On an isolated crocodyliform tooth with a split carina, a rare condition first time recorded in Argentina

BARRIOS, FRANCISCO; FILIPPI, LEONARDO S.; GARRIDO, ALBERTO C.; PAULINA-CARABAJAL, ARIANA; MÉNDEZ, ARIEL H.; PIPO, LAURA; CRUZADO-CABALLERO, PENÉLOPE; PREVITERA, ELENA

CABA

Jornada; I Reunión Virtual de Comunicaciones de la Asociación Paleontológica Argentina; 2020

Asociación Paleontológica Argentina

Teeth with split carina is an uncommon trait recorded in archosaurs with ziphodont dentition (laterally compressed teeth bearing serrated margins). This condition has been reported in few theropod dinosaurs (Allosaurus, tyrannosaurids, dromaeosaurids and carcharodontosaurids) and in one Triassic phytosaur. Here, we report by the first time a split serrated mesial carina in an isolated crocodyliform tooth (MAU-Pv-CO-664) from Bajo de la Carpa Formation (Santonian, Upper Cretaceous) sediments outcropping in the area of ?La Invernada-Cerro Overo? (Neuquén Province, Argentina). The specimen MAU-Pv-CO-664 corresponds only the crown tooth and lacking the enamel. The morphology of the tooth (sub-cilindrical conical crown with serrated mesial and distal carinae) resembles that observed in Peirosauridae (Notosuchia, Crocodyliformes) recorded in Patagonia. It is 20 mm tall and has a FABL of 12 mm and a BW of 7 mm respectively. The carinae bear 9-10 denticles per 5 mm. The mesial carina is single distally but splits ventrally over the 70% of the length of the tooth, into two well-marked serrated secondary carinae. There is a remaining elongate and flat (and slightly depressed) area delimited between these two sub-mesial carinae. The split carina condition seems to be caused by trauma, aberrant tooth replacement, or genetic factor, and thus paleontologists think they may have some taxonomic potential. As an adaptation to their ecological requirements the notosuchians show a variability in crown morphology teeth, althouth split carina was never reported before. New findings will help determine if teeth with split carina have taxonomical implications for this group of Crocodyliformes.