Abstract

Australian Agamidae are often found in Cenozoic fossil deposits, but remain largely unidentified and unpublished. Skeletal morphological characters have been proposed for specific Australian Agamidae as well as the clade in general, but not formally tested for inter- and intraspecific variation. We compared 60 morphological features (44 from the literature and 16 new characters) for three taxa of the most specious Australian agamid genus, Ctenophorus. Each species is represented by a statistically significant sample (n = 18-20). Ctenophorus caudicinctus (n = 18), Ctenophorus isolepis (n = 20), and Ctenophorus reticulatus (n = 20) all have at least one morphological feature that does not vary and is unique to that species. Invariant features are also shared between two species or all three. Seventeen morphological features were invariant for all three taxa. A correlation coefficient analysis found that one to five additional features varied with ontogeny or sex for each taxa. One to seven features were also shared between species. All-together, we found that very few proposed morphological features could be classified as apomorphic in this three taxon system and we propose even fewer could be identified from disarticulated material. Larger collections of extant agamid skeletal material are needed to understand skeletal morphological variation. Only then can morphological data contribute to the important genetic and biogeographic studies on the present and past of Australian Agamidae already underway. The fossil record of Australian Agamidae already exists, we just need to develop the tools to understand it.