Albertosaurus sarcophagus, Osborn, 1905

Holtz, TR jr., 2004, Tyrannosauroidea, The Dinosauria, University of California Press, pp. 111-136 : 1

Albertosaurus sarcophagus

is known only from the lower Maastrichtian Horseshoe Canyon Formation of Alberta (Osborn 1905); no material referred to this taxon from outside this unit has yet demonstrated derived features of the species. Lambe (1904a) and Osborn (1906) described the skull, but much of the postcranial except for the cervical and caudal regions was later described under the name Albertosaurus arctunguis Parks, 1928 . The juvenile tyrannosaurid from the Horseshoe Canyon Formation referred to Daspletosaurus (a taxon otherwise unknown from the Maastrichtian) by Russell (1970a) is almost certainly a juvenile Albertosaurus . Additional material is described by Currie (2000, 2003b).

Albertosaurus is comparable to (perhaps slightly smaller than) Gorgosaurus in size. However, it is similar to Daspletosaurus and the Two Medicine tyrannosaurine in having dorsally oriented lacrimal horns. It shares with Tyrannosaurus and Tarbosaurus a caudoventrally oriented occipital region, reduced basal tubera, two or more foramina on the lateral surface of the palatine, and (with Tyrannosaurus but not Tarbosaurus ) a caudally expanded scapula and large deltopectoral crest. In Albertosaurus each basisphenoid foramen lies within a distinct fossa. The rostral margin of the postorbital suborbital prong is jagged rather than smooth in Albertosaurus , suggesting the presence of a tendinous sheet beneath the orbit homologous to the fully ossified condition found in Gorgosaurus .