determining the gait of miocene, pliocene, and pleistocene

Foss Rec 24 151ndash169 2021httpsdoiorg105194fr-24-151-2021copy Author(s) 2021 This work is distributed underthe Creative Commons Attribution 40 License

Determining the gait of Miocene Pliocene andPleistocene horses from fossilized trackwaysAlan VincelettePretheology Department St Johnrsquos Seminary Camarillo CA 93021 USA

Correspondence Alan Vincelette (avincelettestjohnsemedu)

Received 19 November 2020 ndash Revised 11 May 2021 ndash Accepted 11 May 2021 ndash Published 10 June 2021

Abstract Much work has been done on the study of ver-tebrate gaits over the past several decades and efforts un-dertaken to apply this to fossil tracks especially dinosaursand mammals such as cats dogs camels and horses Thiswork seeks to expand upon such studies and in particular tostudy footprints laid down in sand by modern horses and ap-ply such studies to determine the gaits of fossil horse track-ways It thus builds upon the work of Renders (1984a b)and Kienapfel et al (2014) and suggests additional measure-ments that can be taken on horse footprints In this studythe footprints left in the sand by 15 horses of various breedswith various gaits were videotaped photographed describedand measured in order to determine characteristics useful indistinguishing gaits These results were then applied to twonew sets of fossil footprints those of the middle Miocenemerychippine horse Scaphohippus intermontanus that I per-sonally examined and measured and those from the latePleistocene horse Equus conversidens previously illustratedand described in the literature (McNeil et al 2007) The lat-ter horse exhibits a fast gallop of around 94 ms but it isthe former whose footprints are quite unique The quantita-tive and visual features of these prints are suggestive of amedium-fast gait involving apparent ldquoundersteppingrdquo of di-agonal couplets and hind feet that overlap the centerline Thegait that most closely matches the footprints of Scaphohippusis the ldquoartificialrdquo gait of a slow rack or toumllt or pace around19 ms though an atypical trot of a horse with major con-formation issues or which is weaving (swaying) from side toside is a less likely possibility This intimates along with theearlier study of Renders (1984a b) who found the artificialgait of the running walk displayed by Pliocene hipparioninehorses that ancient horses possessed a much greater varietyof gaits than modern horses and that over time they lost theseabilities with the exception of certain gaited breeds

1 Introduction

Among horses one of the most diverse sets of gaits of anyanimal species can be observed Some of these gaits are stan-dardly classified as ldquonaturalrdquo as they occur in nearly all horsebreeds and usually do not have to be explicitly taught to thehorses There are four such natural gaits the walk trot can-ter and gallop in increasing order of speed (Grogan 1951Hildebrand 1965 1977 Gray 1968 Prost 1970 Leach andDagg 1983 Barrey 1999 2013b Starke et al 2009 Harris2016 pp 55ndash93 Serra Braganccedila 2020 2021) Other horsegaits are termed ldquoartificialrdquo ldquoacquiredrdquo ldquoamblingrdquo or ldquoeasyrdquoas they tend to be restricted to specialized breeds and mayrequire extensive training of the horse to bring them out yetare quite smooth for the rider These artificial gaits includethe paso fino running walk fox trot toumllt and pace (Nicode-mus and Clayton 2003 Ziegler 2005 Robilliard et al 2007Harris 2016 pp 95ndash122) It should be noted however thatthe word ldquoartificialrdquo is here somewhat of a misnomer as manyof these gaits appear spontaneously in different horse bloodlines and may also be exhibited in foals of multiple horsebreeds before being lost or untrained

Horse gaits can also be distinguished by whether they aresymmetrical that is the legs mirror each other on both sidesof the horsersquos body are coordinated and so involve ipsilat-eral or contralateral limbs moving together (ie lateral ordiagonal coordination) as opposed to involving limbs thatmove individually or in a dissociated manner as well as interms of number of beats speed stride or cycle length over-tracking (overstepping) duty factor suspension phases andsupport structures along with other characteristics such asadvanced placement Many studies have been devoted to de-scribing the nature of such gaits I collate and reproduce thekey findings of these studies below (see also Tables 1 and 2)

Published by Copernicus Publications on behalf of the Museum fuumlr Naturkunde Berlin

152 A Vincelette Determining the gait of Miocene Pliocene and Pleistocene horses

11 Symmetrical laterally dissociated gaits

Symmetrical laterally dissociated gaits are those wherein thelimbs chiefly operate independently of each other begin-ning with a sequence of limbs moving one after the otheron one side of the horse followed by a similar sequence onthe horsersquos other side (hence such gaits have sometimes beendescribed as bipedal or square) This almost always involvesa footfall pattern of left hind (LH) left front (LF) right hind(RH) and right front (RF) Such gaits include the walk pasofino and running walk of horses

The walk is the natural slow-speed gait of the horse It oc-curs at a typical speed of 14ndash18 ms and with a cycle (stride)length of 157ndash193 cm Because it involves laterally dissoci-ated and isochronous limb movements it is a four-beat gaitIt is also a non-suspended gait as there is at least one footon the ground at all times In fact in the walk there are typi-cally two or three limbs supporting the horsersquos weight at alltimes or more particularly a triangular support structure fol-lowed by alternating lateral and diagonal bases of supportThis makes the walk quite stable and easy on the horse Moretechnically the walk has a duty factor around 06 as each limbis on the ground for around 60 of the stride and a stride fre-quency of around 08ndash11 strides per second depending uponthe speed The walk can occur at slow (12ndash13 ms) medium(13ndash22 ms) or fast (22ndash30 ms) rates Horses can alsoengage in a collected walk with short quick and elevatedmarching steps around 150ndash160 cm in length or an extendedwalk with longer and less frequent steps around 180ndash200 cmin length In slow and collected walks the three-legged sup-port structure dominates and the hind feet tend to make con-tact with the ground behind (undertracking) or overlapping(capping) the ipsilateral front feet In medium-speed (work-ing) walks the hind feet typically contact the ground just infront of the ipsilateral front feet Finally in extended and fastwalks the hind hooves often overtrack (overstep) the ipsilat-eral front hooves The walk will normally transition to thetrot at high speeds (Clayton 1995 Nicodemus and Slater2009 Weishaupt et al 2010 Soleacute et al 2013)

There also exist some ldquoartificialrdquo laterally dissociated gaitsfound in specialized horse breeds These artificial gaits likethe standard walk are isochronal four-beat symmetrical gaitsand display the same footfall sequence of left hind left frontright hind and right front but are modified in various waysmost often so that the gait is smoother for the rider

The paso fino of Columbian Paso horses is a slow (09ndash13 ms) walking gait but one that is highly collected withhigh and quick steps (stride frequency around 26 stridess)one possessing a duty factor of 055 In the paso fino thehind feet will usually undertrack the ipsilateral front feetby a considerable distance and so contralateral feet comedown near each other forming diagonal couplets As it isslow and collected there are always at least three feet on theground for increased support and a comfortable gait that can

be sustained for a long time (Nicodemus and Clayton 2003Novoa-Bravo et al 2018)

The running walk (slow amble paso llano) is the artificialmedium to fast gait of Tennessee Walking Spotted Saddleand Peruvian Paso horses The running walk can occur atmedium (ca 27 ms) to fast (ca 38ndash41 ms) speeds It pos-sesses an extended cycle length wherein the hind feet over-track the ipsilateral front feet by several inches forming lat-eral couplets at medium speeds four individual imprints atfast speeds and diagonal couplets at very fast speeds as theoverstep exceeds 25 of the cycle length This results in thelimbs being on the ground 40 to 50 of the stride cycle(ie a duty factor of 04 to 05) and the body being occa-sionally supported by only one limb as opposed to the con-tinual two or three limb support in the standard walk Still asthe support structure in the running walk typically involvesan ipsilateral or diagonal two-limb support structure alongwith a brief tripedal support period it is a smooth gait for therider (Renders 1984a b Nicodemus et al 2002) TennesseeWalking and Missouri Foxtrotting horses can also exhibit aslower variation in the running walk the flat walk again withextended strides and overtracking but at a speed of only 2ndash3 ms

12 Symmetrical diagonally coupled gaits

The trot is the natural medium to fast gait of the horse whichis an isochronal diagonally coupled two-beat gait whereincontralateral front and hind limbs move in a coordinatedmanner lifting off the ground in sync swinging togetherand striking the ground nearly at the same time (the hind-foot sometimes contacts the ground just before the front footor vice versa) forming lateral couplets The two-beat foot-fall sequence of the trot is hence LH+RFminusRH+LF Thisresults in two suspended phases in the stride wherein all fourfeet are off the ground (for 9 of stride duration) The trothas a typical duty factor of 035ndash045 and a frequency of 15ndash20 stridess Like the walk the standard trot can occur at dif-ferent speeds slow (jog) at speeds of 25ndash36 ms with mod-erate undertracking medium at speeds of 36ndash54 ms withcapping of hoofs or fast at speeds of 54ndash90 ms with over-tracking of front feet by hind feet The cycle (stride) length ofthe trot is typically around 200ndash450 cm The trot may also becollected or extended The collected trot employs short high-stepping and quick strides and often undertracks as in Hack-ney and Morgan horses and can have a duty factor up to 06The extended trot is a fast trot with long strides increasedsuspension phases and a great deal of overtracking (Stre-itlein and Preuschoft 1987 Clayton 1994 Holmstroumlm et al1994 Leleu et al 2004 Weishaupt et al 2010 Hobbs et al2016 Walker et al 2017) The Standardbred horse can per-form an extremely fast flying trot at speeds of 100ndash142 msa stride frequency of 25 stridess and a cycle length of 500ndash600 cm The flying-trot beats are asynchronous (irregular)with an abaxial lateral offset of the hind limbs and turns

Foss Rec 24 151ndash169 2021 httpsdoiorg105194fr-24-151-2021

A Vincelette Determining the gait of Miocene Pliocene and Pleistocene horses 153

into a four-beat gait (Jordan 1910 Drevemo et al 1980ab) The trot can rapidly cover a fair amount of ground yetit gives the horse a solid diagonal base of support betweensuspended phases thus providing lots of balance for unevensurfaces The horse moreover is capable of maintaining thetrot for a long time The trot is less comfortable for the riderhowever as the horse bounces up and down

There are a few ldquoartificialrdquo diagonally coupled gaits Thepassage (prancing trot) is a slow collected elevated trotfound in American Saddlebred Andalusian and Lippizanhorses as well as in and Dutch German and Swedish Warm-bloods and indeed is considered a demonstratable natural gaitin the German riding tradition It is a two-beat gait but in thepassage the stride becomes slightly asynchronous with thehindfoot touching down just before the diagonal front footresulting in a brief period of single-digit support between thediagonal phases and extended periods of floating suspensionThe duty factor of the passage is around 04 The passagehas a smoother ride than the trot but is much slower (12ndash18 ms) and tiring for the horse These same horse breedscan also perform the piaffe which is an even more collectedelevated and slower gait with a very short stride and thehorse almost appears to trot in place The piaffe has a dutyfactor between 045ndash05 There is no suspension phase at allin the piaffe and the support structure varies between two di-agonal to three limbs on the ground (Weishaupt et al 2009Clayton and Hobbs 2019)

The fox trot (pasitrote) is another diagonally coupled gaitfound in the Missouri Foxtrotter and the Kentucky Moun-tain horse It is a medium-slow speed trot involving fourhighly asynchronous (irregular) beats short quick steps (16ndash23 stridess in the fox trot up to 27ndash29 in the trocha) diag-onal couplets and undertracking to slight overtracking Thespeed of the fox trot is around 3ndash4 ms with strides around200 cm long The fox trot is the trot-based equivalent of theslow gait or broken pace That is to say the fox trot is a bro-ken trot wherein diagonal limb pairs lift off the ground atthe same time and swing forward together but the front footstrikes the ground slightly before the contralateral hind foot(by 10 ndash15 of stride duration) resulting in a slight de-lay between the striking of ipsilateral feet and a footfall pat-tern of LHminus (LFminusRH)minusRF For this reason the fox trot issometimes described as a horse walking with its front legswhile trotting with its hind legs In the fox trot there are twoalternating lateral and diagonal feet on the ground for supportfor much of the stride (82 of stride) and sometimes threefeet (18 of stride) with a duty factor of 05 and no aerialphase It is smooth for the rider and stable and easy for thehorse although there is a slight rocking back-and-forth mo-tion The Carolina Marsh Tacky the Columbian Paso Finoand the Mangalarga Marchador can also perform a slow col-lected fox trot (the trocha or marcha batida) wherein the sup-port structure varies between two diagonal limbs to three oreven four limbs on the ground at once (Clayton and Brad-

bury 1995 Nicodemus and Clayton 2003 Nicodemus andSlater 2009)

13 Symmetrical laterally coupled gaits

Not surprisingly all of the laterally coupled gaits are ldquoartifi-cialrdquo as they involve the horse balancing its weight on oneside while the ipsilateral limbs on the other side move inconjunction The slow gait (stepping pace paso corto so-breandando marcha picada) is a medium-slow-speed gait(20ndash35 ms) found in American Saddlebred Paso and Man-galarga Marchador horses The slow gait has a typical strideduration of 06ndash05 s but the marcha picada variation foundin the Mangalarga Marchador has a larger stride duration of09 s It has four beats along with a collected quickened andoften heightened stride with a fair amount of undertrackingIn the slow gait the ipsilateral hind and fore feet start thegait at the same time but the hind foot contacts the groundslightly before the ipsilateral front foot This causes the gaitto become asynchronous with a slight delay between the sec-ond and third beats as the lateral leg pairs strike the groundcloser together than the diagonal leg pairs The slow gaithence has a footfall pattern of (LHminusLF)minus (RHminusRF) Theslow gait is thus a sort of broken pace with the lateral feettaking off together but landing separately in order to elimi-nate the suspension phases which is why it is also called thestepping pace In the slow gait accordingly there is only abrief period where there is just one foot on the ground andnormally two and sometimes three feet make contact mak-ing it a smooth gait to ride one that can cover ground morequickly than the walk but without the vertical motion of thetrot or the rolling motion of the pace It is also similar to aslow rack but with the slight delay between the second andthird beats Though not overly tiring for the horse and ca-pable of long distances the slow gait is hard on the horsersquosjoints (Gonccedilalves Fonseca et al 2018)

The rack (amble toumllt paso largo huschano trippel re-vaal) is a slow to medium-fast artificial gait found in Amer-ican Saddlebred and Standardbred horses Rocky Mountainand Florida Cracker horses Paso horses the Icelandic horseand Indian Marwari Kathiawari and Sindhi horses The rackor toumllt has the same general footfall pattern as the walk(LHminusLF)minus (RHminusRF) with equal intervals between eachof the four beats and a duty factor of 035ndash055 but it hashigher and quicker strides (15ndash22 stridess) and more ex-tended steps with cycle lengths around 150ndash300 cm longThe rack is a sort of broken pace wherein the hind and fronthooves lift off the ground almost simultaneously but the hindhoof comes back down a little before the ipsilateral fronthoof At slower speeds of 3ndash6 ms (walking rack pleasurerack stepping rack) the rack has the same support structureas the walk with alternating lateral and diagonal limb pairsfollowed by three limbs on the ground As there is only amoderate amount of overstepping ipsilateral couplets tend tobe present At fast speeds of 6ndash9 ms there are periods when

httpsdoiorg105194fr-24-151-2021 Foss Rec 24 151ndash169 2021


there is just one foot on the ground (hence the alternativenames of (single-foot coon rack or speed rack) followed byalternating lateral and diagonal support phases with two feetalong with lots of overtracking This results in diagonal cou-plets forming as contralateral limbs land close together Therack is comfortable for riders but it is quite tiring for horsesand cannot be maintained for long periods of time (Zips etal 2001 Nicodemus and Clayton 2003 Pecha et al 2011Boehart et al 2013 Waldern et al 2015 Gunnarsson et al2017 Stefaacutensdoacutettir et al 2021)

The fastest laterally coupled gait is the pace (huachanoSchweinepass fast amble) which is a two-beat gait found inStandardbred Peruvian Paso and Icelandic horses The paceis even faster than the trot as it involves diagonal couplets andless interference of limbs and is capable of speeds of 90ndash160 ms though it most often occurs at around 5ndash8 ms Inthe pace though the lateral limbs lift off in unison and swingforward together the hind foot often makes contact just be-fore the front foot with each limb remaining on the groundfor 28 ndash35 of the gait The pace also has a very highstride frequency of 18ndash27 stridessecond and its length istypically between 300ndash600 cm The footfall sequence in thepace is LH+LFminusRH+RF and it has a support structureof opposing ipsilateral pairs The pace can be performed in aslow and collected manner (pacing walk) where undertrack-ing often occurs and one forelimb may contact the groundbefore the contralateral limb lifts off resulting in brief diag-onal support phases alternating with lateral support phasesand the suspended phases being reduced or eliminated Ice-landic horses display a very fast variant called the flying pace(skeieth) which can achieve speeds of up to 130 ms for shortdurations with a large amount of overtracking (over 25 of the cycle length) and couplets that are now lateral onesThe pace is not as stable and balanced as the trot but is eas-ier on the horse and more comfortable for the rider albeitproducing a side-to-side rolling motion as well as a fore andaft see-sawing motion (Wilson et al 1988a Boehart et al2013 Stefaacutensdoacutettir et al 2021)

14 Asymmetrical gaits

Horses possess two main asymmetrical gaits with limbmovements that do not mirror each other on the two sides ofthe horsersquos body and so what can be described as a leadingfoot These are also fast three- to four-beat gaits typicallywith only a single suspension phase and naturally occur-ring in horses At medium-fast speeds horses often engage inthe three-beat canter (Canterbury gallop) wherein diagonallimbs impact together for the second beat The canter is par-ticularly prominent in the American Saddlebred TennesseeWalking and Western Pleasure horses Dutch German andSwedish Warmbloods Icelandic horses and the MangalargaMarchador The canter typically occurs at a medium-fastspeed (4ndash8 ms) during which the horse moves forward ina slightly diagonal direction The canter has a cycle fre-

quency of 15ndash25 cycles per second a duty factor of 035and a cycle length of around 200ndash400 cm If the horse canterswith a left lead then the sequence of the three beats is righthind the diagonal left hind and right front feet spring andland together (or on occasion the hind foot lands just beforethe front foot) and finally the left-leading forelimb hits theground forming a footfall pattern of RHminusLH+RFminusLF Ifthe horse canters with a right lead then the sequence of thethree beats is left hind then the diagonal pair of the righthind and left front move and touch down together and fi-nally the right forelimb makes contact so it has a footfallpattern of LHminusRH+LFminusRF In the standard canter thesupport structure cycles between one and two diagonal limbson the ground followed by an aerial phase In the slow col-lected canter (ldquoslow galloprdquo) of the Columbian Paso horsethe horse takes short and elevated steps and at least one limbis on the ground at all times with the hindfoot undertrackingthe ipsilateral front foot In the medium-speed collected can-ter (or lope in western riding) with a speed around 18 msa cycle frequency of 14 cycless and a cycle length around130 cm there are occasions where all three limbs are on theground at once but there is also an aerial phase The canter isless tiring for the horse than the gallop and can provide gooddiagonal or triangular support on rough terrain but it is notas fast as the trot or gallop (Deuel and Park 1990 Loitsch1993 Clayton 1993 1994 Back et al 1997 Nicodemusand Clayton 2001 Nicodemus and Booker 2007 Splan andHunter 2004)

At fast speeds the horse naturally transitions to a transversegallop a fast four-beat gait wherein each limb only makescontact with the ground for 20 ndash30 of the cycle durationThe gallop involves either a left- or right-leading foot In theleft-lead gallop the right hind foot moves first followed bythe left hind and right front legs moving forward in diago-nal unison but with the hind limb hitting the ground slightlybefore the front limb ending with the independent ldquoleadingrdquoleft front foot contacting the ground Hence the footfall pat-tern of the left-lead gallop is RHminus (LHminusRF)minusLF In theright-lead version the left hind limb moves first then the righthind and left front diagonal pair moving forward togetherwith the hind limb hitting the ground slightly before the fore-limb and finally the ldquoleadingrdquo right front leg lands makingthe footfall pattern LHminus (RHminusLF)minusRF There is a supportsequence of one (54 of the cycle duration) or two contralat-eral limbs (27 of the cycle duration) for much of the gallopcycle as well as an aerial phase (19 ndash28 of the cycle dura-tion) The standard gallop reaches speeds between 9ndash12 ms(Bertram and Gutmann 2009) The cycle length of such agallop is quite long varying from 300ndash500 cm and the fre-quency ranges from 20ndash29 cycless The fast extended gal-lop (or run) of Thoroughbreds and Quarter horses can reachspeeds of 10ndash18 ms with a cycle frequency of 23ndash30 cy-cless a stance duration approaching 01 and a cycle lengthof 440ndash700 cm Though the gallop can attain high speeds itis fatiguing for the horse and can only be kept up for 3 to 5 km



(Deuel and Lawrence 1986 Leach et al 1987 Seder andVickery 2003a b Witte et al 2006 Takahashi et al 2007Parsons et al 2008 Morrice-West et al 2020) Horses havealso been observed to perform a rotary gallop for short burstsespecially during the initial acceleration phase of a race be-fore switching to a transverse gallop The rotary gallop isa very fast four-beat left- or right-lead double-suspensiongait wherein the limbs alternate between an extended sus-pension and a collected suspension causing the pattern oflimb impacts to switch diagonally or transversely from righthind followed by left hind to left front followed by right frontie with a footfall sequence of LHminusRHminusRFminusLF (Hilde-brand 1980 Seder and Vickery 2003a b Bertram and Gut-mann 2009 Biancardi and Minetti 2012)

2 Methods and materials

A 15mtimes 5m straight section of track was raked in a sandyhorse arena to allow footprints to distinctly show up whenhorses treaded over it Fifteen horses of different breeds andsizes (see Table S1 in the Supplement) were ridden or walkedover the prepared trackway in various gaits Breeds studiedincluded Andalusian Arabian Quarter horses as well as Sad-dlebreds Tennessee Walkers and Thoroughbreds

Sketches were made and photographs taken of the horsefootprint trackways (along with videos of the most recentlystudied horses as indicated in the footnote to Table S1) in or-der to identify footfall patterns and for rough measurementsof speed and distance traversed Horizontal measurementsalong the plane of motion were then taken with a ruler or tapemeasure between the footprints of the gait in accordance withfairly standard protocols such as measuring the cycle (stride)length the distance between steps or between front and hindfeet pairings (which I have called the intercouplet distance)and the overtrack or undertrack between ipsilateral or diag-onal feet pairings (see Leach et al 1984 Renders 1984ab Thompson et al 2007) In addition three lateral measure-ments were taken the distance ipsilateral (or diagonal) feetpairs were out of parallel alignment (what I have called thelateral offset) the distance between contralateral feet impres-sions (what I have called the interior straddle in contrast withthe standard straddle measurement between outer edges ofthe hoofs of contralateral impressions or the diagonal widthmeasurement between contralateral mid-hooves as in Leachet al 1984 fig 5) and the distance between the center ofeach ipsilateral or diagonal pairs of feet (which I have calledthe cross-measure as it often occurs at an angle to the centerplane of motion if there is any lateral offset of the coupletssee Fig 1 below)

Because access to easy-gaited horses in the western UnitedStates is limited and especially so due to travel and visita-tion restrictions due to Covid-19 I supplemented the previ-ous data with data culled from videos of horses displayingvarious gaits I have kept these data segregated as they are

Figure 1 Measurements taken on horse tracks CL cycle lengthICD intercouplet distance (ie distance between couplets ornearby pairs of prints) OT overtrack IS interior straddle (ie be-tween inner edges of contralateral limbs) CM cross-measure(ie distance from the center of one hoof impression to anotherwithin a couplet) LO lateral offset (ie lateral distance betweenedges of footprints in a couplet)

less accurate than the above I have also made use of the datapresent in other studies on horse gaits in particular those ofKienapfel et al (2014) or Renders (1984a b) In the datatables given below and in the text the superscripts V forvideos K for Kienapfel or R for Renders are attached toa horse number or a measured value to indicate its sourceie 18V 012R and 22K

Finally the average for each of the measurements wascalculated for the distinct gaits and key ratios deter-mined including such ratios as cycle (stride) length heightovertrack intercouplet distance and cross-measure cyclelength (see Tables 3 and 4)

Next sketches were made and measurements taken of twosets of fossil horse footprints (see Tables 5 and 6) The formeris a track likely made by the merychippine horse Scapho-hippus intermontanus1 around 145 Ma in middle Miocene(middle Barstovian Ba2 Barstow Formation) lacustrine sedi-ments of the Mud Hills deposit (Greer Quarry) near BarstowCalifornia This horse laid down a set of four imprints ona track 61 cm long The uppermost impression is partialonly (reconstructed as a whole print in Fig 5 with a dot-ted line indicating where the break occurs) Sarjeant andReynolds (1999 pp 15ndash17) individually described mea-sured and photographed these prints (ichnospecies Hip-pipeda araiochelata) and I too have examined measuredand traced these footprints and molds of them made in situ

1This species which was formerly placed in the genusMerychippus albeit with some hesitancy by Pajak andVincelette (1991) has been reassigned more recently to Scapho-hippus intermontanus (Pagnac 2006)



Table 1 Descriptive features found in the major gaits of the horse

Gait Footfall sequence Beats Synchronicity Symmetry Limb supportstructures

Couplets Suspendedphases

Walk LHminusLFminusRHminusRF 4 Isochronous Laterallydissociated

2ndash3 Lateral 0

Runningwalk

LHminusLFminusRHminusRF 4 Isochronous Laterallydissociated

1ndash3 Lateral to noneto diagonal

0

Paso fino LHminusLFminusRHminusRF 4 Isochronous Laterallydissociated

3 Lateral 0

Fox trotand trocha

LHminus (LFminusRH)minusRF 4 Asynchronous Diagonallycoupled

2ndash3 Diagonal tonone

0

Trot LH+RFminusRH+LF 2 Isochronous Diagonallycoupled

0ndash2 Lateral 2

Passage LH+RFminusRH+LF 4 Asynchronous Diagonallycoupled

1ndash2 Lateral 2

Slow gait (LHminusLF)minus (RHminusRF) 4 Asynchronous Laterallycoupled

2ndash3 (to 1) Diagonal 0

Toumllt orrack

(LHminusLF)minus (RHminusRF) 4 Isochronous Laterallycoupled

1ndash2 (to 3) None todiagonal

0

Pace LH+LFminusRH+RF 2 Isochronous Laterallycoupled

0ndash2 Diagonal tolateral

2

Canter LHminusRH+LFminusRF orRHminusLH+RFminusLF

3 Isochronous Asymmetric 0ndash3 Singlediagonal pair

1

Gallop LHminus (RHminusLF)minusRF orRHminus (LHminusRF)minusLF

4(2+ 2)

Isochronous Asymmetric 0ndash3 None 1

at the San Bernardino County Museum in additional waysfollowing the protocol given above

The latter is a set of footprints made by the late Pleis-tocene horse Equus conversidens in aeolian sands and siltsnear a river at the Wallyrsquos Beach deposit near Cardstonin Alberta Canada The trackway consists of five imprintslaid down across 401 cm of sand some 11 000 years agoI however here rely upon the descriptions (ichnospeciesHippipeda cardstoni) to-scale drawings and measurementsgiven in McNeil et al (2007 pp 215ndash218) and have not ex-amined these footprints in person

Finally the measurements key ratios and patterns of thefootprints made by the living and fossil horses were com-pared in order to see if the gait and speed of the fossil horsesthat left the prints could be determined

3 Results

31 Observable and measurable differences betweenfootprint patterns within modern horse gaits

The walk because it is a slower gait lays down hoof printsin ipsilateral couplets (2ndash2) that are close together and typ-ically in parallel alignment alternating between the left andthe right side of the centerline (see Figs 2 3a) The stridesof the walk are short and about the same distance as theheight of the horse at the withers averaging 1471 and1770 cm in a slow and fast walk (or an average ratio of cyclelength height of 095 in a slow walk and 110 in a fast walk)with a distance between couplets (intercouplet distance) av-eraging 527 cm in a slow walk and 572 cm in a fast walkor around 34 and 36 of the horse height and 36 and32 of the cycle length respectively (see Tables S2 and S3in the Supplement) In slower walks the hind hoof impres-sion often overlaps or caps the impression made by the ip-silateral front hoof and there may even be an undertrack ofup to 6 cm separating the two impressions (hence the over-track cycle length ratio averaged minus007 in the slow walk)In faster walks there is moderate overtracking of the front



Table 2 Quantitative measurements of the main gaits of the horse

Gait Speed(ms)

Cycle length(cm)

Strideor cycleduration(s)

Strideor cyclefrequency(stridess)

Duty factor(percent ofgait in stancephase)

Suspenseduration(percent ofgait in aerialphase)

Lateraladvancedplacement()

Diagonaladvancedplacement()

Walk 08ndash22 150ndash200 18ndash09 08ndash11 045ndash07 0ndash05 02ndash03 06ndash07

Running walk 27ndash38 200ndash250 08ndash07 04ndash05 05ndash06 0 02ndash03 03ndash06

Paso fino 09ndash13 ca 170ndash230 04 22ndash29 055 0 02ndash03 05ndash06

Fox trotand trocha

30ndash40 ca 200 06ndash04 16ndash29 02ndash05 0 02 01

Trot 20ndash86 200ndash265 08ndash05 16ndash25 035ndash045 10ndash20 04ndash06 02ndash06

Passage 12ndash18 ca 200ndash220 05ndash04 09ndash11 04 ca 5ndash7 ca 05ndash06 ca 04ndash05

Slow gait andmarchapicada

20ndash35 ca 250 06ndash05(09)

ca 25ndash29 ca 02ndash04 ca 0ndash01 01ndash02 ca 04ndash05

Rack or toumllt 12ndash106 170ndash300 06ndash04 18ndash24 02ndash04 0ndash02 02ndash04 02ndash04

Pace 50ndash160 450ndash630 05ndash04 18ndash24 03ndash045 5ndash15 01ndash03 04ndash05

Canter 40ndash98 190ndash460 06ndash04 16ndash21 02ndash05 3ndash5 02ndash04 01

Gallop 79ndash180 300ndash720 05ndash03 20ndash30 02ndash03 15ndash30 0 ca 01

hoof by the hind hoof by an average distance of 30 cm (or anovertrack 002 the length of the stride) Because in the walkipsilateral feet tend to line up in parallel (average lateral off-set of 17 cm in the slow and 31 cm in the fast walk) andclose together (average interior straddle of 36 cm in the slowand 14 cm in the fast walk) the cross-measure between thehoofprints in a couplet is small averaging 91 and 176 cm inthe slow and fast walk (or a cross-measure cycle length ra-tio of 006 and 010 in the slow and fast walk respectively)The paso fino has footprints and cycle lengths that resemblea very slow walk

The running walk also lays down prints in ipsilateral cou-plets (2ndash2) but in a considerably faster gait with a longercycle length (averaging 135 times the horse height) Con-sequently there is considerable overtracking on average248 cm (12 of the cycle length) the intercouplet distanceshrinks somewhat to an average of 426 cm (20 of the cyclelength) and the overtrack distance between ipsilateral hoofimpressions begins to close in on the distance between cou-plets (the ratio of the overtrack intercouplet distance being58 ) Generally speaking in the running walk as in the stan-dard walk the ipsilateral prints will line up in a parallel lineand again just to the left or right of the centerline However atvery fast speeds the trackway of the running walk begins tolook like four individual prints spaced roughly equally apartrather than ipsilateral couplets (consult Fig 2 and Table S4in the Supplement)

Figure 2 Illustrations of tracks left in the sand by various horsegaits (a) Fast walk (b) running walk (c) fast trot (d) fast rack(e) slow pace (f) left-lead canter (g) right-lead gallop LH left hindprint RH right hind print LF left front print RF right front print



The trot again lays down tracks in ipsilateral couplets withthe footprints of the ipsilateral pair occurring close togetherbut not as close as in the standard walk (see Figs 2 3b)Because the trot is a faster gait the cycle length is long av-eraging 1939 and 2651 cm in a slow and fast trot (form-ing around a 123 ratio in relation to horse height in a slowtrot and 171 in a fast one) and the intercouplet distance islarge measuring 710 and 1030 cm in the slow and fast trot(see Tables S5 and S6 in the Supplement) As a result the in-tercouplet distance cycle length ratio is just slightly largerthan in the walk (037 and 039) but considerably larger incomparison to horse height (045 and 066) In slower trotsthe hind feet usually undertrack and fall short of the ipsi-lateral front feet by an average of 32 cm (minus006 ratio forovertrack cycle length) but in fast trots there can be a fairlylarge overtrack of up to 5 cm (but with an average value ofminus0002 of the overtrack cycle length ratio as the stride isquite long) The ipsilateral pairs in the trot are also close tothe centerline with the interior straddle averaging 28 and23 cm in the slow and fast trot but there is a greater tendencyfor ipsilateral feet to be out of parallel alignment (resultingin an average lateral offset of 30 and 50 cm for the slowand fast trot) As a result there is an average cross-measureof 152 and 139 cm in a slow and fast trot (or 8 and 5 of the cycle length respectively) The passage displays foot-prints resembling a very slow trot (see Fig 4a)

The medium to fast rack or toumllt has a quite different ap-pearance than the standard walk or trot For in the mediumto fast rack (as well as in the pace) the couplets are formedby contralateral feet landing near each other typically withldquoundertrackingrdquo of the rear print behind its contralateral frontpartner and so form pairs that point away from the centerlinein alternating directions (see Figs 2 4c) This gives rise to aldquowave-shapedrdquo trackway of footprints The rack of the singleindividual studied here featured a cycle length of 3089 cm(199 times the size of the horse height) and a large intercou-plet distance as with the fast trot of 1099 cm (71 the sizeof the horse height and 36 the size of the cycle length)The rack here featured an undertrack of contralateral feet of114 cm (or 009 the length of the long stride) There weretwo key distinguishing features of the rack (as well as thepace) The first is that as the rack features contralateral cou-plets there is a large lateral offset averaging 51 cm and aneven larger cross-measure of 283 cm (018 the length of thestride) This is even the case in spite of the second key featureof the rack (or pace) a tendency for a very narrow track andcontralateral hoof prints that laterally overlap (interior strad-dle of minus66 cm) The footprint pattern and measurements ofthe pace are similar to those of the rack however they couldonly be studied here indirectly via video In the pace in con-trast to the rack the hind feet tend to overtrack the contralat-eral front feet as the gait occurs at high speeds (see Tables S7and S8 in the Supplement for measurements of the rack (toumllt)and pace) The related slow gait visually resembled a slowrack in having a wave-like shape to the footprint pattern as

the couplets are comprised of alternating pairs of diagonalfeet wherein the hind hoof undertracks the contralateral fronthoof but possessed a shorter cycle length and intercoupletdistance (see Fig 4b) The standard fox trot though not stud-ied in depth here also lays down footprints similar to a slowrack as even though the limbs are diagonally coordinated atits slow speed diagonal limbs strike the ground near eachother forming diagonal couplets

The canter is visually unmistakable as it lays down a trackwith a 1ndash1ndash2 (or technically 1ndash2ndash1) sequence of prints typi-cally with two medium-length steps of nearly equal distanceafter the couplet followed by a step of longer or shorter dis-tance depending upon the speed (see Figs 2 3c) In terms ofmeasurables the canter displays a long stride that averaged2521 cm (160 times the height of the horse) Contralateralfeet usually fall near the centerline (average interior straddleof 18 cm) but as the couplet is formed by the footfalls ofcontralateral pairs it is quite extensive here as in the rackaveraging 59 cm and forming a couplet angling away fromthe centerline to the left or right depending upon the leadThe horse also tends to move in an overall diagonal in thecanter (see Table S9 in the Supplement)

The gallop is also easy to recognize as it consists of fourindividually separated prints with long distances betweenthem (see Figs 2 3d) The first two prints tend to be closertogether (284 cm apart on average) followed by three longersteps which are on average 735 cm long This gives rise toa long stride of around 3070 cm or almost double the sizeof the horse height (191 on average) in just a restrained gal-lop In the gallop the contralateral footprints fell farther awayfrom the centerline than in the other gaits with an interiorstraddle averaging 92 cm (see Table S10 in the Supplement)

32 Description and measurements of fossil horsetracks

In addition to studies undertaken on the modern horse tracksnoted above illustrations and measurements were also takenof the two sets of fossil horse tracks described above

The foot impressions left by the middle Miocenemerychippine horse Scaphohippus intermontanus around145 Ma are unusual in appearance (see Fig 5 below) Fourimprints occur in two couplets that overlap the centerline (in-terior straddle of minus10 cm) and alternate in pointing outwardto the left and then to the right The uppermost impression ispartial only as noted earlier The three complete foot impres-sions measure 52 50 and 47 cm in length and the crackedimpression 17 cm The width of the three complete printsis 35 cm while the width of the incomplete impression is37 cm These measurements were taken on the mold of theprints in order to capture the distances between the printsThe prints themselves are slightly larger having been mea-sured as 62 56 and 62 cm in length and 38 cm in width(Sarjeant and Reynolds 1999 p 15) and shown to be equiv-alent in size to adult hoof bones assigned to the same species



Figure 3 Photographs of four common horse gaits (a) Fast walk (Horse 10a) (b) fast trot (Horse 10b) (c) right-lead canter (Horse 9)(d) right-lead gallop (Horse 8) LH left hind print RH right hind print LF left front print RF right front print

Table 3 Average values and range of key measurements from various gaits in modern horses

Gait Calculatedspeed(ms)

Cyclelength(cm)

Intercouplet orinterstep distance(cm)

Overtrack orundertrack(cm)

Interiorstraddle(cm)

Left andright lateraloffset (cm)

Left andright cross-measure(cm)

Slow walk 180 1471 527 minus102 (09) 36 13 21 92 90Fast walk 233 1770 572 30 14 29 33 165 187Running walk 324 2127 426 248 13 na naSlow trot 280 1939 710 minus125 (32) 28 44 15 152 152Fast trot 479 2651 1030 minus037 23 53 46 139 139Slow gait 450 2565 831 minus267 (114) minus25 51 51 273 273Rack 614 3086 1099 minus279 minus66 51 51 283 283Canter 432 2521 644 32 18 59 181Gallop 586 3070 622 na 92 na na

na not applicable

found nearby Because front feet of horses are often shorterand wider than hind feet (Stachurska et al 2008 Reynolds2006) this suggests that there is considerable undertrackingdisplayed here namely ca minus109 cm (53ndash58 cm betweenprints within a couplet) orminus011 the size of the cycle lengthThere is also a large amount of lateral displacement 18 cmin the lower couplet and 13 cm in the upper couplet (for anaverage of 16 cm or 002 the size of the cycle length) and asizable average cross-measure of around 111 cm or 011 thesize of the cycle length

The fossilized track made by the late Pleistocene horseEquus conversidens (McNeil et al 2007 fig 16) consists

of five hoof imprints 105 cm in length and width The dis-tance between the steps based upon the scale drawing were100 709 564 and 873 cm proceeding from start to end ofthe cycle The interior straddle varied from 36ndash127 cm

To determine the other key ratios related to horse foot-prints the size of the horse at the withers needs to be deter-mined Studies have shown correlations between adult horsesize and hoof size (Stachurska et al 2011) third metacarpallength (Onar et al 2018) and cranial length along withthird metapodial length (Chroacuteszcz et al 2014) As the re-mains of the horses studied here involve footprint impres-sions which from my observations are nearly identical to



Figure 4 Photographs of some ldquoartificialrdquo horse gaits (a) Passage (Horse 10) (b) slow gait (Horse 15) (c) fast rack (Horse 15) LH lefthind print RH right hind print LF left front print RF right front print

horse hoof size in slower gaits utilizing the correlations ofhoof size with height at the withers is an important startingpoint Stachurska et al (2011) found the height at the withersin Arabian and Half-Arabian horses to be 1283ndash1316 timesthe size of the front hoof length This would yield a heightof ca 728 cm for Scaphohippus intermontanus which had afront hoof 56 cm long and a height of 1364 cm for Equusconversidens which had a front hoof 105 cm long In addi-tion if we use the cranial length of 315 cm for a Scaphohip-pus intermontanus skull of ca 149 Ma (American Museumof Natural History AMNH FM 87301) and multiply it bythe factor of 27 suggested by Chroacuteszcz et al (2014 p 145)we get a height of 851 cm

That being said studies have suggested that metacarpalsize is a more reliable predictor of overall horse size than ei-ther cranial or phalanx length (Alberdi et al 1995 Chroacuteszcz

et al 2014) Hence it is important to also utilize the studyof Onar et al (2018 p 163) who found that the height ofmodern horses averaged 566 times the size of the metacarpallength Postcranial remains of Scaphohippus intermontanusare relatively rare but Merriam (1919 pp 502ndash503) as-signs one complete metacarpal found in nearby strata to thespecies It measured 165 cm (the metatarsal was 181 cmlong) This would yield a height of 934 cm Equus conversi-dens has a metacarpal that averaged 228 cm long (Harris andPorter 1980 p 50) which would yield a height of 1290 cm

In what follows I estimate the height of the fossil horses byaveraging these two values ie the estimation of size basedupon hoof length and metacarpal length This yields a heightof 792 cm for Scaphohippus intermontanus and 1328 cm forEquus conversidens



Table 4 Key ratios of modern horse gaits

Gait Cyclelength

height

Intercoupletdistance heightand intercoupletdistance cyclelength

Overtrack (undertrack)

intercouplet distance andovertrack (undertrack)

cycle length

Average lateral offset intercouplet distanceand lateral offset cyclelength

Average cross-measure

intercouplet distance andaverage cross-measure

cycle length

Slow walk 095087K

034 and 036029 and 033K

minus021 and minus0070 and 0K

003 and 0010007 and 0009K

019 and 006008 and 009K

Fast walk 110119K

036 and 032036 and 030K

005 and 002019 and 006K

005 and 0020 and 0K

031 and 010007 and 006K

Runningwalk

135 027 and 020 058 and 012na and ca 014R

na na

Slow trot 123140K

045 and 037(056 and 040K)

minus018 and minus006minus005 and minus002K

005 and 002002 and 001K

022 and 008006 and 004K

Fast trot 171174K

066 and 039066 and 038K


005 and 0020006 and 0003K

014 and 005013 and 008K

Slow gait 166 052 and 032 minus033 and minus010 003 and 002 018 and 011

Rack or toumllt 199172V

118K

071 and 036056 and 032V

027 and 023K

minus025 (010) and minus009minus039 (023) and minus012V

minus068 and minus016K

005 and 002010 and 003V

002 and 002K

026 and 009040 and 013V

019 and 016K

Pace 181V

256K063 and 034V

077 and 030K029 and 009V

021 and 006K013 and 004V

004 and 001K034 and 011V

016 and 006K

Canter 160153K

041 and 026039 and 026K

003 and 0010006 and 0002K

011 and 002004 and 002K

033 and 007009 and 006K

Gallop 191175K

039 and 020(033 and 019K)

na na na

Finally I wanted to include footprints of the hippario-nine2 horse Eurygnathohippus previously studied by Ren-ders (1984a b) Renders (1984a p 179) records a hooflength of 65 cm which would yield a height of 844 cmper the above formula of Stachurska Hooijer (1975 p 33)records the length of a skull (BK II pit 6 (upper Bed II)nos 2845ndash2846) of 260 cm which would yield a horseheight of 702 cm Bernor et al (2005 pp 152 and 157 AL155ndash6) and Van der Made (2014 fig 8) record the size of thethird metacarpals of Hipparion (Eurygnathohippus) as 262and 240 cm This would give a horse height of 1421 cm ac-cording to the formula above If we average the value fromthe hoof and metacarpal lengths we get an estimated heightof 1059 cm

2Some of the African hipparionine horses including the speciesstudied here have of late been reassigned to Eurygnathohippus ha-sumense (Hooijer 1987 Armour-Chelu and Bernor 2011 Bernoret al 2005 2010 Van der Made 2014)

4 Discussion

Scientific inquiry into the gaits of extinct vertebrates hasincreased exponentially over the past few decades Exten-sive investigations have been undertaken on the gaits of di-nosaurs (Alexander 1976 Thulborn 1982 1989 Mazzettaand Blanco 2001 Henderson 2006 Stevens et al 2016Bordy et al 2020) camels (Alf 1966 Webb 1972 Sarjeantand Reynolds 1999 McNeil et al 2007 Thompson et al2007 Cabral-Perdomo et al 2018) and horses (Renders1984a b Kienapfel et al 2014) among other vertebratesSuch studies have compared cycle (stride) length speed andfootprint patterns of living species with fossilized trackwaysin order to elucidate the gaits of extinct vertebrate species

This paper expands upon such work and examines foot-print patterns of several living horse breeds in order to in-crease the database of gaits in living analogs In particularextensive measurements have been taken on various facets ofhorse footprints including cycle (stride) length overtrack-ing distance between couplets (intercouplet distance) dis-tance between contralateral feet (interior straddle) and thealignment of prints in a couplet (lateral offset and cross-



Table 5 Measurements of fossil horse tracks

Species Geologicalage

Hoof imprintlength (cm)

Cycle length(cm)

Distance betweencouplets or steps(cm)


Left and right lateraloffsetcross-measure(cm)

Equus conversidens ca 11 000 ka ca 105 ca 3566 564 873100 709

na na

Eurygnathohippushasumense a

ca 37 Ma ca 65 ca 1320 ca 12 18 ca 36 36 ca 52 (21) 53 (27)

Eurygnathohippushasumense b

ca 37 Ma ca 65 ca 1395 ca 27 35 ca 24 30 ca 53 (27) 53 (33)

Scaphohippusintermontanus

ca 145 Ma ca 47ndash52(53ndash58)

ca 983 333 ca minus108 to110(58ndash60)

18 (110)13 (ca 111)

Table 6 Key ratios of fossil horse tracks Speed calculated from formula in Alexander (1976) estimated speed (ms)= 1565 (ms2)times stride(cycle) length (m)167

times height (m)minus117

Species Stride

heightSpeed(ms)

Intercouplet (step)distance height andintercouplet (step)distance cyclelength

Overtrack

intercoupletdistance andovertrack cyclelength



height and averagecross-measure cyclelength

Equus conversidens 269 94 059 and 022 na ca 82 na


117 22 032 and 027 240 and 027 ca 0 021 and 018


123 24 027 and 022 087 and 019 ca 15 026 and 022


118 19 042 and 034 minus033 and minus011 ca minus10 014 and 011

measure) in order to distinguish various horse gaits It thenapplies the results to two sets of isolated extensive andclearly defined fossil horse tracks one from the merychip-pine horse Scaphohippus intermontanus in middle Miocenestrata from the Mud Hills deposits of California and an-other from Equus conversidens in late Pleistocene rocks fromWallyrsquos Beach deposits in Alberta Canada in order to deter-mine the gaits exhibited Finally a reevaluation of the tracksof the hipparionine horse Eurygnathohippus from Pliocenerocks at site G of the upper Laetoli Beds in Tanzania (Ren-ders 1984a b) is undertaken

The largest and most recent horse the late PleistoceneEquus exhibited a left-lead gallop at a fairly rapid speed of94 ms Such a gait is evident as the footprint pattern showsfour separate prints nearly equidistant apart and spaced outover a long stride The high ratio of stride height of 269 isindeed indicative of a very rapid gallop It is hard to knowwhy this Pleistocene horse was running at such a fast speedperhaps it was being chased by predators migrating or justout for fun

Intriguingly the data suggest that Scaphohippus intermon-tanus was displaying the ldquoartificial gaitrdquo of a slow rack ortoumllt (or slow pace or slow gait) of around 19 ms The ratioof the stride length height of 118 suggests a medium-speedgait such as a slow trot or rack as do the values of 042 and034 for the intercouplet distance height ratio and minus033and minus011 for the overtrack intercouplet distance and over-track cycle length ratios Three factors however point tothis gait being a rack or toumllt (or slow gait fox trot or slowpace) as opposed to a trot In the first place the footprintsdisplay a considerable negative interior straddle of aroundminus10 cm A negative interior straddle was most often seenoccurring in diagonally coupled gaits as there is room forthe limbs to come close together without interference In factnegative interior straddles seem relatively rare in the trotthough they can occur on occasion (I observed one such oc-currence in horse 3 ofminus51 cm) usually due to conformationissues or a horse that is weaving (swaying) from side to siderather than moving in a straight line see Figs S1 and S2 inthe Supplement and Kienapfel 2014 figs 6 and 7) Second



Figure 5 Illustrations of fossil horse tracks (a) Merychippinehorse tracks (Scaphohippus intermontanus) Dotted line in fore-most Scaphohippus print indicates where impression is broken off(b) Hipparionine horse tracks (Eurygnathohippus hasumense) afterRenders (1984a b fig 2) (c) Equus conversidens tracks after Mc-Neil et al (2007 fig 16) LH left hind print RH right hind printLF left front print RF right front print

in spite of the negative interior straddle there are fairly largecross-measure height and cross-measure cycle length ra-tios found in the tracks of Scaphohippus here namely val-ues of 014 and 011 Now the average values of cross-measure height and cross-measure cycle length ratios are022 and 08 in a slow trot versus 018 and 011 in a slowrack This again is suggestive of a rack being exhibited byScaphohippus however the occasional slow trot can havea cross-measure cycle length ratio of 012 (as happenedonce in horse 9) Finally and perhaps most importantly theScaphohippus footprints suggest an ldquoundertrackingrdquo of di-agonal couplets as the nearby print pairs are laterally offsetwhile forming a line that points away from the centerline ofthe stride or in other words forming a wave-shaped trackway(see Figs 5 and 6) An occasional trot wherein the horse haspoor conformation and is dishing or plaiting or where it isweaving (swaying) from side to side can also form a trackwith a wave shape (as happened in horse 3 see Fig 6 be-low and Figs S1 and S2 in the Supplement) but individualhoof impressions will usually point towards or away fromthe centerline and not line up perpendicular to the center-line as is the case in the fossil footprints studied here So the

fact that here the hoof impressions all individually orient ina forward-pointing manner but that the hind feet overlap andalternate between being to the left and then to the right of thefront foot strongly suggests a gait with diagonal limbs land-ing near as found in the rack and the pace (as well as the slowgait and fox trot) Indeed in a rack with ldquoundertrackingrdquo (un-derstepping) the hind feet (here at the rear of the couplets)tend to align with each other as they transition to an innertrack and straddle the centerline whereas in a wave-shapedtrot with undertracking it is most often the innermost printsformed by the ipsilateral feet that align in the two couplets(see Fig 4b see also Kienapfel 2004 figs 5 6 7) Suchalignment of the hind feet is found within the Scaphohip-pus prints Hence if we superimpose the Scaphohippus printsover rack and wave-shaped trot trackways the fit is betterfor the rack than the wave-shaped trot (see Fig 6) All inall then the gait that best fits the measurements and patternsdisplayed by the Scaphohippus prints is a slow to mediumrack with undertracking of contralateral feet though a trot isnot outside the realm of possibility It is unfortunate that onlyfour impressions were preserved as a few more impressionscould have provided additional evidence as to which gait wasoccurring in Scaphohippus

If Scaphohippus was indeed engaging in the ldquoartificialrdquogait of a rack or toumllt or a pace then it seems earlier horseswere quite ldquogaitedrdquo and had laterally coupled gaits naturallyavailable to them Renders (1984a b) has already shown thatEurygnathohippus horses could stride in a running walk gaitwhich is not a natural gait of horses There could be severalexplanations for why this horse was engaging in a rack orslow pace A pacing gait is sometimes seen in animals thatare juveniles weak or fatigued Hence some foals pace be-fore learning how to trot Still the horse tracks of Scaphohip-pus match the size of adult coffin bones and so they do notseem to be that of an overly young horse Such alternativegaits could have been useful to early horses as they allowhorses to travel at a similar or faster speed than in the trotbut with less expenditure of energy Such gaits though not asstable as the trot may additionally have been useful in allow-ing fast speeds over varied or uneven terrain for they allowthe horse to switch between a lateral and diagonal limb sup-port structure and keep one foot on the ground at all timesThis is one reason the toumllt is useful in Iceland with its var-ied volcanic and glacial outcroppings and why the pace isbeneficial in camels on the sand dunes Another possibility isthat Scaphohippus was an early grazing horse (Feranec andPagnac 2017) and it may have quickly developed long legsbut with a relatively short body and hence found the rack orslow pace more efficient or a way to avoid limb interferenceas in camels or dogs

Renders (1984a p 179) in fact has already used com-parisons between living horse footprints and those displayedby two adult hipparionine horses (Eurygnathohippus ha-sumense) at site G of the upper Laetoli Beds in Tanzaniato argue for their traveling in the ldquoartificialrdquo gait of a run-



Figure 6 (a) Scaphohippus tracks scaled up rotated and superimposed over rack trackway of Horse 15 to produce best possible fit(b) Scaphohippus tracks scaled up rotated reversed and superimposed over wave-shaped trot trackway of Horse 3 to produce best pos-sible fit Note better overall alignment with rack than with trot how the fossil back prints line up nearly in parallel as in the rack as opposedto the trot and that in the wave-shaped trot displayed here the modern horse front prints are pointing away from centerline but not in thefossil prints which occurs when an irregular-shaped trot is formed

ning walk of 18 and 22 ms I concur with her assessmentthough I have recalculated the speeds of the two gaits aseven faster at 22 and 24 ms based upon newer estimatesof horse height I should also note that Renders measures thecycle (stride) length as the distance between the first fourfootprints only and so did not include the distance to thereturn of the initial foot to the ground as is normally doneIf we use the latter more typical measurement of the cyclelength then the overtracks of the hipparionine fossil horseswere 019 and 027 times the distance of the cycle length(as opposed to 027 and 031 Renders 1984a p 180) Thisovertrack length is still considerable and illustrates that atvery fast running walks the overstepping can be so large asto form diagonal instead of lateral couplets (as is seen in Ren-ders 1984a fig 2)

The possibility that ancient horses could rack or toumllt orpace (as well as display the running walk) is an interestingfind in light of recent studies in horse genetics indicatingthat modern horses possess a so-called ldquogait-keeper generdquo(DMRT3) that limits the gaits and speeds of which they arecapable (Andersson et al 2012 Kristjansson et al 2014Promerovaacute et al 2014 Jaumlderkvist Fegraeus et al 20152017 Regatieri et al 2016) In gaited horses the DMRT3gene has a mutation that results in a shorter and less func-tional protein unit The normal DMRT3 gene yields a pro-tein that is active in the spines of mammals and helps to co-

ordinate their limb movements between front and hind andbetween the opposite sides of the body The mutated formof the gene makes it harder for young animals to coordi-nate their hind limbs and transition to a gallop Hence horsebreeds with the mutation such as Standardbred Paso Finoand Icelandic horses can more easily learn to pace or engagein some other ldquoartificialrdquo gait The mutated DMRT3 gene haseven been tracked back to a presumable first appearance inninth-century England (Wutke 2016) As wild horses alsopossess the normal DMRT3 gene the fact that earlier horsescould rack or toumllt suggests there may be more to the storygenetically and perhaps horses developed genes that limitedtheir gait possibilities but allowed for the easier developmentof the three standard gaits of walk trot and gallop as thiswas beneficial to their survival In any case more recent stud-ies have suggested a more complicated genetical picture forhorse gaits as other genes than DMRT3 seem to be involvedin such gaits as the fox trot and whether or not a horse hasa tendency to trot or pace (Gonccedilalves Fonseca et al 2017Staiger et al 2017 Novoa-Bravo et al 2018 McCoy et al2019)

Other fossil horse hoof prints that have been examineddiagrammed or photographed are not fully gaitable by myestimation They often occur as single impressions or cou-plets in which case reconstructing the exact gait is not possi-ble For example there is an early Miocene (ca 165 Ma)



horse footprint couplet present in the Barstow Formationof Prosperity Canyon western Calico Mountains California(Reynolds 2006 fig 1) The hoof impressions are 295 cmin length with an overtrack roughly equal to the size of thehoof or around 25 cm with a slight lateral offset betweenthe pair of impressions This is hence a large overtrack andsuggests a faster gait such as a trot pace or canter Howeverlacking other foot impressions it is not possible to eliminateany of these possibilities or even if it is a fast walk

On other occasions there are multiple fossilized horsehoof prints but the opposite problem of an overabundanceof wealth is they occur as trample grounds wherein multi-ple individuals step near and on top of each otherrsquos tracksmaking it hard to determine which impressions belong tothe same individual Such is the case with the late Hem-ingfordian (He 2) tracks of the Muddy Creek Formation inMoapa Nevada where footprints 32 cm long formed around17 Ma (Reynolds 2006 fig 2) It is also the case with thePliocene lacustrine ldquoBarnyardrdquo site at Copper Canyon inDeath Valley California of early Blancan sediments (Bl 1)of around 425 Ma Here likely Hipparion or Neohipparionset down multiple prints 92ndash108 cm long (Santucci et al2014 fig 7 Nyborg et al 2012 fig 7f) Similar are thelate Pliocene (Blancan 3) Dinohippus [] hoof imprints mea-suring 62 cm that formed around 2 Ma in fluvialndashalluvialsediments of the Ocotillo Formation VallecitondashFish CreekBasin in Anza-Borrego Desert State Park California (Re-meika 2006) and Pleistocene (late Irvingtonian Ir 2) tracks10ndash125 cm long formed around 1 Ma in Lake Tacoma sed-iments near Shoshone Death Valley California (Reynolds1999) As it stands it is very hard to distinguish individualtrackways from the available photographs and illustrationsMore fieldwork in these areas may be able to isolate foot-print pathways made by a single individual and hence allowthe more exact determination of a horse gait

5 Conclusion

In closing let it be noted that determining the gaits of fossilhorses from their tracks can be difficult as trackways may betrampled upon by other animals and so isolating individualsequences of prints can be quite challenging In addition thepreserved portion of trackways are usually minimal and typ-ically there are not enough footprints preserved to make de-termination of a gait possible Finally it may be difficult todistinguish front and hind footprints due to minimal differ-ences between them in the horse species or due to the qual-ity of the imprint on account of the substrate and the exactspecies and size of the horse making the track may not bewell known

Still as has long been noted gaits involve unique patternsof limb coordination and footfalls and these are often re-flected in observable patterns in footprints made (see Fig 1below as well as Jordan 1910 p 274 Smith 1912 p 635

Renders 1984a b Kienapfel et al 2014) Moreover by at-tending to overall stride length distances between pairs ofprints (intercouplet distance) distances of overtracking andarrangements between closely impacting pairs of feet (lat-eral offset and cross-measure) determination of a horsersquos gaitfrom footprint measurements is often possible

Quite extraordinarily in applying the above methodologyin order to determine the gaits displayed by fossil horses (inconjunction with the studies of Renders 1984a b and Kien-apfel et al 2014) it appears that Miocene to Pliocene horsesdid not just walk and presumably trot and gallop but couldalso engage in the so-called ldquoartificialrdquo gaits of the rack ortoumllt and running walk All of this suggests that early horseswere clearly ldquogaitedrdquo and capable of a wide range of gaitsperhaps helping them outmaneuver prey on different terrainsand also effectively migrate from place to place This widerange of gaits available to earlier horses seems to have beenreduced in modern breeds through selection and breedingthus reducing the pool of available gaits to the four naturalgaits (walk trot canter gallop) found in most horse breeds

At any rate it is hoped that this study in combination withthose of others will help resolve gaits exhibited by fossilizedhorse prints in the future Further work would be beneficialon living horses vis-agrave-vis measuring the exact speed of thegait via videos or speed guns and correlating this with gaitvariations including detailed measurements of interior strad-dle and degree of hoof rotation away from the centerlineor nearest impression as well as how many parallel tracksof prints occur in any particular gait and their arrangementMuch more work on the kinematics and characteristics ofthe slow gait rack pace and fox trot in the moving horseand associated footprints needs to be done at slow and fastspeeds In addition studies of hoofprints made by unshodhorses would be desirable as these would mimic the natu-ral state of extinct horse species Finally the study of Kien-apfel et al (2014) in conjunction with my calculations forestimated speed using the formula in Alexander (1976) sug-gests that Alexanderrsquos formula works well for faster horsegaits but overestimates the speed of slower horse gaits andthis is a line of research that could be pursued Such an inves-tigation could also look at the relation between overall bodyproportions such as the ratio of the limb length trunk lengthand how this affects gait characteristics in horses camelstapirs and rhinos at different ages

Sample availability The Scaphohippus intermontanus footprintsand molds are housed at the San Bernardino County MuseumRedlands California location SBCM 1-130-394 holotype SBCML1816-3436 There is also a third metatarsal of Scaphohippus in-termontanus around 107 cm long housed at the San BernardinoCounty Museum (L1585-56) but from considerably older DavisRanch strata Cajon Valley Formation Unit 3 (ca 16ndash17 Ma) TheScaphohippus intermontanus skull is housed at the American Mu-seum of Natural History in New York (AMNH FM 87301) The



Equus conversidens footprints are housed at the Royal Alberta Mu-seum Edmonton Alberta specimen DhPg-8 3840-3843 The Eu-rygnathohippus hasumense footprints are still located at Site G inLaetoli Tanzania

Supplement The supplement related to this article is available on-line at httpsdoiorg105194fr-24-151-2021-supplement

Competing interests The author declares that there is no conflict ofinterest

Acknowledgements The author wishes to thank Margaret ResketoAnne Gunther Derk Adams Jennifer Gardener Jessica Farrell Vic-toria Chaidez Aretha Crout Nani Barnes Flora Jean Weiss Cyn-thia Binder and Kimberly Anderson who aided in studies on thefootfall patterns of living horses as equestrians or research assis-tants

Review statement This paper was edited by Rene Hoffmann andreviewed by Holger Preuschoft and one anonymous referee

References

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Alexander R M Estimates of speeds of dinosaurs Nature 261129ndash130 httpsdoiorg101038261129a0 1976

Alf R M Mammal trackways from the Barstow Formation BullS Calif Acad Sci 65 258ndash264 1966

Andersson L S Lahrhammar M Memic F Wootz H Schwo-chow D Rubin C-J Patra K Arnason T Wellbring LHjaumllm G Imsland F Petersen J L McCue M E Mick-elson J R Cothran G Ahituv N Roepstorff L MikkoS Vallstedt A Lindgren G Andersson L and Kullan-der K Mutations in DMRT3 affect locomotion in horsesand spinal circuit function in mice Nature 488 642ndash646httpsdoiorg101038nature11399 2012

Armour-Chelu M and Bernor R L Equidae in Paleontologyand Geology of Laetoli Human Evolution in Context Volume2 Fossil Hominins and the Associated Fauna edited by Harri-son T Springer 295ndash326 Dordrecht the Netherlands 2011

Back W Schamhardt H C and Barneveld A Kine-matic comparison of the leading and trailing fore- andhindlimbs at the canter Equine Vet J Sup 23 80ndash83httpsdoiorg101111j2042-33061997tb05060x 1997

Barrey E Methods applications and limitations of gait analysis inhorses Vet J 157 7ndash22 httpsdoiorg101053tvjl199802971999

Barrey E Gaits and interlimb coordination in Equine locomo-tion edited by Beck W and Clayton H M Saunders 85ndash97Philadelphia Pennsylvania 2013b

Bernor R L Haile-Selasse Y and Scott R S A contribution tothe evolutionary history of Ethiopian hipparionine horses (Mam-malia Equidae) Morphometric evidence from the postcranialskeleton Geodiversitas 27 133ndash158 2005

Bernor R L Armour-Chelu M Gilbert W Kaiser T M andSchulz-Kornas E Equidae in Cenozoic Mammals of AfricaUniversity of California Press 685ndash721 2010

Bertram J E A and Gutmann A Motions of the run-ning horse and cheetah revisited Fundamental mechanicsof the transverse and rotary gallop Interface 6 549ndash559httpsdoiorg101098rsif20080328 2009

Biancardi C M and Minetti A E Biomechanical determinants oftransverse and rotary gallop in cursorial mammals J Exp Biol215 4144ndash4156 httpsdoiorg101242jeb073031 2012

Boehart S Marquis H Falaturi P and Carstanjen B Influenceof palmarly added weights on locomotor parameters of the toumllt ofIcelandic Horse and comparison with corresponding data of theflying pace Pferdeheilkunde 29 628ndash632 2013

Bordy E M Rampersadh A Abrahams M Lockley MG and Head H V Tracking the PliensbachianndashToarcianKaroo firewalkers Trackways of quadruped and biped di-nosaurs and mammaliaforms PLoS One 15 e0226847httpsdoiorg101371journalpone0226847 2020

Cabral-Perdomo M A Bravo-Cuevas V M Perez-PerezA and Garcia-Cabrera N Descripcioacuten de las huellas decameacutelidos y feacutelidos de la localidad Pie de Vaca CenozoicoTardiacuteo de Puebla centro de Meacutexico y algunas considera-ciones paleobioloacutegicas B Soc Geol Mex 70 397ndash416httpsdoiorg1018268bsgm2018v70n2a9 2018

Chroacuteszcz A Janeczek M Pasicka E and Kleckowska-NawrotJ Height at the withers estimation in the horses based on theinternal dimension of cranial cavity Folia Morphol 73 143ndash148 httpsdoiorg105603FM20140021 2014

Clayton H M The extended canter A comparison of some kine-matic variables in horses trained for dressage and for racing ActaAnat 146 183ndash187 httpsdoiorg101159000147443 1993

Clayton H M Comparison of the stride kinematics of thecollected working medium and extended trot in horsesEquine Vet J 26 230ndash234 httpsdoiorg101111j2042-33061994tb04375x 1994

Clayton H M Comparison of the stride kinematics of the col-lected medium and extended walks in horses Am J Vet Res56 849ndash852 1995

Clayton H M and Bradbury J W Temporal characteristics of thefox trot a symmetrical equine gait Appl Anim Behav Sci 42153ndash159 httpsdoiorg1010160168-1591(94)00539-Q 1995

Clayton H M and Hobbs S J Review of biomechani-cal gait classification with reference to collected trot pas-sage and piaffe in dressage horses Animals 9 763httpsdoiorg103390ani9100763 2019

Deuel N R and Lawrence L M Gallop velocity and limb con-tact variables of quarter horses J Equine Vet Sci 6 143ndash147httpsdoiorg101016S0737-0806(86)80064-8 1986

Deuel N R and Park J-J Canter lead change kinematics of supe-rior Olympic dressage horses J Equine Vet Sci 10 287ndash298httpsdoiorg101016S0737-0806(06)80013-4 1990

Drevemo S Dalin G Fredricson I and Hjerteacuten G Equine lo-comotion 1 The analysis of linear and temporal stride char-



acteristics of trotting Standardbreds Equine Vet J 12 60ndash65httpsdoiorg101111j2042-33061980tb02310x 1980a

Drevemo S Fredricson I Dalin G and Bjoumlrne K Equinelocomotion 2 The analysis of coordination betweenlimbs of trotting Standardbreds Equine Vet J 12 66ndash70httpsdoiorg101111j2042-33061980tb02311x 1980b

Feranec R S and Pagnac D C Hypsodonty horses and thespread of C4 grasses during the middle Miocene in Southern Cal-ifornia Evol Ecol Res 18 201ndash223 2017

Gonccedilalves Fonseca M De Camargo Ferraz G Lage J LuisPereira G and Abdallah Curic R A genome-wide asso-ciation study reveals differences in the genetic mechanismof control of the two gait patterns of the Brazilian Man-galarga Marchador Breed J Equine Vet Sci 53 64ndash67httpsdoiorg101016jjevs201601015 2017

Gonccedilalves Fonseca M Silvatti A and Lage J Kinematics ofmarcha picada of Mangalarga Marchador horses with AA andAC genotypes of DMRT3 Comp Exerc Physiol 14 S51 2018

Gray J Animal locomotion Weidenfield and Nicolson London265ndash281 1968

Grogan J W The gaits of horses J Am Vet Med Assoc 118112ndash117 1951

Gunnarsson V Stefaacutensdoacutettir G J Jansson A and RoepstorffL The effect of rider weight and additional weight in Icelandichorses in toumllt Part II Stride parameters responses Animal 111567ndash1572 httpsdoiorg101017S1751731117000568 2017

Harris A H and Porter L S W Late Pleistocene Horses ofDry Cave Eddy County New Mexico J Mammal 61 46ndash65httpsdoiorg1023071379956 1980

Harris S E Horse gaits balance and movement Turner NashvilleTennessee 2016

Henderson D M Burly gaits Centers of mass stabil-ity and the trackways of sauropod dinosaurs J Ver-tebr Paleontol 26 907ndash921 httpsdoiorg1016710272-4634(2006)26[907BGCOMS]20CO2 2006

Hildebrand M Symmetrical gaits of horses Science 150 701ndash708 httpsdoiorg101126science1503697701 1965

Hildebrand M Analysis of asymmetrical gaits J Mammal 58131ndash156 httpsdoiorg1023071379571 1977

Hildebrand M The adaptive significance of tetrapod gait selectionAm Zool 20 255ndash267 1980

Hobbs S J Bertram J E and Clayton H M An explorationof the influence of diagonal dissociation and moderate changesin speed on locomotor parameters in trotting horses PeerJ 4e2190 httpsdoiorg107717peerj2190 2016

Holmstroumlm M Fredricson I and Drevemo S Biokinematicanalysis of the Swedish Warmblood riding horse at trotEquine Vet J 26 235ndash240 httpsdoiorg101111j2042-33061994tb04376x 1994

Hooijer D A Miocene to Pleistocene Hipparions of Kenya Tan-zania and Ethiopia Zool Verh 142 3ndash80 1975

Hooijer D A Hipparions of the Laetoli beds Tanzania in LaetoliA Pliocene Site in Northern Tanzania edited by Leakey M Dand Harris J M Clarendon Press 301ndash312 1987

Jaumlderkvist Fegraeus K Freyja Imsland N H Aacuternason T Ander-sson L Andersson L S and Lindgrena G The importanceof the DMRT3 ldquoGait keeperrdquo mutation on riding traits and gaitsin Standardbred and Icelandic horses Livest Sci 176 33ndash39httpsdoiorg101016jlivsci201503025 2015

Jaumlderkvist Fegraeus K Hirschberg I Aacuternason Andersson LVelie B D Andersson L S and Lindgren G To pace or notto pace a pilot study of four- and five-gaited Icelandic horseshomozygous for the DMRT3 ldquoGait Keeperrdquo mutation AnimGenet 48 694ndash697 httpsdoiorg101111age12610 2017

Jordan R The gait of the American trotter and pacer William RJenkins New York 1910

Kienapfel K Laumlbe S and Preuschoft H Do tracks yield reliableinformation on gaits ndash Part 1 The case of horses Foss Rec 1759ndash67 httpsdoiorg105194fr-17-59-2014 2014

Kristjansson T Bjornsdottir S Sigurdsson A Andersson L SLindgren G Helyar S J Klonowski A M and Arnason TThe effect of the ldquogait keeperrdquo mutation in the DMRT3 gene ongaiting ability in Icelandic horses J Anim Breed Genet 131415ndash425 httpsdoiorg101111jbg12112 2014

Leach D H and Dagg A I A review of research on equinelocomotion and biomechanics Equine Vet J 15 93ndash102httpsdoiorg101111j2042-33061983tb01726x 1983

Leach D H Ormrod K and Clayton H Standardised ter-minology for description and analysis of equine locomotionEquine Vet J 16 522ndash528 httpsdoiorg101111j2042-33061984tb02007x 1984

Leach D H Sprigings E J and Laverty W H Multivariatestatistical analysis of stride-timing measurements of nonfatiguedracing Thoroughbreds Am J Vet Res 48 880ndash888 1987

Leleu C Cotrel C and Barrey E Effect of age on locomotion ofStandardbred trotters in training Equine Comp Exerc Physiol1 107ndash117 httpsdoiorg101079ECEP200312 2004

Loitsch C Kinematische Untersuchung uumlber den Canter von Pfer-den (Equus caballus) Ruhr Universitaumlt Bochum 1993

Morrice-West A V Hitchens P L Walmsley E A Steven-son M A Wong A S M and Whitton R C Variationin GPS and accelerometer recorded velocity and stride pa-rameters of galloping Thoroughbred horses Equine Vet Jhttpsdoiorg101111evj13370 online first 2020

Mazzetta G V and Blanco E R Speeds of dinosaurs from theAlbian-Cenomanian of Patagonia and sauropod stance and gaitActa Palaeontol Pol 46 235ndash246 2001

McCoy A M Beeson S K Rubin C-J Andersson L Ca-puto P Lykkjen Moore A Piercy R J Mickelson J Rand McCue M E Identification and validation of genetic vari-ants predictive of gait in Standardbred horses PLoS Genet 15e1008146 httpsdoiorg101371journalpgen1008146 2019

McNeil P Mills L V Tolman M S and Kooyman B Sig-nificance of latest Pleistocene tracks trackways and tramplegrounds from Southern Alberta Canada in Cenozoic Verte-brate Tracks and Traces edited by Lucas S G Spielmann JA and Lockley M G New Mexico Museum of Natural Historyand Science 209ndash223 2007

Merriam J C Tertiary mammalian faunas of the Mojave DesertBull Dept Geol Univ Calif 11 437ndash585 1919

Nicodemus M C and Booker J E Two-dimensional kine-matics of the jog and lope of the stock breed west-ern pleasure horse Equ Comp Exer Physiol 4 59ndash70httpsdoiorg101017S1478061507811467 2007

Nicodemus M C and Clayton H M Temporal variables of the4-beat stepping jog and lope in Proceedings of the SeventeenthEquine Nutrition and Physiology Symposium Equine Nutritionand Physiology Society 247ndash252 2001



Nicodemus M C and Clayton H M Temporal variables of four-beat stepping gaits of gaited horses Appl Anim Behav Sci80 133ndash142 httpsdoiorg101016S0168-1591(02)00219-82003

Nicodemus M C and Slater K Forelimb kinemat-ics of the flat walk and fox trot of the MissouriFox Trotter Comp Exerc Physiol 6 149ndash156httpsdoiorg101017S1755254010000048 2009

Nicodemus M C Holt K M and Swartz K Relation-ship between velocity and temporal variables of the flatshod running walk Eqine Veter J Sup 34 340ndash343httpsdoiorg101111j2042-33062002tb05444x 2002

Novoa-Bravo M Jaumlderkvist Fegraeus K Rhodin M Strand EGarciacutea L F and Lindgren G Selection on the ColombianPaso Horsersquos gaits has produced kinematic differences partlyexplained by the DMRT3 gene PLoS Genet 14 e0212149httpsdoiorg101371journalpone0202584 2018

Nyborg T Buccheim P and Nick K E Age stratigraphy de-positional environment and vertebrate ichnology of the PlioceneCopper Canyon Formation Death Valley California in Search-ing for the Pliocene Southern Exposures edited by ReynoldsR E California State University Desert Studies Center 114ndash124 2012

Onar V Kahvecioglu K O Olgun Erdikmen D Alpak H andParkan Yaramis Ccedil The estimation of withers height of ancienthorse New estimation formulations by using the metacarpalmeasurements of living horse Rev Med Vet 169 157ndash1652018

Pagnac D Scaphohippus a new genus of horse (MammaliaEquidae) from the Barstow Formation of California J MammEvol 13 37ndash61 httpsdoiorg101007s10914-005-9002-22006

Pajak A F and Vincelette A R ldquoMerychippusrdquo stylodontus andldquoMrdquo intermontanus Biostratigraphy and basic morphology oftwo Barstovian tridactyl horses San Bernadino County MuseumAssoc Q 38 80ndash85 1991

Parsons K J Pfau T and Wilson A M High-speed gal-lop locomotion in the Thoroughbred racehorse I The effectof incline on stride parameters J Exp Biol 211 935ndash944httpsdoiorg101242jeb006650 2008

Pecha A Rumpler B Kotschwar A and Licka T Der Einflussvon unterschiedlich schweren Ballenboots in zwei verschiedenenTempi auf die Dauer und den Beginn der Stuumltzbeinphase in derGangart Toumllt des Islandpferdes Pferdeheilkunde 27 687ndash6942011

Promerovaacute M Andersson L S Juras R Penedo M C TReissmann M Tozaki T Bellone R Dunner S HoriacutenP Imsland F Imsland P Mikko S Modryacute D Roed KH Schwochow D Vega-Pla J L Mehrabani-Yeganeh HYousefi-Mashouf N Cothran E G Lindgren G and An-derssonet L Worldwide frequency distribution of the ldquoGaitkeeperrdquo mutation in the DMRT3 gene Anim Genet 45 274ndash282 httpsdoiorg101111age12120 2014

Prost J H Gaits of monkeys and horses A methodolog-ical critique Am J Physiol Anthropol 32 121ndash128httpsdoiorg101002ajpa1330320114 1970

Regatieri I C Eberth J E Sarver F Lear T L and BaileyE Comparison of DMRT3 genotypes among American Saddle-

bred horses with reference to gait Anim Genet 47 603ndash605httpsdoiorg101111age12458 2016

Remeika P Fossil footprints of Anza-Borrego in Fossil Treasuresof the Anza-Borrego Desert The Last Seven Million Years ElCajon edited by Jefferson G T and Lindsay L Sunbelt Pub-lications San Diego California 311ndash327 2006

Renders E The gait of Hipparion sp from fossil foot-prints in Laetoli Tanzania Nature 308 179ndash181httpsdoiorg101038308179a0 1984a

Renders E Corrigendum to ldquoThe gait of Hipparion sp fromfossil footprints in Laetoli Tanzaniardquo Nature 308 866httpsdoiorg101038308866a0 1984b

Reynolds R E Pleistocene mammal tracks near Shoshone south-ern Death Valley California San Bernadino County MuseumAssoc Q 46 27ndash29 1999

Reynolds R E Horse hoof prints in the fossil record in Mak-ing Tracks Across the Southwest The 2006 Desert Symposiumedited by Reynolds R E California State University DesertStudies Consortium and LSA Associates 25ndash28 2006

Robilliard J J Pfau T and Wilson A M Gait characterisa-tion and classification in horses J Exp Biol 210 187ndash197httpsdoiorg101242jeb02611 2007

Sarjeant W A S and Reynolds R E Camel and horse footprintsfrom the Miocene of California and Nevada San Bernadino Mu-seum Assoc Q 46 3ndash20 1999

Santucci V L Tweet J Bustos D Nyborg T and Hunts A PAn inventory of Cenozoic Fossil Vertebrate Tracks and Burrowsin National Park Service Areas New Mexico Museum Nat HistSci Bull 62 469ndash488 2014

Seder J A and Vickery C E Double and triple fully air-borne phases in the gaits of racing speed Thoroughbreds JEquine Vet Sci 23 S73ndashS81 httpsdoiorg101016S0737-0806(03)70018-5 2003a

Seder J A and Vickery C E Temporal and kinematic gait vari-ables of Thoroughbred racehorses at or near racing speeds JEquine Vet Sci 23 S82ndashS112 httpsdoiorg101016S0737-0806(03)70019-7 2003b

Serra Braganccedila F M Broomeacute S Rhodin M Bjoumlrnsdoacutettir SGunnarsson V Voskamp J P Persson-Sjodin E Back WLindgren G Novoa-Bravo M Roepstorff C Van der ZwaagB J Van Weeren P R and Hernlund E Improving gait clas-sification in horses by using inertial measurement unit (IMU)generated data and machine learning Sci Rep 10 17785httpsdoiorg105167uzh-192795 2020

Serra Braganccedila F M Broomeacute S Rhodin M Bjoumlrnsdoacutettir SGunnarsson V Voskamp J P Persson-Sjodin E Back WLindgren G Novoa-Bravo M Roepstorff C Van der ZwaagB J Van Weeren P R and Hernlund E Corrigendum toldquoImproving gait classification in horses by using inertial mea-surement unit (IMU) generated data and machine learningrdquoSci Rep 11 9379 httpsdoiorg101038s41598-020-73215-9 2021

Smith F A manual of veterinary physiology Bailliegravere Tindall andCox London 1912

Soleacute M Goacutemez M D Martiacutenez Galisteo A SantosR and Valera M Kinematic characterization of theMenorca Horse at the walk and the trot Influence ofhind limb pastern angle J Equine Vet Sci 33 726ndash733httpsdoiorg101016jjevs201212002 2013



Splan R K and Hunter H B Temporal variables of the canter ofthe Tennessee Walking Horse Equine Comp Exerc Physiol 141ndash44 httpsdoiorg101079ECP20033 2004

Stachurska A Kolstrung R Pieta M and Silmanowicz PDifferentiation between fore and hind hoof dimensions inthe horse (Equus caballus) Arch Tierzucht 51 531ndash540httpsdoiorg105194aab-51-531-2008 2008

Stachurska A Kolstrung R Pieta M and Silmanowicz P Hoofsize as related to body size in the horse (Equus caballus) AnimSci Pap Rep 29 213ndash222 2011

Staiger E A Almeacuten M S Promerovaacute M Brooks S CothranE G Imsland F Jaumlderkvist Fegraeus K Lindgren G Mehra-bani Yeganeh H Mikko S Vega-Pla J L Tozaki T Ru-bin C J and Andersson L The evolutionary history of theDMRT3 ldquoGait keeperrdquo haplotype Anim Genet 48 551ndash559httpsdoiorg101111age12580 2017

Starke S D Robilliard J J Weller R Wilson A M and PfauT Walk-run classification of symmetrical gaits in the horse Amultidimensional approach J Roy Soc Interface 6 335ndash342httpsdoiorg101098rsif20080238 2009

Stefaacutensdoacutettir G J Jansson A Ragnarsson S and Gun-narsson V Speed of gaits in Icelandic horses and rela-tionships to sex age conformation measurements and sub-jective judgesrsquo scores Comp Exerc Physiol 17 151ndash160httpsdoiorg103920CEP200039 2021

Stevens K A Ernst S and Marty D Uncertainty and ambi-guity in the interpretation of sauropod trackways in DinosaurTracks The Next Steps edited by Falkingham P L Marty Dand Richter A Indiana University Press 227ndash244 2016

Streitlein I and Preuschoft H Die Kinematik der Trabtempi vonReitpferden in Studien zu den Bewegungen von Sportpferdenedited by Preuschoft H Fritz M Huellen-Kluge K KniselG and Streitlein I Deutsche Reiterliche Vereinigung Waren-dorf Germany 20ndash65 1987

Takahashi T Aoki O and Hiraga A Running form characteris-tics of the Triple Crown winner in Japan J Equine Vet Sci 1847ndash53 httpsdoiorg101294jes1847 2007

Thompson M E White Jr R S and Morgan G S Pace ver-sus trot Can medium speed gait be determined from fossil track-ways in Cenozoic Vertebrate Tracks and Traces edited by Lu-cas S G Spielmann J A and Lockley M G New MexicoMuseum of Natural History and Science 309ndash314 2007

Thulborn R A Speeds and gaits of dinosaurs Palaeo-geogr Palaeocl 38 227ndash256 httpsdoiorg1010160031-0182(82)90005-0 1982

Thulborn R A The gait of dinosaurs in Dinosaur Tracks andTraces edited by Gillett D D and Lockley M G CambridgeUniversity Press 39ndash50 1989

Van der Made J The large mammals of the Plio-Pleistoceneof Africa Afrotheria Perissodactyla and Artiodactyla I in LaCuna de la Humanidad edited by Enriacutequez S and AlvaradoE Museo Arqueloacutegico Regional Alcalaacute de Henares amp Museode la Evolucioacuten Humana 324ndash336 2014

Waldern N M Wiestner T Ramseier L C and Weishaupt MA Comparison of limb loading and movement of Icelandichorses while toumllting and trotting at equal speeds Am J Vet Res76 1031ndash1040 httpsdoiorg102460ajvr76121031 2015

Walker V A Tranquille C A Newton J R Dyson S JBrandham J Northrop A J and Murray R C Com-parison of limb kinematics between collected and length-ened (mediumextended) trot in two groups of dressage horseson two different surfaces Equine Vet J 49 673ndash680httpsdoiorg101111evj12661 2017

Webb S D Locomotor evolution in camels Forma Functio 5 99ndash112 1972

Weishaupt M A Bystroumlm A Geser-von Peinen KWiestner T Meyers H Waldern N Johnston CVan Weeren R and Roepstorff L Kinetics and kine-matics of the passage Equine Vet J 41 263ndash276httpsdoiorg102746042516409x397226 2009

Weishaupt M A Hogg H P Auer J A and Weistner TVelocity-dependent changes of time force and spatial parame-ters in Warmblood horses walking and trotting on a treadmillEquine Vet J Sup 38 530ndash537 httpsdoiorg101111j2042-3306201000190x 2010

Wilson B D Neal R Howard A and Groenendyk SThe gait of pacers 1 Kinematics of the racing strideEquine Vet J 20 341ndash346 httpsdoiorg101111j2042-33061988tb01542x 1988a

Witte T H Hirst C V and Wilson A M Effect of speed onstride parameters in racehorses at gallop in field conditions JExp Biol 209 4389ndash4397 httpsdoiorg101242jeb025182006

Wutke S The origin of ambling horses Curr Biol 26 R697ndashR699 httpsdoiorg101016jcub201607001 2016

Ziegler L Easy-gaited horses Storey Publishing North AdamsMassachusetts 2005

Zips S Peham C Scheidl M Licka T and Girtler D Mo-tion pattern of the toelt of Icelandic horses at different speedsEquine Vet J 33 109ndash111 httpsdoiorg101111j2042-33062001tb05371x 2001


Abstract

Introduction

Symmetrical laterally dissociated gaits

Symmetrical diagonally coupled gaits

Symmetrical laterally coupled gaits

Asymmetrical gaits

Methods and materials

Results

Observable and measurable differences between footprint patterns within modern horse gaits

Description and measurements of fossil horse tracks

Discussion

Conclusion

Sample availability

Supplement

Competing interests

Acknowledgements

Review statement

References


11 Symmetrical laterally dissociated gaits

Symmetrical laterally dissociated gaits are those wherein thelimbs chiefly operate independently of each other begin-ning with a sequence of limbs moving one after the otheron one side of the horse followed by a similar sequence onthe horsersquos other side (hence such gaits have sometimes beendescribed as bipedal or square) This almost always involvesa footfall pattern of left hind (LH) left front (LF) right hind(RH) and right front (RF) Such gaits include the walk pasofino and running walk of horses

The walk is the natural slow-speed gait of the horse It oc-curs at a typical speed of 14ndash18 ms and with a cycle (stride)length of 157ndash193 cm Because it involves laterally dissoci-ated and isochronous limb movements it is a four-beat gaitIt is also a non-suspended gait as there is at least one footon the ground at all times In fact in the walk there are typi-cally two or three limbs supporting the horsersquos weight at alltimes or more particularly a triangular support structure fol-lowed by alternating lateral and diagonal bases of supportThis makes the walk quite stable and easy on the horse Moretechnically the walk has a duty factor around 06 as each limbis on the ground for around 60 of the stride and a stride fre-quency of around 08ndash11 strides per second depending uponthe speed The walk can occur at slow (12ndash13 ms) medium(13ndash22 ms) or fast (22ndash30 ms) rates Horses can alsoengage in a collected walk with short quick and elevatedmarching steps around 150ndash160 cm in length or an extendedwalk with longer and less frequent steps around 180ndash200 cmin length In slow and collected walks the three-legged sup-port structure dominates and the hind feet tend to make con-tact with the ground behind (undertracking) or overlapping(capping) the ipsilateral front feet In medium-speed (work-ing) walks the hind feet typically contact the ground just infront of the ipsilateral front feet Finally in extended and fastwalks the hind hooves often overtrack (overstep) the ipsilat-eral front hooves The walk will normally transition to thetrot at high speeds (Clayton 1995 Nicodemus and Slater2009 Weishaupt et al 2010 Soleacute et al 2013)

There also exist some ldquoartificialrdquo laterally dissociated gaitsfound in specialized horse breeds These artificial gaits likethe standard walk are isochronal four-beat symmetrical gaitsand display the same footfall sequence of left hind left frontright hind and right front but are modified in various waysmost often so that the gait is smoother for the rider

The paso fino of Columbian Paso horses is a slow (09ndash13 ms) walking gait but one that is highly collected withhigh and quick steps (stride frequency around 26 stridess)one possessing a duty factor of 055 In the paso fino thehind feet will usually undertrack the ipsilateral front feetby a considerable distance and so contralateral feet comedown near each other forming diagonal couplets As it isslow and collected there are always at least three feet on theground for increased support and a comfortable gait that can

be sustained for a long time (Nicodemus and Clayton 2003Novoa-Bravo et al 2018)

The running walk (slow amble paso llano) is the artificialmedium to fast gait of Tennessee Walking Spotted Saddleand Peruvian Paso horses The running walk can occur atmedium (ca 27 ms) to fast (ca 38ndash41 ms) speeds It pos-sesses an extended cycle length wherein the hind feet over-track the ipsilateral front feet by several inches forming lat-eral couplets at medium speeds four individual imprints atfast speeds and diagonal couplets at very fast speeds as theoverstep exceeds 25 of the cycle length This results in thelimbs being on the ground 40 to 50 of the stride cycle(ie a duty factor of 04 to 05) and the body being occa-sionally supported by only one limb as opposed to the con-tinual two or three limb support in the standard walk Still asthe support structure in the running walk typically involvesan ipsilateral or diagonal two-limb support structure alongwith a brief tripedal support period it is a smooth gait for therider (Renders 1984a b Nicodemus et al 2002) TennesseeWalking and Missouri Foxtrotting horses can also exhibit aslower variation in the running walk the flat walk again withextended strides and overtracking but at a speed of only 2ndash3 ms

12 Symmetrical diagonally coupled gaits

The trot is the natural medium to fast gait of the horse whichis an isochronal diagonally coupled two-beat gait whereincontralateral front and hind limbs move in a coordinatedmanner lifting off the ground in sync swinging togetherand striking the ground nearly at the same time (the hind-foot sometimes contacts the ground just before the front footor vice versa) forming lateral couplets The two-beat foot-fall sequence of the trot is hence LH+RFminusRH+LF Thisresults in two suspended phases in the stride wherein all fourfeet are off the ground (for 9 of stride duration) The trothas a typical duty factor of 035ndash045 and a frequency of 15ndash20 stridess Like the walk the standard trot can occur at dif-ferent speeds slow (jog) at speeds of 25ndash36 ms with mod-erate undertracking medium at speeds of 36ndash54 ms withcapping of hoofs or fast at speeds of 54ndash90 ms with over-tracking of front feet by hind feet The cycle (stride) length ofthe trot is typically around 200ndash450 cm The trot may also becollected or extended The collected trot employs short high-stepping and quick strides and often undertracks as in Hack-ney and Morgan horses and can have a duty factor up to 06The extended trot is a fast trot with long strides increasedsuspension phases and a great deal of overtracking (Stre-itlein and Preuschoft 1987 Clayton 1994 Holmstroumlm et al1994 Leleu et al 2004 Weishaupt et al 2010 Hobbs et al2016 Walker et al 2017) The Standardbred horse can per-form an extremely fast flying trot at speeds of 100ndash142 msa stride frequency of 25 stridess and a cycle length of 500ndash600 cm The flying-trot beats are asynchronous (irregular)with an abaxial lateral offset of the hind limbs and turns




































2ndash3 Lateral 0

Runningwalk



0


3 Lateral 0

Fox trotand trocha



0


0ndash2 Lateral 2


1ndash2 Lateral 2



Toumllt orrack



0



2



1


4(2+ 2)





3 Results






Gait Speed(ms)

Cycle length(cm)










Fox trotand trocha





























Cyclelength(cm)







na not applicable















Gait Cyclelength

height




cycle length




cycle length

Slow walk 095087K

034 and 036029 and 033K


003 and 0010007 and 0009K

019 and 006008 and 009K

Fast walk 110119K

036 and 032036 and 030K

005 and 002019 and 006K

005 and 0020 and 0K

031 and 010007 and 006K

Runningwalk

135 027 and 020 058 and 012na and ca 014R

na na

Slow trot 123140K

045 and 037(056 and 040K)


005 and 002002 and 001K

022 and 008006 and 004K

Fast trot 171174K

066 and 039066 and 038K


005 and 0020006 and 0003K

014 and 005013 and 008K



118K

071 and 036056 and 032V

027 and 023K



005 and 002010 and 003V

002 and 002K

026 and 009040 and 013V

019 and 016K

Pace 181V

256K063 and 034V

077 and 030K029 and 009V

021 and 006K013 and 004V

004 and 001K034 and 011V

016 and 006K

Canter 160153K

041 and 026039 and 026K

003 and 0010006 and 0002K

011 and 002004 and 002K

033 and 007009 and 006K

Gallop 191175K

039 and 020(033 and 019K)

na na na



4 Discussion








Cycle length(cm)





na na


ca 37 Ma ca 65 ca 1320 ca 12 18 ca 36 36 ca 52 (21) 53 (27)


ca 37 Ma ca 65 ca 1395 ca 27 35 ca 24 30 ca 53 (27) 53 (33)




18 (110)13 (ca 111)



Species Stride

heightSpeed(ms)


Overtrack







117 22 032 and 027 240 and 027 ca 0 021 and 018


123 24 027 and 022 087 and 019 ca 15 026 and 022
























5 Conclusion














References






















































































































Abstract

Introduction




Asymmetrical gaits


Results



Discussion

Conclusion

Sample availability

Supplement

Competing interests

Acknowledgements

Review statement

References



































2ndash3 Lateral 0

Runningwalk



0


3 Lateral 0

Fox trotand trocha



0


0ndash2 Lateral 2


1ndash2 Lateral 2



Toumllt orrack



0



2



1


4(2+ 2)





3 Results






Gait Speed(ms)

Cycle length(cm)










Fox trotand trocha





























Cyclelength(cm)







na not applicable















Gait Cyclelength

height




cycle length




cycle length

Slow walk 095087K

034 and 036029 and 033K


003 and 0010007 and 0009K

019 and 006008 and 009K

Fast walk 110119K

036 and 032036 and 030K

005 and 002019 and 006K

005 and 0020 and 0K

031 and 010007 and 006K

Runningwalk

135 027 and 020 058 and 012na and ca 014R

na na

Slow trot 123140K

045 and 037(056 and 040K)


005 and 002002 and 001K

022 and 008006 and 004K

Fast trot 171174K

066 and 039066 and 038K


005 and 0020006 and 0003K

014 and 005013 and 008K



118K

071 and 036056 and 032V

027 and 023K



005 and 002010 and 003V

002 and 002K

026 and 009040 and 013V

019 and 016K

Pace 181V

256K063 and 034V

077 and 030K029 and 009V

021 and 006K013 and 004V

004 and 001K034 and 011V

016 and 006K

Canter 160153K

041 and 026039 and 026K

003 and 0010006 and 0002K

011 and 002004 and 002K

033 and 007009 and 006K

Gallop 191175K

039 and 020(033 and 019K)

na na na



4 Discussion








Cycle length(cm)





na na


ca 37 Ma ca 65 ca 1320 ca 12 18 ca 36 36 ca 52 (21) 53 (27)


ca 37 Ma ca 65 ca 1395 ca 27 35 ca 24 30 ca 53 (27) 53 (33)




18 (110)13 (ca 111)



Species Stride

heightSpeed(ms)


Overtrack







117 22 032 and 027 240 and 027 ca 0 021 and 018


123 24 027 and 022 087 and 019 ca 15 026 and 022
























5 Conclusion














References






















































































































Abstract

Introduction




Asymmetrical gaits


Results



Discussion

Conclusion

Sample availability

Supplement

Competing interests

Acknowledgements

Review statement

References



Gait Speed(ms)

Cycle length(cm)










Fox trotand trocha





























Cyclelength(cm)







na not applicable















Gait Cyclelength

height




cycle length




cycle length

Slow walk 095087K

034 and 036029 and 033K


003 and 0010007 and 0009K

019 and 006008 and 009K

Fast walk 110119K

036 and 032036 and 030K

005 and 002019 and 006K

005 and 0020 and 0K

031 and 010007 and 006K

Runningwalk

135 027 and 020 058 and 012na and ca 014R

na na

Slow trot 123140K

045 and 037(056 and 040K)


005 and 002002 and 001K

022 and 008006 and 004K

Fast trot 171174K

066 and 039066 and 038K


005 and 0020006 and 0003K

014 and 005013 and 008K



118K

071 and 036056 and 032V

027 and 023K



005 and 002010 and 003V

002 and 002K

026 and 009040 and 013V

019 and 016K

Pace 181V

256K063 and 034V

077 and 030K029 and 009V

021 and 006K013 and 004V

004 and 001K034 and 011V

016 and 006K

Canter 160153K

041 and 026039 and 026K

003 and 0010006 and 0002K

011 and 002004 and 002K

033 and 007009 and 006K

Gallop 191175K

039 and 020(033 and 019K)

na na na



4 Discussion








Cycle length(cm)





na na


ca 37 Ma ca 65 ca 1320 ca 12 18 ca 36 36 ca 52 (21) 53 (27)


ca 37 Ma ca 65 ca 1395 ca 27 35 ca 24 30 ca 53 (27) 53 (33)




18 (110)13 (ca 111)



Species Stride

heightSpeed(ms)


Overtrack







117 22 032 and 027 240 and 027 ca 0 021 and 018


123 24 027 and 022 087 and 019 ca 15 026 and 022
























5 Conclusion














References






















































































































Abstract

Introduction




Asymmetrical gaits


Results



Discussion

Conclusion

Sample availability

Supplement

Competing interests

Acknowledgements

Review statement

References















Cyclelength(cm)







na not applicable















Gait Cyclelength

height




cycle length




cycle length

Slow walk 095087K

034 and 036029 and 033K


003 and 0010007 and 0009K

019 and 006008 and 009K

Fast walk 110119K

036 and 032036 and 030K

005 and 002019 and 006K

005 and 0020 and 0K

031 and 010007 and 006K

Runningwalk

135 027 and 020 058 and 012na and ca 014R

na na

Slow trot 123140K

045 and 037(056 and 040K)


005 and 002002 and 001K

022 and 008006 and 004K

Fast trot 171174K

066 and 039066 and 038K


005 and 0020006 and 0003K

014 and 005013 and 008K



118K

071 and 036056 and 032V

027 and 023K



005 and 002010 and 003V

002 and 002K

026 and 009040 and 013V

019 and 016K

Pace 181V

256K063 and 034V

077 and 030K029 and 009V

021 and 006K013 and 004V

004 and 001K034 and 011V

016 and 006K

Canter 160153K

041 and 026039 and 026K

003 and 0010006 and 0002K

011 and 002004 and 002K

033 and 007009 and 006K

Gallop 191175K

039 and 020(033 and 019K)

na na na



4 Discussion








Cycle length(cm)





na na


ca 37 Ma ca 65 ca 1320 ca 12 18 ca 36 36 ca 52 (21) 53 (27)


ca 37 Ma ca 65 ca 1395 ca 27 35 ca 24 30 ca 53 (27) 53 (33)




18 (110)13 (ca 111)



Species Stride

heightSpeed(ms)


Overtrack







117 22 032 and 027 240 and 027 ca 0 021 and 018


123 24 027 and 022 087 and 019 ca 15 026 and 022
























5 Conclusion














References






















































































































Abstract

Introduction




Asymmetrical gaits


Results



Discussion

Conclusion

Sample availability

Supplement

Competing interests

Acknowledgements

Review statement

References










Gait Cyclelength

height




cycle length




cycle length

Slow walk 095087K

034 and 036029 and 033K


003 and 0010007 and 0009K

019 and 006008 and 009K

Fast walk 110119K

036 and 032036 and 030K

005 and 002019 and 006K

005 and 0020 and 0K

031 and 010007 and 006K

Runningwalk

135 027 and 020 058 and 012na and ca 014R

na na

Slow trot 123140K

045 and 037(056 and 040K)


005 and 002002 and 001K

022 and 008006 and 004K

Fast trot 171174K

066 and 039066 and 038K


005 and 0020006 and 0003K

014 and 005013 and 008K



118K

071 and 036056 and 032V

027 and 023K



005 and 002010 and 003V

002 and 002K

026 and 009040 and 013V

019 and 016K

Pace 181V

256K063 and 034V

077 and 030K029 and 009V

021 and 006K013 and 004V

004 and 001K034 and 011V

016 and 006K

Canter 160153K

041 and 026039 and 026K

003 and 0010006 and 0002K

011 and 002004 and 002K

033 and 007009 and 006K

Gallop 191175K

039 and 020(033 and 019K)

na na na



4 Discussion








Cycle length(cm)





na na


ca 37 Ma ca 65 ca 1320 ca 12 18 ca 36 36 ca 52 (21) 53 (27)


ca 37 Ma ca 65 ca 1395 ca 27 35 ca 24 30 ca 53 (27) 53 (33)




18 (110)13 (ca 111)



Species Stride

heightSpeed(ms)


Overtrack







117 22 032 and 027 240 and 027 ca 0 021 and 018


123 24 027 and 022 087 and 019 ca 15 026 and 022
























5 Conclusion














References






















































































































Abstract

Introduction




Asymmetrical gaits


Results



Discussion

Conclusion

Sample availability

Supplement

Competing interests

Acknowledgements

Review statement

References





Cycle length(cm)





na na


ca 37 Ma ca 65 ca 1320 ca 12 18 ca 36 36 ca 52 (21) 53 (27)


ca 37 Ma ca 65 ca 1395 ca 27 35 ca 24 30 ca 53 (27) 53 (33)




18 (110)13 (ca 111)



Species Stride

heightSpeed(ms)


Overtrack







117 22 032 and 027 240 and 027 ca 0 021 and 018


123 24 027 and 022 087 and 019 ca 15 026 and 022
























5 Conclusion














References






















































































































Abstract

Introduction




Asymmetrical gaits


Results



Discussion

Conclusion

Sample availability

Supplement

Competing interests

Acknowledgements

Review statement

References


















5 Conclusion














References






















































































































Abstract

Introduction




Asymmetrical gaits


Results



Discussion

Conclusion

Sample availability

Supplement

Competing interests

Acknowledgements

Review statement

References







References






















































































































Abstract

Introduction




Asymmetrical gaits


Results



Discussion

Conclusion

Sample availability

Supplement

Competing interests

Acknowledgements

Review statement

References





























































































Abstract

Introduction




Asymmetrical gaits


Results



Discussion

Conclusion

Sample availability

Supplement

Competing interests

Acknowledgements

Review statement

References

determining the gait of miocene, pliocene, and pleistocene

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