Dromaeosaurus, Matthew & Brown, 1922

Currie, P. J., 1987, Theropods of the Judith River Formation of dinosaur Provincial Park, Alberta, Canada, Fourth Symposium on Mesozoic Terrestrial Ecosystems, Drumheller, Alberta: Tyrrell Museum of Paleontology, pp. 51-60 : 54

Dromaeosaurus

is a more robust animal than Saurornitholeates langstoni , and is much rarer ( Table 1 ). The lacrimal slot ( Fig. 1e ) is well developed. In both AMNH 5356 and NMC 12349 , the orbital rim is squared off and rugose, suggesting the presence of an additional bone on the orbital rim, similar to that of Troodon . If this is the case, it may be a palpebral. An examination of Dromaeosaurus teeth from Dinosaur Provincial Park suggests that more than one species was present in Judithian times (Currie, Rigby and Sloan, in preparation). It may be significant then that NMC 12349 is more robust than AMNH 5356 , and that the ridge marking the anterior limit of the supratemporal fenestra is more strongly curved. As in tyrannosaurids, the posterodorsal surfaces of the paired frontals separate on the midline for an anteromedial process of the fused parietals ( Fig. 1e ) in NMC 12349 .

Figures

FIG. 1 Theropod frontals from Dinosaur Provincial Park. (a) Troodon formosus. TMP 86.49. 10; (b) Dromicelomimus samueli, TMP 85.56.62; (c) cf. Erilcosaurus sp., NMC 12355; (d) Saurornitholestes langstoni, TMP 86. 77. 57; (e) Dromaeosaurus albertensis, NMC 12349, AMNH 5356; (f) cf. Aublysodon sp., TMP 80.16.485; (g) cf. Gorgosaurus libratus, TMP 80.16.924; (h) Daspletosaurus torosus (after Russell. 1970). (1) Caudal limit of dorsalateral exposure of the lacrimal; (2) caudal limit of orbital rim; (3) caudal limit of postorbital suture; (4) lacrimal slot; (5) Postorbital buttress. Scale= 1cm.