Tyrannosauroidea - Classification

Classification

Tyrannosaurus was named by Henry Fairfield Osborn in 1905, along with the family Tyrannosauridae. The name is derived from the Ancient Greek words τυραννος/tyrannos ('tyrant') and σαυρος/sauros ('lizard'). The superfamily name Tyrannosauroidea was first published in a 1964 paper by British paleontologist Alick Walker. The suffix -oidea, commonly used in the name of animal superfamilies, is derived from the Greek ειδος/eidos ('form').

Scientists have commonly understood Tyrannosauroidea to include the tyrannosaurids and their immediate ancestors. With the advent of phylogenetic taxonomy in vertebrate paleontology, however, the clade has received several more explicit definitions. The first was by Paul Sereno in 1998, where Tyrannosauroidea was defined as a stem-based taxon including all species sharing a more recent common ancestor with Tyrannosaurus rex than with neornithean birds. To make the family more exclusive, Thomas Holtz redefined it in 2004 to include all species more closely related to Tyrannosaurus rex than to Ornithomimus velox, Deinonychus antirrhopus or Allosaurus fragilis. Sereno published a new definition in 2005, using Ornithomimus edmontonicus, Velociraptor mongoliensis and Troodon formosus as external specifiers. The Sereno definition was adopted in a 2010 review.