Comparative skull osteology of the lacertid lizards Eremias persica and Mesalina watsonana (Sauria: Lacertidae)

The skull of two lacertid lizards of Iran including Eremias persica from Isfahan Province, Central Iranian Plateau and Mesalina watsonana from Birjand in Southern Khorasan Province, Eastern Iran, was described and compared based on seven dry skull preparations. Prominent differences included: the shape of the premaxilla and its articulation with other skull elements, the shape of the frontal (particularly the form of its processes), the number of dentary teeth, the shape of the jugal, and the position of the parietal opening. Also in E. persica, the nasals were in contact with each other whereas in M. watsonana they were separated by the nasal process of the premaxilla and anteromedial process of the frontal. Absence of pterygoid teeth in M. watsonana and extended pyriform recess in E. persica also represented further differences. Our study contributes to the baseline understanding of squamate osteology and more specifically will facilitate further studies on lacertid morphological disparity.