isolated Mesoeucrocodylian tooth crown from the lower Cretaceous cerro La Isla pterosaur site in the Atacama region, northern Chile

Abstract

We describe the first crocodyliform fossil found in continental deposits from the Lower Cretaceous of the Quebrada Monardes Formation on Cerro La Isla, Atacama region, northern Chile. The material consists of a single, poorly preserved tooth crown (SGO.PV 1160), whose enamel surfaces bear tightly-packed apicobasal ridges. Our comparisons of SGO.PV 1160 with the dental morphology of possible taxa that it may belong to suggest a hitherto unknown pholidosaurid, or, more likely, notosuchian. Therefore, the tooth crown is here provisionally identified as Mesoeucrocodylia indet., pending future discoveries of more complete material. This find increases the known biodiversity in the Lower Cretaceous deposits of Cerro La Isla, as well as the importance of the fossil site, since pholidosaurids have not been reported from Chile, and if it proves to be notosuchian, it may represent the earliest known taxon of this group from South America, and the second earliest in the world.