Gorgosaurus libratus Lambe 1914

Holtz, T. R., 2001, The phylogeny and taxonomy of the Tyrannosauridae, Mesozoic Vertebrate Life, Bloomington: Indiana University Press, pp. 64-83 : 69

Gorgosaurus libratus Lambe 1914 :

This taxon is known from more numerous and more complete specimens than any other North American species of tyrannosaurid. The ontogeny of this species includes many parts of the growth series ( Carr 1999).It is presently only confirmed from the Late Campanian Dinosaur Park Formation of Alberta: as the isolated postcranial material from other formations referred to this taxon do not show features unique to Gorgosaurus libratus , these assignments are tentative at best. A large but incomplete tyrannosaurid skull from the Judith River, FMNH PR308, has formed the basis of many restorations of Gorgosaurus libratus ( Russell 1970, fig. 1; Paul 1988, 335; Carpenter 1992,frgs.1,2E), but lacks Gorgosaurus synapomorphies and in fact almost certainly represents a specimen of Daspletosaurus torosus ( Carr1999) .