Tyrannosaurus rex, Osborn, 1905

Osborn, H. F., 1905, Tyrannosaurus and other Cretaceous carnivorous dinosaurs, Bulletin of the American Museum of Natural History 21, pp. 259-265 : 262-263

3. From the Laramie (Edmonton) of Montana, Wyoming, and Alberta.

Tyrannosaurus rex gen. et sp. nov.

Type. — The larger portion of a skeleton from the true Laramie of Hell Creek, Dawson County, Montana, 220 feet above the Ft. Pierre, American Museum No. 973 .

Characters. — Carnivorous Dinosaurs attaining very large size. Humerus believed to be of large size and elongate (Brown). No evidence of bony dermal plates (Brown).

The parts already discovered are, both jaws and portions of the skull, vertebrae, ribs, scapula, humerus, ilium, pubis, ischium, metapodials. The association of the very large humerus with this skeleton is, according to Mr. Brown, almost certainly correct, and abundantly characterizes this animal; but in the writer’s opinion final judgment must be suspended until the skeleton is fully worked out. The jaws and skull are not as yet prepared for description, so that comparison of these parts cannot be made at present with Dynamosaurus or Albertosaurus . No dermal plates whatever were found associated with this skeleton. Mr. Brown has devoted the entire past season (1905) to the very difficult work of completing the excavation of this skeleton from the hard sandstone.

The size of the chief portions of the skeleton at present prepared from the quarry may be judged from the following table of measurements:

Pubes complete, length	1250mm.
Pubes, free portion, length	470
Left tibia, length	1118
Mts. II of right leg, length	573

When placed together, as provisionally outlined by Dr. W. D. Matthew, the enormous proportions of this animal become very evident as compared with the skeleton of a man, the total length being estimated at thirty-nine feet, the height of the skull above the ground at nineteen feet.

Beside the parts above enumerated in the table, we have prepared the supraorbital portion of the frontal bone, extremely rugose, constituting a horn above the orbit very similar to that seen in Allosaurus . The jaw is represented by the dentary, angular, and articular.

Of the six dorso-lumbar vertebrae preserved, the largest, which probably belongs to the mid-dorsal region, exhibits a shallow amphicoelous centrum measuring 270 mm. transversely, 253 mm. vertically; the height of this vertebra to the top of the spine is 630 mm.

The pubes unite 470 mm. below the articular surfaces, forming a massive bar which terminates in the huge expanded pedicle. Portions of both femora have been recovered. These bones resemble the femora of Allosaurus . The preparation of this skeleton was very largely the work of Professor R. S. Lull.

Figures

Fig. 1. Rough outline showing scale of size of Tyrannosaurus rex. By W. D. M. The association of the small forearm is probably incorrect.