Re-description of the cranio-mandibular anatomy of Notosuchus terrestris (Crocodyliformes, Mesoeucrocodylia) from the Upper Cretaceous of Patagonia

Abstract

Notosuchus terrestris was the first notosuchian described worldwide and the most abundant crocodyliform species in Gondwana during the Late Cretaceous. Here, the lectotype and more than 60 complete and fragmentary specimens were studied allowing the most detailed description of the cranio-mandibular anatomy of this taxon, including poorly known regions as the braincase. Thirty-fourth characters were described and confirmed by the first time for Notosuchus. Possible autapomorphies include: frontal with olfactory tract groove convex posteriorly and with well marked furrows for laterosphenoid, small premaxillary knob fits a maxillary notch in the palate adjacent to the toothrow, small bilobate trigeminal fossa with grooves for the branches the CN Vso, CN V2 and CN V3, parietal and laterosphenoid highly pneumatic, post-temporal fenestra obliterated, presence of vestigial quadratojugal spine, ascending process of quadratojugal with posterior groove, vomer lateromedially broad, incisive foramen in heart-shaped delimited by premaxillae and maxillae, and choana with narrow pterygoid septum. We propose a crista pseudo-tuberalis separating the occiput from the braincase wall, as present in some notosuchians. Contrary to previous work, the carotid foramen and the metotic foramen open within a fossa lateral to the occipital condyle, a common feature in advanced notosuchians.