- Chubut, Argentina ( Cañadón Asphalt Formation)
- Eoabelisaurus mefi
Eoabelisaurus is a genus of theropod dinosaur from the group of Abelisauridae. So far, a single, nearly complete skeleton is known that discovered in Patagonia and was described in 2012 by paleontologists Diego Pol and Oliver Rauhut. Eoabelisaurus dates from the Middle Jurassic and is the oldest so far discovered representatives of Abelisauridae; the next oldest evidence of this group are more than 40 million years younger. The Fund thus allows a first insight into the early evolution of Abelisauriden - he shows, for example, that the to-Find all representatives of this group extreme shortening of the forelimbs began with the reduction of distal elements. Furthermore, this finding leads to a reassessment paläobiogeographischer hypotheses. While it was previously believed that only after the separation of the latter have the Abelisauriden than one limited to the southern landmasses group emerged from the northern land masses, shows the new Fund, the Abelisauriden already existed at a time when still united all land masses to the super continent Pangaea were. The absence of Abelisauriden in the northern continents could possibly point loud and Rauhut pole on a desert which separated as a geographical barrier both land masses before their breakup.
As with all Abelisauriden it was a bipedal carnivore with a deep current skull and greatly shortened forelimbs. The skeleton found is estimated to have a length of 6 to 6.5 meters. The skull is characterized as with other Abelisauriden by the curved orbit and a large infra pace Ralf Rochester ( a cranial window of the temporal region ) from. While many later Abelisauriden showed a thickened skull with a strong texturing by numerous pits and projections, the skull at Eoabelisaurus was neither thickened nor textured. The forelimbs and in particular the four-engined hands were greatly reduced. A unique feature is found at the elbow ( ulna ), the proximal end ( olecranon ) is greatly extended and accounts for 30 % of the total length of this bone.
A phylogenetic analysis of pole and Rauhut (2012 ) comes to the conclusion that Eoabelisaurus is the most primitive known member of Abelisauridae and thus stands at the base of the family tree of this group.