A new species of Acynodon (Crocodylia) from the Upper Cretaceous (Santonian-Campanian) of Villaggio del Pescatore, Italy

摘要

The new species Acynodon adriaticus is described on the basis of remains from the Santonian-Campanian of Villaggio del Pescatore (Trieste, NE Italy). This species differs in several cranial features from Acynodon iberoccitanus, the only other Acynodon species whose cranial osteology is known in detail. The absence of maxillary and dentary caniniform teeth coupled with the presence of enlarged molariform teeth suggests that Acynodon probably fed on slowly moving hard-shelled prey. Moreover, the new materials reveal for the first time the morphology of some postcranial elements of Acynodon: in particular, medial-most paravertebral osteoderms that are characterized by two keels. A new cladistic phylogenetic analysis resolves the previously reported polytomy among the basal Globidonta: Acynodon is recognized as the most primitive globidontan. This genus may represent the geologically oldest known globidontan. The fact that Acynodon has been found only in Europe and that the outgroup of Globidonta, the Diplocynodontinae, is mainly known from Europe, suggests that globidontans may have originated in Europe and not in North America as previously supposed.