A diverse Pleistocene marsupial trackway assemblage from the Victorian Volcanic Plains, Australia

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Abstract

A diverse assemblage of late Pleistocene marsupial trackways on a lake bed in south-western Victoria provides the first information relating to the gaits and morphology of several megafaunal species, and represents the most speciose and best preserved megafaunal footprint site in Australia. The 60–110 ka volcaniclastic lacustrine sedimentary rocks preserve trackways of the diprotodontid Diprotodon optatum, a macropodid (probably Protemnodon sp.) and a large vombatid (perhaps Ramsayia magna or ‘Phascolomysmedius) and possible prints of the marsupial lion, Thylacoleo carnifex. The footprints were imprinted within a short time period, demonstrating the association of the taxa present, rather than the time-averaged accumulations usually observed in skeletal fossil deposits. Individual manus and pes prints are distinguishable in some trackways, and in many cases some digital pad morphology is also present. Several parameters traditionally used to differentiate ichnotaxa, including trackway gauge and the degree of print in-turning relative to the midline, are shown to be subject to significant intraspecific variation in marsupials. Sexual dimorphism in the trackway proportions of Diprotodon, and its potential for occurrence in all large bodied, quadrupedal marsupials, is identified here for the first time.

Introduction

Fossil trackways commonly preserve characteristics of organisms not available from their skeletal fossil record. Trackways can provide insight into the biomechanics and palaeobiology of a species not evident from the skeleton (Lockley, 1998). It may be possible to determine the gait, foot morphology, size and speed of travel of individuals, as well as factors of wider ecological importance, such as community composition and species diversity (Camens and Wells, 2009). In addition, the rheology of the sediments preserving the prints can reveal aspects of the environment at the time of deposition (Allen, 1989, Allen, 1997).

Mammalian trackways have been widely studied in many parts of the world (e.g. Leakey and Hay, 1979, Belperio and Fotheringham, 1990, Cohen et al., 1993, Lea, 1996, Allen, 1997, Lockley et al., 1999, Ataabadi and Sarjeant, 2000, Mietto et al., 2003, Triggs, 2004, Webb et al., 2006), as have those of dinosaurs (e.g. Alexander, 1976, Thulborn and Wade, 1984, Lockley, 1986a, Thulborn, 1989, Thulborn, 1990, Farlow et al., 2000). However, mammalian fossil trackways are rare in Australia, the five described sites being restricted to the Pliocene and Pleistocene. These sites include late Pleistocene human footprints at the Willandra Lakes in New South Wales (Webb et al., 2006) and Holocene human footprints at Clare Bay in South Australia (Belperio and Fotheringham, 1990). Marsupial traces include macropodid (possibly Protemnodon) footprints, from near Clare Bay (Belperio and Fotheringham, 1990), Pleistocene Diprotodon footprints at Lake Callabonna (Tedford, 1973, Wells and Tedford, 1995) and Pliocene Euowenia grata footprints from the Warburton River (Camens and Wells, 2009), all in South Australia, and kangaroo tracks from the Willandra Lakes, New South Wales (Webb et al., 2006). The site described below thus contains more fossil marsupial footprints than have previously been described for the whole of the Australian Quaternary.

Most fossil mammal trackways previously described were created by hooved ungulates (e.g. Laporte and Behrensmeyer, 1980, Loope, 1986, Allen, 1989, Allen, 1997, Lea, 1996, Lockley et al., 1999, Fornós et al., 2002), their hard hooves having the potential to leave tracks both deeper and in a wider range of substrates than the soft-footed marsupials. This may help to explain the paucity of fossil mammal footprints in Australia, as the soft feet of all members of the Australian fauna would leave shallower tracks that are less clearly defined and less likely to be preserved.

Here we describe the most diverse assemblage of marsupial trackways yet discovered in Australia. Their superb preservation allows us to determine the trackmakers at familial, generic or even species level. In the case of the most spectacular trackway, we are able to estimate the animal’s speed and suggest its sex. Our geological analysis provides temporal context for the trackways together with an understanding of the environment in which they were active. Accordingly, we aim to shine a light on the late Pleistocene ecosystem of the fertile and well watered volcanic plains of south-eastern Australia.

Section snippets

Regional setting

The megafaunal marsupial trackways occur on a lake margin within the Victorian Volcanic Plains (VVP) of south-eastern Australia (Fig. 1). Details of the location are not provided here because a plan of management to protect the locality from human interference and the elements has not yet been developed. Those details are, however, held at Museum Victoria, Melbourne, in the documentation of six moulds and casts taken from the trackways (MV P230853 to P230858). The unnamed lithostratigraphic

Trackway mapping

The position, length and width of each footprint were recorded on a gridded plan using tape measure and compass. A more or less continuous series of footprints made by one individual as it traversed the site was defined as a trackway. For the diprotodontid trackways the length, width and depth of each print were measured and its distance from an arbitrary datum recorded. Stride length was measured as the distance between corresponding points on successive footprints. Trackway width was measured

Geological description

The trackways occur in volcaniclastic rocks, while associated vertebrate skeletal fossils were found in pockets of sandy mud and ferruginised sandstone that exist within the volcaniclastics. The thickness of the exposed strata is less than 0.5 m. Two contrasting units are present, the lower one being volcaniclastic and the upper one a micritic carbonate. Eight short cores (8–29 cm long) were extracted from the lower unit within the confines of the grid.

Palaeoenvironment

It has been suggested that the environments most conducive to footprint preservation are lake and river margins (Cohen et al., 1993, Mustoe, 2002). The VVP trackways exposure is at the edge of a modern lake and, although the configuration of the lake is probably vastly changed since the trackways formed, the sedimentological evidence strongly supports a lacustrine setting for the host sediments. First- and second-order bed forms (parallel sand bars and ripples) are aqueous in origin, formed at

Conclusion

The VVP assemblage of Pleistocene trace fossils is the taxonomically most diverse group of marsupial trackways known. In addition to diprotodontid, macropodid, vombatid and possible thylacoleonid trackways, the locality also yields trace fossils of invertebrates and plants. Well preserved sedimentary features show that the trackmakers were attracted to a lake which, at some time after the formation of the trackways, changed from near-fresh to saline. The diprotodontid, if correctly identified

Acknowledgements

We thank an anonymous farming family of the Victorian Volcanic Plains who have protected the trackways for decades; Parks Victoria staff, especially John Clarke, Frank Gleeson, Dave Jenson and Rob Wallis; Peter Swinkels and his crew of preparators from Museum Victoria who moulded major sections of the trackways; students, staff and friends of the University of Ballarat and DAP’s crew of volunteers who helped lay out the grid, measure the tracks and excavate the skeletal fossils; and Matt Gibson

References (82)

  • R. Grün

    The relevance of parametric U–uptake models in ESR age calculations

    Radiation Measurements

    (2009)
  • J. Hellstrom

    U–Th dating of speleothems with high initial 230Th using stratigraphical constraint

    Quaternary Geochronology

    (2006)
  • P.P. Hesse

    The record of continental dust from Australia in Tasman Sea sediments

    Quaternary Science Reviews

    (1994)
  • P.D. Lea

    Vertebrate tracks in Pleistocene eolian sand-sheet deposits of Alaska

    Quaternary Research

    (1996)
  • M. Lockley et al.

    The first sauropod trackways from China

    Cretaceous Research

    (2002)
  • A.S. Murray et al.

    Measurement of the equivalent dose in quartz using a regenerative-dose single-aliquot protocol

    Radiation Measurements

    (1998)
  • A.S. Murray et al.

    Luminescence dating of quartz using an improved single-aliquot regenerative-dose protocol

    Radiation Measurements

    (2000)
  • J.R. Prescott et al.

    Cosmic ray and gamma ray dosimetry for TL and ESR

    Nuclear Tracks and Radiation Measurement

    (1988)
  • J.R. Prescott et al.

    Cosmic ray contributions to dose rates for luminescence and ESR dating: large depths and long-term time variations

    Radiation Measurements

    (1994)
  • S. Webb et al.

    Pleistocene human footprints from the Willandra Lakes, southeastern Australia

    Journal of Human Evolution

    (2006)
  • G. Adamiec et al.

    Dose-rate conversion factors: update

    Ancient TL

    (1998)
  • R.M. Alexander

    Estimates of speeds of dinosaurs

    Nature

    (1976)
  • R.M. Alexander

    The gaits of bipedal and quadrupedal animals

    The International Journal of Robotic Research

    (1984)
  • J.R.L. Allen

    Fossil vertebrate tracks and indenter mechanics

    Journal of the Geological Society of London

    (1989)
  • J.R.L. Allen

    Subfossil mammalian tracks (Flandrian) in the Severn Estuary, S.W. Britain: mechanics of formation, preservation and distribution

    Philosophical Transactions of the Royal Society of London B

    (1997)
  • P. Bang

    Animal Tracks and Signs

    (2001)
  • A.P. Belperio et al.

    Geological setting of two Quaternary footprint sites, western South Australia

    Australian Journal of Earth Sciences

    (1990)
  • G.P. Briner et al.

    Mineralogical analysis of clays in soils developed from basalts in Australia

    Israel Journal of Chemistry

    (1970)
  • A.B. Camens et al.

    Diprotodontid footprints from the Pliocene of central Australia

    Journal of Vertebrate Paleontology

    (2009)
  • A.S. Cohen et al.

    Modern vertebrate tracks from Lake Manyara, Tanzania and their paleobiological implications

    Paleobiology

    (1993)
  • J.J. Day et al.

    Dinosaur locomotion from a new trackway

    Nature

    (2002)
  • P. Dodson

    Quantitative aspects of relative growth and sexual dimorphism in Protoceratops

    Journal of Paleontology

    (1976)
  • J.O. Farlow et al.

    Theropod locomotion

    American Zoologist

    (2000)
  • J.O. Farlow et al.

    Body form and trackway pattern in Australian desert monitors (Squamata: Varanidae): comparing zoological and ichnological diversity

    Palaios

    (2000)
  • M.E. Finch et al.

    Functional morphology of the limbs of Thylacoleo carnifex Owen (Thylacoleonidae: Marsupialia)

    Australian Journal of Zoology

    (1988)
  • R.F. Galbraith et al.

    Optical dating of single and multiple grains of quartz from Jinmium rock shelter, northern Australia: part I, experimental design and statistical models

    Archaeometry

    (1999)
  • P.M. Galton et al.

    Dinosaur State Park, Connecticut, USA: history, footprints, trackways, exhibits

    Zubia

    (2003)
  • P.A. Gell et al.

    The Holocene history of West Basin Lake, Victoria, Australia; chemical changes based on fossil biota and sediment mineralogy

    Journal of Paleolimnology

    (1994)
  • R. Grün et al.

    An alpha irradiator for ESR dating

    Ancient TL

    (1994)
  • R. Grün et al.

    Electron spin resonance dating of South Australian megafauna sites

    Australian Journal of Earth Sciences

    (2008)
  • J. Hellstrom

    Rapid and accurate U/Th dating using parallel ion-counting multicollector ICP-MS

    Journal of Analytical Atomic Spectrometry

    (2003)
  • Cited by (0)

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