The phylogenetic position of the Tyrannosauridae: implications for theropod systematics

A new cladistic analysis indicates that the tyrannosaurs were derived members of the Coelurosauria, a group of otherwise small theropods. Desipte certain gross cranial similarities with the large predators of the Jurassic and Early Cretaceous, the Late Cretaceous tyrannosaurids are shown to be the sister group to ornithominids and troodontids, which share a derived condition of the metatarsus. The taxa "Carnosauria' and "Deinonychosauria' are shown to be polyphyletic, and the Late Jurassic African form Elaphrosaurus is found to be the sister taxon to Abelisauridae. Purported allosaurid-tyrannosaurid synapomorphies are seen to be largely size-related. The remaining giant tetanurine theropods were found to be progressive distant outgroups to an allosaurid-coelurosaur clade. -from Author