Tyrannosaurus rex, Osborn, 1905

Currie, Philip J., 2003, Cranial anatomy of tyrannosaurid dinosaurs from the Late Cretaceous of Alberta, Canada, Palaeontologica Polonica 48 (2), pp. 191-226 : 225

Tyrannosaurus rex .

— Tyrannosaurus rex Osborn, 1905 is now known from several well preserved specimens. Holtz (2001) listed nine autapomorphic characters for Tyrannosaurus , including the width of the snout at the back of the maxillary tooth row, the maximum postorbital skull width, the orientation of the orbits, the distal divergence of the nasal processes of the premaxillae, the packing of the premaxillary teeth, the length of vomerine−maxillary contact, jugal contribution to the margin of the antorbital fenestra, and the shape of the vomer. However, the distal divergence of the nasal processes of the premaxillae is variable in Tyrannosaurus and other tyrannosaurines, and may be in part determined by size. The length of the contact between the vomer and the maxillary palatal shelves is also probably size−related. Loosely packed premaxillary teeth are found in both Tyrannosaurus and some specimens of Daspletosaurus torosus (NMC 8506). The degree of jugal contribution to the antorbital fenestra is variable, and can even be different from one side to the other of the same skull in tyrannosaurs. Some of the remaining characters are shared with Nanotyrannus , although tooth counts distinguish the two animals.