New specimen of the enigmatic, Late Cretaceous crocodyliform Neuquensuchus universitas sheds light on the anatomy of the species

Abstract

Neuquensuchus universitas is an enigmatic crocodyliform known by a single, incomplete postcranial skeleton collected in the Upper Cretaceous (Santonian) Bajo de la Carpa Formation, Neuquén province, Patagonia, Argentina. Here we describe a second specimen of N. universitas that adds important features related to the neck and limb anatomy. The new specimen allows recognizing several convergent features with dinosaurs, including a roughly S-shaped neck in lateral view and extremely gracile limb bones. In addition, the anatomy of the neural arch of the available cervical and dorsal vertebrae possesses a unique combination of traits not seen in any other crocodylomorph, including a laterally concave, fan-shaped prezygodiapophyseal lamina that overlaps most of the anterior half of the base of the neural arch and centrum in lateral view and a conspicuous, horizontal prezygopostzygapophyseal lamina. The phylogenetic analysis conducted here found an unresolved position for Neuquensuchus among early branching non-mesoeucrocodylian crocodyliforms.