A new neosuchian crocodyliform from the Lower Cretaceous (Aptian–Albian) Holly Creek Formation of southwest Arkansas and its implications on the relationships of Goniopholididae

A new species of neosuchian crocodyliform, Paarthurnax holliensis gen. et sp. nov., is herein described based on a nearly complete skull from the Lower Cretaceous (Aptian–Albian) Holly Creek Formation of southwest Arkansas. This locality contains a wide array of semiaquatic, aquatic, and terrestrial vertebrate body and trace fossils. This new taxon is notable for having a ventrally offset premaxillary tooth row, maxillary groove, transverse interorbital crest, elongate anterolateral process of the postorbital, transversely flattened postorbital bar, large sub-rectangular transverse ellipsoid supratemporal fenestrae, and a laterally opened cranioquadrate passage. Its overall morphology is similar to that of the putative goniopholidid Denazinosuchus kirtlandicus from the Campanian Kirtland Formation of New Mexico, though unlike D. kirtlandicus the new form bears a palatal premaxilla-maxilla suture posteromedially directed on its lateral half and anteromedially directed along its medial region, a more tapered anterior projection of the frontal, and transverse sub-rectangular supratemporal fenestrae. It shares features typically associated with goniopholidids, such as a transverse interorbital crest and a perinarial crest. However, it also shares anterior and posterior rami of jugal comparable in depth, a rod-shaped jugal, and a frontal separated medially from the orbital margin with paluxysuchids. Phylogenetic analyses recover Paarthurnax holliensis as sister to D. kirtlandicus, both falling out as derived goniopholidids. Intriguingly, paluxysuchids are recovered in a derived position within Goniopholididae. This tree topology challenges long-held assumptions about the status and distribution of Goniopholididae, which may have a more expansive distribution in the Cretaceous of North America than previously believed.