Daspletosaurus cf. D. torosus, Russell, 1970

Russell, Dale A., 1970, Tyrannosaurs from the Late Cretaceous of western Canada, Ottawa: National Museum of Natural Sciences, Publications in Palaeontology, No. 1 : 18

Daspletosaurus cf. D. torosus

Distribution

Member B of Edmonton Formation, near ScoUard, Alberta.

Referred Specimen

NMC 11315 scattered cranial elements, abdominal ribs, left forelimb, pelvis and hind limbs (SW. 1/8 sec. 20, tp. 34, rge. 21, W. 4th mer., 150 feet above south bank of Red Deer River).

Comments

NMC 11315 represents the remains of a slightly more than half-grown tyrannosaur. It is referred to Daspletosaurus because the humerus, radius-ulna, ilium, and circumference of the femur are longer relative to the length of the femur than would be expected in an Albertosaurus of similar femur length. The claw of the first digit of the manus seems less recurved than in the latter genus. The specimen shows that Daspletosaurus probably underwent the same ontogenetic changes in limb proportions as did Albertosaurus . The foot is very similar to that of Albertosaurus , although the metatarsus is slightly shorter than in similarly sized specimens of this genus.

Tyrannosaur humeri are very infrequently found, and of the two Daspletosaurus specimens where it is preserved, the distal end of one (NMC 8506) is pathologic. Similarly, of five specimens of A. libratus where a humerus is preserved, in two of them (UA 10, FMNH PR308) the bone has also been damaged in life. This is an unusually high incidence of damage and suggests that the small forelimbs were often crushed by the weight of the massive bodies of these reptiles.