A new Theriosuchus-like crocodyliform from the Maastrichtian of Romania

Abstract

We describe a new, small-sized atoposaurid crocodyliform from the Upper Cretaceous (Maastrichtian) of Haţeg Basin, Romania. Aprosuchus ghirai gen. et sp. nov. is represented by a nearly complete three-dimensional skull with articulating mandibles and an associated fragmentary procoelous cervical vertebra that may have belonged to the same subadult individual. The new taxon possesses a heterodont dentition with at least four distinct tooth morphotypes including pseudocaniniform, pseudoziphodont lanceolate, ziphodont lanceolate and ‘low-crowned’ teeth. It differs from Sabresuchus sympiestodon, the other Theriosuchus-like taxon from the same stratigraphic unit, in having less enlarged fang-like teeth, a ‘w’ shaped naso-frontal articulation and extremely large palpebrals strongly fused to the orbital margin. The new taxon shares with other atoposaurids a broad oreinirostral rostrum, a vascular opening on the dorsal surface of postorbital bar, a small antorbital fenestra, a partially septated choanal groove and symmetrically developed lateral compression of maxillary teeth. Other synapomorphies of Aprosuchus are shared by a broader range of taxa including Wannchampsus and paralligatorids. The fossil record indicates that these small, highly specialized crocodylomorphs survived up to the latest Cretaceous by colonizing remote and rather complex insular ecosystems in the western Tethyan archipelago.