groundwater flow is not suggested as thedominant factor in the accumulation of bone andmatrix at Lancefield swamp. Rather, overland orsheet flow, a result of heavy seasonal rainfall in thecatchment surrounding the swamp would havebeen the main transportation mechanism. Weigelt(1989) observed that "Water tumbled pebbles,gravel and sand are characteristics of ... mountainstreams that spread out over the plains. Notuncommonly in these sediments are fossils,transported by water." The occurrence of heavyseasonal rainfall during the late Pleistocene glacialperiod in southeastern Australia is supported byLadd (1976) and Frakes et al. (1987: 16).

Secondly, the assemblage at Lancefield displaysthe characteristics of a lag deposit, which supportsfluvial accumulation. A lag deposit is described byBehrensmeyer (1988), and summarized by Shipman(1993: 56), as " ... coarse deposits of gravel, bonefragments, teeth and other dense particles thatremain in suspension with high current velocities".Smaller elements are selectively winnowed out andtransported away as the larger, heavier elements aredeposited.

Thirdly, the contribution of carnivores andscavengers to the bone assemblage and depositionalbias at Lancefield swamp was not considered in thisstudy, because no signs of carnivore activity wereobserved on the bones collected during the 1991excavations. Evidence for carnivory on bonescollected from the Classic Site at Lancefield swamp

was investigated by Horton and Wright (1981), whofound that only 0.35% of the bones showedpuncture marks or signs of gnawing.

FaunaEvidence for 72 individuals (based on

approximately 3,000 bones) was recovered from theClassic Site alone, and Gillespie et al. (1978)estimated that 10,000 individuals may berepresented by remains in the entire swamp. For allthree Sites, 26 taxa have so far been identified,including 10 megafauna. Site provenance andaggregate minimum numbers of individuals aregiven in Table 3. There has been discussion as towhether Macropus titan and M. giganteus areseparate, or M. titan merely represents the giganticPleistocene form of the modem species (Flannery1981; Van Huet 1994a: 82). For the purpose of thispaper, the species name M. titan is retained toindicate that all remains are from the large formand to avoid confusion in reference to previouswork on Lancefield.

Thylacoleo, then unrecorded from Lancefieldswamp, was suggested by Horton and Wright(1981) as the cause of the cut marks on elementsfrom the Classic Site. Specimens of Thylacoleo (MYP2OO742 and P200852) have since been found in theSouth Site at Lancefield.

DISCUSSION

TaphonomyEvidence from the bones and sediments suggests

that transportation played a major role in thedeposition of the assemblage at the South Site, andprobably the Mayne and Classic Sites, at Lancefieldswamp. Skeletons from animals that died in the areaaround the swamp were subjected to disarticulationand weathering prior to fluvial transportation.Transported bone material was subsequently

338

deposited, along with sediment, in the swamp.Any elements from small animals originally

present were probably either destroyed in transit orwashed away by virtue of their size or density.Larger and heavier elements were deposited in adepression defining the area of the swamp, manyindicating the direction of current flow. Fragileelements from larger species, made even morefragile through exposure, disintegrated and weredeposited as bone fragments; while other elementswere probably removed by saltation, flotation ortractional processes (similar to those observed in avertebrate deposit in Verdigre Quarry, Nebraska byVoorhies 1969a). It was noted for Lancefield thatthe specimens displaying the most weathering werealso those that were highly fragmented. The mostrobust elements in the deposit displayed a variationin abrasion attributable to their shape, compactnessand reaction to abrasive processes.

Gillespie et al. (1978) suggested that deposition ofthe Lancefield swamp sediments, including the bonebed, began about 26,000 BP as a result of a major

S. Van Huet

decrease in spring output leading to a change froman erosive to a depositional flow regime. They notedthat this was consistent with a major hydrologicchange recorded elsewhere in southeastern Australiaat about that date, and confirmed by subsequentwork (e.g., Chappell 1991, and references therein).However, the results of the present study indicatethat the bone bed was deposited under high ratherthan low energy fluvial conditions. The radiocarbondate of 14,950 ± 1240 on charcoal from the bone bedin the South Site, although very imprecise and badlyin need of replication, raises the possibility thatdeposition occurred after, rather than before, the lastglacial maximum. The pollens recorded from theClassic Site (Ladd 1976; Gillespie et al. 1978), showthat the swamp was surrounded by an almosttreeless grassy plain at the time of deposition of thebone bed and overlying mottled clay, consistent withthe dryer than present late glacial climate. Conditionsunder which sheet water flow could have causederosion and transportation of sediments andredeposition of bone, appear more likely to have

Table 3 Fossil vertebrates recorded from Lancefield swamp. Minimum numbers of individuals (MNI) are aggregatefigures of those reported in Gillespie et al. (1978), Munro (1984), and the results of the 1991 field work. X =present; .. =absent; * megafauna. Protemnodon species from the Mayne Site were not differentiated: MNI is forboth species combined from all sites.

Classic Site South Site MayneSiteChannel Bone Bone Bone

Taxon fill bed bed bed MNI

ReptiliaScincidae X 1

AvesDromaius sp. X X 11'OGenyomis sp. X X 4Gallinula mortierii X 1

MammaliaThylacinus cynocephalus X X X 3Sarcophilus sp. X 1'ODiprotodon optatum/australis X X X X 11'OZygomaturus trilobus X X 7Vombatus sp. cf. V. ursinus X X X 3'OThylacoleo camifex X 1Aepyprymnus rufescens X 1Potorous sp. X 1'OPropleopus sp. X 4Macropus dorsalis X 1Macropus rufogriseus X 1'OMacropus titan X X X X 263Cf. Onychogalea X 1Cf. Petrogale X 1Prionotemnus sp. X 1'OProtemnodon anak X X X'OProtemnodon brehus X X X'OProtemnodon X 22Cf. Thylogale X X 2*Procoptodon rapha X 7'OSthenunls occidentalis X X X 7Mastacomys fuscus X X 2Rattus sp. X 1

Taphonomy of Lancefield megafauna

arisen under a regime of increasing precipitation onlightly vegetated soils at the end of the glacial thanunder decreasing rainfall on probably more stablesoils before the last glacial maximum. Post glacialmaximum deposition of the bones implies asubstantial unconformity between the channel filldeposit and the overlying bone bed, which was notobserved by Gillespie et al. (1978). The presence of atleast one major unconformity in the deposit isindicated by the microliths near the base of the blackclay (Gillespie et al. 1978). It is possible that anotherexists lower in the section, where the waterloggedworking conditions of the site make it difficult todetect.

The collection displays a strong bias in favour ofthe representation of larger animals. Because the lifespan of a smaller mammal is significantly shorterthan that of a larger animal, the attrition rate ofsmall animals is naturally much greater, and it canbe expected that a greater number of bones andteeth representing small animals will be foundwithin fossil assemblages. This is not the case atLancefield where evidence for large mammalsgreatly outweighs that for small. As Voorhies(196%) noted "... since there are few moderncommunities in which small mammals, especiallyrodents, do not outnumber large ones, their absenceor rarity in any fossil deposit should be viewed withextreme suspicion". Low representation of smallanimal species provides a strong indication ofselective bias in an accumulation. Lancefield is notan anomalous case. Under-representation of smalleranimals in fossil assemblages is quite common,particularly in collections accumulated underfluviatile conditions (Wolff 1973; Behrensmeyer etal. 1979): in the Amboseli Basin the representationof smaller animals was inversely related to size. Alack of small animal remains suggests a biastowards the selection of bone from larger animals,for whatever reason, and thus is not a fullrepresentation of the contemporary fauna.

DatingEmplacement of the bone bed at Lancefield could

not have occurred before 26,000 BP, the date of theunderlying channel fill (Gillespie et al. 1978), and,as discussed above, could have happenedconsiderably later. The taphonomic evidence forreworking presented in this paper implies that thebones within the bed are older than the bed itself.This has been confirmed by new dates obtainedfrom megafaunal material by Van Huet et al. (1998),which indicate that the age of diprotodontidremains from the South Site falls within the range60,000 to 30,000, with a best average age of about40,000 BP. The primary deposition of bone materialoccurred many thousands of years prior toreworking and redeposition.

Van Huet et al. (1998) discussed the implications

339

of the new dates from Lancefield for the overlap ofhumans and megafauna in Australia. Theyconcluded that while the dates may indicate thatLancefield is a pre-human site, the lengtheningchronology of human occupation of Australiasuggests that some overlap did still occur, althoughfurther sites are needed to support this chronology.Victoria is very poorly endowed with early datesassociated with humans, compared to more aridparts of Australia. By far the oldest is a date fromKeilor of 31600 +1100 -1300 BP (ANU-65; AlIen andHoldaway 1995), but it is probably a minimum datefor the arrival of humans in Victoria. That probablyoccurred at a time beyond the practical limits ofradiocarbon dating (Roberts et al. 1994; Chappell etal. 1996) and, like the extinction of the megafauna,will require the application of multiple datingtechniques to elucidate.

CONCLUSION

On the basis of the very limited fauna, includingonly large species, recorded from the bone bed atLancefield, Gillespie et al. (1978) argued that a'special selective' agent was responsible for thedeaths of the animals, and that the low faunaldiversity was not the biased result of a post mortemsorting process. While the present study does notrule out the possibility of a selective agent at thetime of death, the evidence for fluvialtransportation of skeletal remains that yieldsubstantially older dates than those of theunderlying deposit, shows that post mortem sortingis an equally plausible cause of the biased faunaIcomposition of the assemblage. Both factors mayhave been in operation at different times.

At Lancefield, carcasses and skeletons weresubjected to subaerial weathering. Bones that werehighly weathered were more prone to breakageduring transportation than those less weathered.This resulted in variation in the condition andcompleteness of elements within the assemblage.Fluvial conditions were also responsible forreworking of the deposit, and are the probablecause of the age difference between the faunalmaterial and charcoal from below the bone bed.

ACKNOWLEDGEMENTS

Among the many, thank you to my supervisors,Pat Vickers-Rich and Tom Rich, to MarionAnderson, Mary Waiters and Patricia Komorowerfor proof reading, Charles De Groot for hissearching through MV records, The Lancefield ParkManagement Committee, J. Peter White for hisinterest in my work at the site and in particular,Alex Baynes for his valiant endeavours to teach mehow to write up my work. I thank you all.Photographs were taken by Steve Morton and

340

Adrian Dyer and image manipulation was carriedout by Allan Pursell.

REFERENCESAlien, J. and Holdaway, S. (1995). The contamination of

Pleistocene radiocarbon determinations in Australia.Antiquity 69: 101-112.

Alien, P.A and Collinson, J.D. (1986). Lakes. In Reading,H.G. (ed.), Sedimentary environments and facies, secondedition: 63-94, Blackwell Scientific Publications,Carlton, Victoria.

Behrensmeyer, A.K. (1978). Taphonomic and ecologicinformation from bone weathering. Paleobiology 4:150-162.

Behrensmeyer, AK. (1988). Vertebrate preservation influvial channels. Palaeogeography, Palaeoclimatology,Palaeoecology 63: 183--199.

Behrensmeyer, AK., Western, D. and Dechant Boaz, D.E.(1979). New perspectives in vertebrate paleoecologyfrom a recent bone assemblage. Paleobiology 5: 12-21.

Chappell, J.M.A (1991). Late Quaternary environmentalchanges in eastern and central Australia, and theirclimatic interpretation. Quaternary Science Reviews 10:377-390.

Chappell, J.M.A., Head, M.J. and Magee, J.W. (1996).Beyond the radiocarbon limit in Australianarchaeology and Quaternary research. Antiquity 70:543--552.

Douglas, A.M., Kendrick, G.W. and Merrilees, D.(1966). A fossil bone deposit near Perth, WesternAustralia, interpreted as a carnivore's den afterfeeding tests on living Sarcophilus (Marsupialia,Dasyuridae). Journal of the Royal Society of WesternAustralia 49: 88-90.

Flannery, T.F. (1981). A review of the genus Macropus: 1­255, Unpublished M.Sc. thesis, Department ofEcology and Evolutionary Biology, MonashUniversity, Clayton, Victoria.

Frakes, L.A., McGowran, B. and Bowler, J. (1987).Evolution of Australian environments. In Dyne, G.(ed.), Fauna of Australia, lA, General articles: 1-16,Australian Government Printing Service, Canberra,Australian Capital Territory.

Gillespie, R, Horton, D.R, Ladd, P., Macumber, P.G.,Rich, T.H., Thorne, Rand Wright, RV.5. (1978).Lancefield swamp and the extinction of theAustralian megafauna. Science 200: 1044-1048.

Hobson, E.C (1845). "On fossil bones from Mt. Macedon- Port Phillip" (in a letter dated June, 1845 to Mr RCGunn, Launceston). Tasmanian Journal of NaturalScience 2: 344-347.

Horton, D.R (1976). Lancefield: the problem of proof inbone analysis. The Artefact 1: 129-143.

Horton, D.R. and Samuel, J. (1978). Palaeopathology of afossil macropod population. Australian Journal ofZoology 26: 279-292.

Horton, D.R. and Wright, R.V.5. (1981). Cuts onLancefield bones: carnivorous Thylacoleo, not humans,the cause. Archaeology in Oceania 16: 73--81.

Klein, RG. and Cruz-Uribe, K. (1984). The analysis ofanimal bones from archaeological sites: i-xii, 1-266,University of Chicago Press, Chicago, Ill., U.5.A

S. Van Huet

Ladd, P.G. (1976). Past and present vegetation of theLancefield area, Victoria. The Artefact 1: 113--127.

Marshall, B. and Cosgrove, R (1990). Tasmanian Devil(Sarcophilus harrisii) scat-bone: signature criteria andarchaeological implications. Archaeology in Oceania 25:102-113.

Marshall, L.G. (1989). Bone modification and "The lawsof burial". In Bonnichsen, Rand Sorg, M.H. (eds.),Bone modification: 7-24, Institute of QuaternaryStudies, Orono, Maine, U.5.A

Munro, B. (1984). A study of the Pleistocene fOSSils from theLancefield swamp, Victoria: 1-85, Unpublished 3rd yearproject report, Department of Earth Sciences, MonashUniversity, Clayton, Victoria.

Orchiston, D.W., Miller, R.N. and Glenie, RC (1977). Ahistory of nineteenth century investigations at theLancefield megafaunal site. The Artefact 2: 105-122.

Pettijohn, F.J., Potter, P.E. and Seiver, R (1972). Sand andsandstone: i-xvi, 1-618, Springer-Verlag, New York,N.Y., U.5.A

Roberts, R.G., Jones, R and Smith, M.A (1994). Beyondthe radiocarbon barrier in Australian prehistory.Antiquity 68: 611-616.

Shipman, P. (1993). Life history of a fossil: 1-222, HarvardUniversity Press, Cambridge, Mass., U.5.A

Taylor, N. (1863). Notes explanatory of the geology of thedistrict comprised in Quarter sheet 5 S.E. and S.W. and6 N.E. and NW. In Selwyn, ARC, Reports and papersrelative to the mining and geological survey of Victoria: 6-9,Government Printers, Melbourne, Victoria.

Van Huet, S. (1993). A brief history of palaeontologicalinvestigation at the Lancefield megafaunal site. TheVictorian Naturalist 110: 154-159.

Van Huet, S. (1994a). The taphonomy of a late Quaternarysite, Lancefield swamp, Victoria: 1-151, UnpublishedM.5c. thesis, Department of Earth Sciences, MonashUniversity, Clayton, Victoria.

Van Huet, S. (l994b). The Lancefield megafauna site,Victoria. Abstract of paper presented at CAVEPS1993. Records of the South Australian Museum 27: 229.

Van Huet, S., Griin, R, Murray-Wallace, CV., Redvers­Newton, N. and White, J.P. (1998). Age of theLancefield megafauna: a reappraisal. AustralianArchaeology No. 46: 5-11.

Voorhies, M.R. (1969a). Taphonomy and populationdynamics of an early Pliocene vertebrate fauna, KnoxCounty, Nebraska. Contributions to Geology, Universityof Wyoming Special Paper No. 1: 1-69.

Voorhies, M.R. (1969b). Sampling difficulties inreconstructing late Tertiary mammalian communities.Proceedings of the North American PaleontologicalConvention, 454-468.

Weigelt, J. (1989). Recent vertebrate carcasses and theirpalaeobiological implications: i-vii, 1-187, University ofChicago Press, Chicago, Ill., U.5.A

Wolff, RG. (1973). Hydrodynamic sorting and ecology ofa Pleistocene mammalian assemblage from California,USA. Palaeogeography, Palaeoclimatology, Palaeoecology13: 91-101.

Manuscript received 31 December 1997; accepted 8 February1999.