The systematics of Late Jurassic tyrannosauroid theropods from Europe and North America

Abstract

Recent discoveries of more than ten new species of tyrannosauroid theropods are helping to understand the origin and evolu− tion of colossal body size and other characteristic features of Tyrannosaurus rex and its terminal Cretaceous relatives. Partic− ularly important has been the discovery and reinterpretation of Late Jurassic tyrannosauroids from Europe and North Amer− ica, which are intermediate in size and phylogenetic position between small basal tyrannosauroids and the largest Late Cre− taceous species. The fragmentary nature of these Jurassic specimens, however, has frustrated attempts to understand their systematics and phylogeny. A new specimen from the Late Jurassic of England was recently named as a new species (Stokesosaurus langhami) of the genus Stokesosaurus, which is known from several fragmentary fossils from North Amer− ica. We review the systematics and phylogeny of these European and North American specimens and show that there are no unequivocal synapomorphies uniting them. Furthermore, a revised phylogenetic analysis does not recover them as sister taxa. This necessitates a taxonomic revision of this material, and we name a new genus (Juratyrant) for theBritish specimen