A new patagonian species of Cricosaurus (Crocodyliformes, Thalattosuchia): first evidence of Cricosaurus in Middle?Upper Tithonian lithographic limestone from Gondwana

HERRERA, Y.; GASPARINI, Z.; FERNÁNDEZ, M.

PALAEONTOLOGY

WILEY-BLACKWELL PUBLISHING, INC

Lugar: Londres; Año: 2013 p. 663 - 678

0031-0239

Upper Jurassic (Tithonian) deposits in north-wes- tern Patagonia, Argentina, have yielded rich and taxonomi- cally diverse assemblages of marine reptiles. These assemblages are also remarkable by their quality of preservation and are represented by ichthyosaurs, plesiosaurs, turtles and crocodyli- forms. Despite the abundant crocodyliform record, only two metriorhynchid taxa have been identified: Cricosaurus arau- canensis and Dakosaurus andiniensis. Here we described a new species of Cricosaurus, which represents the second species of Cricosaurus in the Tithonian of the Neuque ´n Basin, and the first metriorhynchid found in lithographic limestone from Gondwana. Furthermore, this specimen has the most com- plete postcranial remains of any metriorhynchid from South America. The new species is characterized by a short distance between the premaxilla and the nasal, a relatively narrow in- terorbital width, 23?25 mandibular teeth, bicarinated teeth with fine apicobasally aligned ridges, interalveolar spaces between the first seven teeth approximately 1.5 times longer than the anteroposterior diameter of the respective alveoli. To test the assignment of the new species to Cricosaurus, we car- ried out two phylogenetic analyses. In both analyses, Cricosau- rus lithographicus sp. nov. is nested with other species referred to this genus. This new species has peculiar enamel ornamen- tation, characterized by numerous, fine apicobasally aligned ridges, when compared to other species of the genus.