The tooth-bearing skeletal elements of the Italian urodeles, a comparative tool for osteological identification

Urodele osteology is characterised by simplified skulls, loss of several bones and a specific sequence of cranial and limb ossification. The relatively few studies devoted to the comparative analysis of isolated urodele bones are mostly focused on the vertebrae and occipital complexes, and to a lesser extent humeri. The tooth-bearing skeletal elements (premaxillae, maxillae, dentaries, and vomers) are strongly neglected in this respect, despite being robust and as such sometimes found as fossils. Herein, we provide for the first time a comparative study of dentigerous bones, focusing on the Italian urodeles. Thirteen of the 19 species present in Italy, representing all genera except one, were analysed, for a total of 70 dry-prepared skeletons. The morphology of dentigerous skeletal elements of Italian urodeles is described and pictured, providing diagnostic characters and dichotomous keys for the identification at the genus level in most cases, and species level in some. The diagnostic morphological characters were included in a phylogenetic analysis, the results of which demonstrate that the tooth-bearing elements can have a phylogenetic value useful for assessing the relationships of living taxa.