Pygopus (Squamata: Pygopodidae) from Mid-Holocene Cave Deposits, Western and South Australia

Pygopus (Squamata: Pygopodidae) from Mid-Holocene Cave Deposits, Western and South Australia

DOI: 10.18195/issn.0312-3162.25(1).2008.087-093 J?ecords 01 the Western Australian t'vll1sclIJJ1 25: 1-\7-93 (2001-\). Pygopus (Squamata: Pygopodidae) from mid-Holocene cave deposits, Western and South Australia 2 3 J Jim I. MeadIJ', Marci HolIenshead . , Sandra L Swift ', Christopher J. BelP and Alexander Baynes' '!Jepartment of Ccology, Northern Arizona University, Flagstaff, Arizona 1-\6011 USA; E-mail: james.Mead(onau.edu; "Departmcnt of Biological Sciences, Northern Arizona Universitv, Flagstaff, Arizona 1-\6011 USA. 'l,aboratory of Quaternarv Paleontology, Center for Environmental Sciences and Education, Northern Arizona University, Flagstaff, Arizona 1-\6011 USA. 'Department of Ceological Sciences, The jackson School of Ceoscicnccs, University of Texas at Austin, Austin, Tcxas 71-\712 USA. -'Department of Earth and Planetary Scicncl's, Wesll'rn Australian Museum, Locked Bag 49, Welshpool DC, WA 691-\6 Australia. Present address: Dcpartment of Ceosciences, East Tennessee State University, johnson City, Tennessee 37614 USA. E-mail: mead(uetsu.edu Abstract - We report fossil remains of pygopodid lizards of known or probable Ilolocenc deposits in Webbs Cave in Western Australia and Wombat Cave in South Australia. Knowledge of patterns of skeletal variation within and across pygopodid groups is insufficiently mature to permit species-level resolution. Confident identification of apomorphies to diagnose our specimens is limited by a general paucity of skeletal preparations of pygopodids. Preserved anatomical features on the fossils are interpreted in the context of published literature and putative apomorphies, and permit referral to the genus Pvgoplls. These specimens represent important additional records of Pvgopus, and contribute to an improved understanding of the evolution of faunal communities in the Holocene of western and southern Australia. INTRODUCTION northeast (Shea 1993). Al though today they are Several cave deposits in Western Australia were widespread throughout most of the continent, their excavated since the 1950s for late Quaternary fossil record is extremely sparse, with only one mammalian and archaeological remains, and known fossil from the Miocene of Riversleigh, produced a rich palaeontological record (Lundelius northwestern Queensland (Hutchinson 1997). 1960; Dortch 1996, 2(04). Marsupials and rodents Estimates of divergence times and mode of were the focus of many of these studies, and evolution and dispersal for the group are based extinctions and changes in their relative abundances mostly on inference from molecular data sets and through time are well documented. These changes tree topologies (e.g. Jennings et a1. 2(03). serve as climatic proxies or to document Although superficially snake-like in appearance, zoogeographic range variations (Lundelius 1960, pygopods retain a pectoral girdle with no external 1983; Balme et al. 1978; Baynes 1982). Squamate vestiges of front limbs and a pelvic girdle remains from these deposits also are abundant but occasionally with hind limb remnants (Creer 1989; have yet to be systematicallv studied in detail. Here Shea 1993). Based on a sequence of molecular data we report the occurrence of pygopodid lizard (125 rRNA and c-m(5) Donne1lan et a1. (1999) remains recovered from cave deposits at Webbs and support the concept that Pygopodidae and Wombat caves (J-Iampton Tableland). Diplodactylidae are sister taxa. Similarlv, the most Pygopods (flap-footed lizards) are a family of recent taxonomic treatments recognize a gekkonoid lizards endemic to Australia and New monophyletic Pygopodidae as sister taxon to Cuinea (Shea 1993). Over 38 species are currently Diplodactylidae (l\ussell and HilLler 2002) or as recognized within the family, and are classified in sister to the padless Australian carphodactylines seven genera (Apra5ia, Delma, LiaJi5, (Flan et a1. 20(4). 1lmvever, details of cranial OphidioCt,'phaI1l5, Parade1ma, [,Ietholax, and osteology and myology are presently ambiguous in PygopII5; Jennings et a1. 2003; Han et al. 2004; supporting a definitive sister-taxon relationship Maryan et al. 2(07). Pygopods occur throughout between pygopods and other groups of gekkonoids most of Australia except for Tasmania, extreme (e.g. Kluge ]987; Estes et a1. 1988; Ri)11 and Henkel southeastern Australia, and the rainforests of the 2(02). The historical uncertainty of higher-level 88 J.I. Mead, M. Hollenshead, S.L. Swift, CJ. Bell, A. Baynes relationships of pygopods contributed to a variable taxonomy for the pygopods and diplodactyline Indian geckos (see differing views in Klllge 1987; Bauer Ocean 1990; King and Mengden 1990; Hutchinson 1997). 15 - CAVE DEPOSITS 20 - Webbs Cave Western -;!" Webbs Cave (6N 132; Western Australia; Figure Australia -_~~_....-.- 1) is situated on the Hampton Tableland south of South Australia the Nullarbor Plain at 31°46'S, 127°48'E, 25"- approximately 9.5 km north of MlIndrabilla homestead. The entrance is an open, shallow sinkhole with abundant skeletal remains under 30 ,,..... overhangs. Passages go to small chambers with bones and speleothems; these chambers are \ \ \ \ ultimately terminated by roof collapse (Lundelius 35 110 115 120' 125" 1963; E. L. Lundelius field notes, May 1964; Vertebrate Paleontology Laboratory, Texas Natural Figure 1 Map of Western Australia and adjacent Science Center, The University of Texas at Austin). regions showing the locations of Webbs and Sixteen species of fossil mammals were recorded Wombat caves from which mid-Holocene from the cave by Baynes (1987). Pygopus sp. lizard remains were collected. On top of a large collapse-boulder in the entrance Heavy line represents the coastline position during the full glacial low-stand sea level sinkhole are many years of bone and sediment (adapted from Dortch 1996). accumulation, and it is here that E. L. Lundelius recovered a Sarcophilus (Tasmanian devil) premolar in 1955 and conducted excavations in basal edges of the debris cones are buried by 1964. Bulk samples of bones and sediments were reddish-brown silt of unknown age. The reddish- removed from five depth intervals. These were brown silt continues to a depth of about 92 cm originally recorded in inches as 0-3, 3-6, 6-9, 9-12, (originally determined as 36 inches). Lasiorhinus and 12-15 inches below surface but are here treated latifrons (southern hairy-nosed wombat) dug as their metric equivalents of 0-7.5, 7.5-15.0, 15.0- extensively into this silt layer. Abruptly below the 23.0, 23.0-30.5, 30.5-38.0 cm, respectively. All reddish-brown silt is a brighter red sand and clay sieved residue, charcoal, and bones are curated at unit (that shows no sign of wombat burrowing or the Texas Memorial Museum, Vertebrate bioturbation) containing limestone boulders and Paleontology Laboratory, The University of Texas skeletal remains (E. L. Lundelius field notes, May at Austin (TMM). 1964). Lizard remains, including one pygopod The principal agents of bone accumulation in the specimen, were recovered from 92-106 cm below Nullarbor and Hampton Tableland caves were Tyto surface, in the lower red sand and clay unit. The alba, T. novaehollandiae (masked owl) and Falm pygopod specimen from this lower unit is clearly cenchroides (Australian kestrel; Baynes 1987). not modern based on stratigraphic placement. The Lizard remains were common throughout the actual age is not known but is presumed to be from Webbs Cave sedimentary deposit. Two pygopod the Holocene, if not late Pleistocene. Clearly more dentaries were recovered from the 15.0-23.0 cm and work is needed in this cave. All fossils recovered by 30.5-38.0 cm intervals. Charcoal from the 15.0-23.0 E. L. Lundelius in 1964 are curated in TMM. cm interval produced an AMS radiocarbon intercept age of Cal BP 4,160 (Beta-214963), and Pygopod remains represents a mid-Holocene record. With an Relatively few publications specifically address assumption of a constant deposition rate, the the osteology of pygopodid lizards. General aspects skeletal remains in the undated 30.5-38.0 cm of skeletal morphology were discussed by Camp interval would be approximately 5,200 years old. (1923; Lialis; Pygopus), Stokely (1947; Aprasia), Parker (1956; Aprasia), Underwood (1957; Aprasia, Wombat Cave Delma, Lialis, Pygopus) and Moffat (1973; Aprasia, Wombat Cave (5N 264) is located approximately Delma, Lialis, Pletholax, Pygopus). Pectoral and 42 km west of Koonalda on the Hampton Tableland pelvic girdle morphology were discussed by in western-most South Australia (Figure 1). This Fiirbringer (1870; Lialis, Pygopus), Cope (1892; small cavern has a low arched roof and three Pygopus) and Stephenson (1962; Aprasia, Delma, entrances, each with an associated debris cone. The Lialis, Pletholax, Pygopus). General features of the Mid-Holocene Pygopods from Caves 89 skull were noted by Kinghorn (1926) and Bellairs Webbs Cave and Kamal (1981); more extensive coverage of One right dentary (TMM 41209-964; 15.0-23.0 cm particular taxa was provided by Jensen (1901; interval) and one left dentary (TMM 41209-965; Aprasia), Kinghorn (1923; Aprasia), Broom (1935; 30.5-38.0 cm interval) were recovered (Figure 2A, Pygopus), McDowell and Bogert (1954; Aprasia, B). Both are complete and have the same De1ma, Lia1is, Pygopus), Stephenson (1962; Aprasia, osteological features. The groove for the Meckelian Delma, Lia1is, P1etho1ax, Pygopus) and Rieppel cartilage is completely enclosed by bone (a (1984b; Aprasia, P1etho1ax, Pygopus). Detailed universal feature within gekkonoids, but also description of mandibular morphology

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