A Middle Jurassic heterodontosaurid dinosaur from Patagonia and the evolution of heterodontosaurids

POL, D.; RAUHUT, O.W.; BECERRA, M.

NATURWISSENSCHAFTEN

SPRINGER

Lugar: Berlin; Año: 2011 vol. 98 p. 369 - 379

0028-1042

Heterodontosauridae is a morphologically divergentgroup of dinosaurs that has recently been interpreted asone of the most basal clades of Ornithischia. Heterodontosauridremains were previously known from the Early Jurassicof southern Africa, but recent discoveries and studies havesignificantly increased the geographical and temporal range forthis clade. Here, we report a new ornithischian dinosaur fromthe Middle Jurassic Cañadón Asfalto Formation in centralPatagonia, Argentina. This new taxon, Manidens condorensisgen. et sp. nov., includes well-preserved craniomandibularand postcranial remains and represents the only diagnosticornithischian specimen yet discovered in the Jurassic ofSouth America so far. Derived features of its anatomyindicate that Manidens belongs to Heterodontosauridae, asthe sister taxon of Heterodontosaurus and other SouthAfrican heterodontosaurids. The presence of posterior dentaryteeth with high crowns but lacking extensive wear facets inManidens suggests that this form represents an intermediatestage in the development of the remarkable adaptations toherbivory described for Heterodontosaurus. The dentition ofManidens condorensis also has autapomorphies, such asasymmetrically arranged denticles in posterior teeth and amesially projected denticle in the posteriormost teeth. At anestimated total length of 60–75 cm, Manidens furthermoreconfirms the small size of basal heterodontosaurids.