New ornithischian material from the Cañadon Asfalto Formation (Middle Jurassic) of Patagonia.

BECERRA, MARCOS G.; POL, DIEGO; RAUHUT, OLIVER W.M.

Capital Federal, Buenos Aires

Jornada; XXVI 2012 Jornadas Argentinas de Paleontologia de Vertebrados; 2012

Universidad Maimonides, Fundacion de Historia Natural Felix de Azara

The Cañadon Asfalto Formation yields of the most important terrestrial vertebrate faunas from the Middle Jurassic of South America, including anurans, turtles, mammals, pterosaurs, saurischian and ornithischian dinosaurs, the latters only represented by the heterodontosaurid Manidens condorensis Pol, Rauhut and Becerra. Here we describe a new ornithischian specimen from the Cañadón Asfalto Formation that is clearly distinguished from Manidens condorensis and represents a second ornithischian taxon from this unit. This material includes a nearly complete maxilla bearing a complete toothrow (only the distalmost teeth is missing), the ventral portion of the lacrimal and the anterior part of the jugal. The morphology of the crowns (eg. leaf shaped, with marginal denticles and basal cingulum) is characteristic of ornithischian dinosaurs. The teeth of the new specimen are characterized by having only a few denticles that are proportionally large, located simmetrically to the crown-apex (unlike Manidens condorensis) and with the mesial cingulum more developed than the distal. The new taxon provides evidence on the poorly known diversity of ornithischians during the Early-Middle Jurassic and therefore increases our knowledge on the diversity of small herbivorous dinosaurs from South America during that age.