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Australian blue tongue lizard ancestor was round-in-the-tooth
Carnivora profile: Egernia gillespieae

Australian blue tongue lizard ancestor was round-in-the-tooth

Date: May 1, 2019
Source: Flinders University

[Image: Egernia_gillespieae-novataxa_2019-Thorn_...et_Lee.jpg]

Reconstruction of the most complete fossil lizard found in Australia, a 15 million year old relative of our modern blue tongues and social skinks named Egernia gillespieae, reveals the creature was equipped with a robust crushing jaw and was remarkably similar to modern lizards.
A new study lead by Flinders University PHD student Kailah Thorn, published in the journal of Vertebrate Palaeontology, combined the anatomy of of living fossils with DNA data to put a time scale on the family tree of Australia's 'social skinks'.
"This creature looked like something in-between a tree skink and a bluetongue lizard. It would have been about 25 cm long, and unlike any of the living species it was equipped with robust crushing jaws," says Ms Thorn.
The results show that our Australia's bluetongue lizards split from Egernia as early as 25 million years ago.
"The new fossil is unusually well-preserved, with much of the skull, and some limb bones, all from a single individual. It belongs to the genus Egernia, a modern species in this group which are often called 'social skinks' and are known for living in family groups, sharing rocky outcrops and hollow tree stumps."
Remarkably similar to modern social skinks, E. gillespieae instead is equipped with rounded crushing teeth and a deep, thick jaw.
The fossils are from the Riversleigh World Heritage fossil deposits in northwest Queensland, and were named after Dr Anna Gillespie, a UNSW palaeontologist responsible for preparing many of the spectacular fossils from that area.
"I have been preparing the Riversleigh fossil material for quite a few years now and lizard bones are rare elements. When the jaw appeared and was quickly followed by associated skull elements, I had a good feeling it would be a significant addition to the Riversleigh reptile story," says Dr Gillespie.

Story Source:
 Flinders University. "Australian blue tongue lizard ancestor was round-in-the-tooth." ScienceDaily. (accessed May 2, 2019).

Journal Reference:
  1. Kailah M. Thorn, Mark N. Hutchinson, Michael Archer, Michael S. Y. Lee. A new scincid lizard from the Miocene of Northern Australia, and the evolutionary history of social skinks (Scincidae: Egerniinae). Journal of Vertebrate Paleontology, 2019; e1577873 DOI: 10.1080/02724634.2019.1577873
The Egerniinae (formerly the Egernia group) is a morphologically diverse clade of skinks comprising 61 extant species from eight genera, spread across Australia, New Guinea, and the Solomon Islands. The relatively large size and robustness of many egerniines has meant that they fossilize more readily than other Australian skinks and have been more frequently recorded from paleontological excavations. The Riversleigh World Heritage Area of northeastern Australia has yielded multiple egerniine fossils, but most are isolated jaw elements, and only one taxon (‘Tiliqua’ pusilla) has been formally described. Articulated remains recently recovered from the mid-Miocene AL90 site (14.8 Ma) at Riversleigh are here described as Egernia gillespieae and represent the first opportunity to describe the morphology of a significant portion of a single individual of a fossil member of the Egerniinae. We include this fossil and ‘T.’ pusilla in an integrated analysis of morphology and published molecular data to assess their relationships and to provide calibration points for the timing of the egerniine radiation. Our calibrated tree combining molecular and morphological data suggests that the modern Australian radiation dates to the end of the Eocene (34.1 Ma). Both fossils are within the Australian crown clade Egerniinae: Egernia gillespieae is placed close to species of the living genus Egernia, whereas ‘Tiliqua’ pusilla likely sits basal to the divergence of the clade inclusive of Tiliqua and Cyclodomorphus. The fossils thus provide direct evidence that the Australian radiation of the Egerniinae was well underway by the mid-Miocene.
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