Tyrannosaurus, Osborn, 1905

Carr, T. D., 1999, Craniofacial ontogeny in Tyrannosauridae (Dinosauria, Coelurosauria), Journal of Vertebrate Paleontology 19 (3), pp. 497-520 : 499

I agree with Paul (1988) and Carpenter (1992) that Tarbosaurus

is a junior subjective synonym of Tyrannosaurus (contra Rozhdestvensky, 1965).

Both species are united by the absence of a lacrimal horn ( Carpenter, 1992), inflated descending paroccipital process, transversely-oriented occipital plate, and rostrocaudally restricted basisphenoid recess, among other features. A more detailed treatment of tyrannosaurid systematics is forthcoming.