In 1902, the American Museum expedition in Montana, led by Mr. Barnum Brown, and accompanied by Professor R. S. Lull, secured considerable portions of the skeleton of one of the great Carnivorous Dinosaurs of Upper Cretaceous or Laramie age. Additional portions of this skeleton (Amer. Mus. No. 973) are now (1905) being taken out. I propose to make this animal the type of the new genus Tyrannosaurus, in reference to its size, which greatly exceeds that of any carnivorous land animal hitherto described.
I also briefly characterize as Dynamosaurus another carnivorous dinosaur, with dermal plates, found by Mr. Brown in 1900. The carnivorous group has hitherto been considered as belonging to the single genus Dryptosaurus, but it is probably little less diversified than its herbivorous contemporaries among the Iguanodontia and Ceratopsia. The generic distinctions which are herein indicated by partially studied remains will probably be intensified by future research. Geological, geographical, and morphological considerations render it a priori probable not only that the above genera as well as Deinodon are distinct from Dryptosaurus but that a fifth Cretaceous genus of somewhat more primitive character, which may be called Albertosaurus, is represented in the British Columbia skulls hitherto described as Dryptosaurus.