| A new species of Allosaurus, A. jimmadseni is described from the Salt Wash Mbr. of the Morrison Formation. This taxon is based on a spectacular, nearly complete skeleton and skull which includes an in-place furcula and a complete, articulated gastral cuirass. A review of the alpha level taxonomy of Allosaurus reveals only one other valid species, A. fragilis. Allosaurus is known only from the Late Jurassic (Kimmeridgian) of North America and Portugal. Other reported occurrences of the genus from Europe, Australia, and Africa are either referred to other theropod taxa or are nomen dubium.; The family Allosauridae is restricted to Allosaurus and Saurophaganax. A phylogenetic analysis using 16 taxa, and 112 characters retains the monophyly of the Allosauroidea, identifying two clades, the Carcharodontosauridae (Carcharodontosaurus, Acrocanthosaurus , and Giganotosaurus) and an unnamed, monophyletic, polytomy including Allosaurus, Saurophaganax, Neovenator, Monolophosaurus, Piatnitzkysaurus, Sinraptor, and Yangchuanosaurus. Cryolophosaurus is a more basal tetanuran and Szechuanoraptor is the sister taxon to the Avetheropoda.; New taxa created in this work are Allosaurus jimmadseni, Szechuanoraptor dongi (=Szechuanosaurus campi of previous workers) and Alashansaurus for the species “Chilantaisaurus ” maortuensis. |
