A new exceptionally preserved specimen of <i>Dracaenosaurus</i> (Squamata, Lacertidae) from the Oligocene of France as revealed by micro-computed tomography

The best-preserved material of <i>Dracaenosaurus croizeti</i>, an almost complete and previously unpublished skull with a few associated postcranial bones (stylopodium, zeugopodium, and cervical vertebra), is described. The material comes from the locality of Cournon, a late Oligocene site in south-central France. Micro-computed tomography applied to this specimen revealed previously unknown internal osteological characters. Among lacertids, this taxon represents a notable phenomenon: it is an extreme durophagous specialist. Many of the newly observed cranial character states reflect the lifestyle of this lizard, because animals with a hard-shelled diet display a specialized cranial morphology associated with more massive cranial muscles. One unique character for Lacertidae is observed: the parietal-supraoccipital contact is formed by a ventrally deep parietal crest that fits into a bifurcate ascending process of the supraoccipital. In fact, such a connection represents the opposite to the connection in modern members of Lacertidae. Phylogenetic analysis recovered <i>Dracaenosaurus</i> inside Gallotiinae, a clade that would consist of the mainly Oligocene genera <i>Pseudeumeces</i> and <i>Dracaenosaurus</i>, the Miocene genus <i>Janosikia</i>, and the extant <i>Psammodromus</i> and <i>Gallotia</i>. Our study supports previous phylogenetic results and provides an example of the achievement of large size in mainland members of the stem of <i>Gallotia</i>, previously exemplified by <i>Janosikia</i> and <i>Pseudeumeces</i>. The extreme amblyodonty of <i>Dracaenosaurus</i> also confirms the view that herbivory in <i>Gallotia</i> is derived and may be the result of insularity. SUPPLEMENTAL DATA—Supplemental materials are available for this article for free at www.tandfonline.com/UJVP Citation for this article: Čerňanský, A., A. Bolet, J. Müller, J.-C. Rage, M. Augé, and A. Herrel. 2017. A new exceptionally preserved specimen of <i>Dracaenosaurus</i> (Squamata, Lacertidae) from the Oligocene of France as revealed by micro-computed tomography. Journal of Vertebrate Paleontology. DOI: 10.1080/02724634.2017.1384738.