Creature Feature 4

This week I wanted to look at a less famous dinosaur from Hell Creek - the ornithopod Thescelosaurus.

There are actually three separate species of Thescelosaurus that are currently accepted as valid - the type species (I can explain what this means later if anyone is interested) T. neglectus, as well as T. garbanii and T. assiniboiensis. Of these three, remains of the former two have been found in the Hell Creek formation.

Thescelosaurus was a robust, bipedal dinosaur that was most likely herbivorous (Norman et al., 2004). The position of the teeth in the skull (very far from the external surface) as well as a distinct ridge on both dentaries (lower jaw bone) is believed to indicate the presence of muscular cheeks (Morris, 1976). The forelimbs had 5 fingers, and each hindlimb had four toes ending in hoof-like claws. There were also a series of ossified tendons bracing the tail from the middle to the tip, which would reduce its flexbility (Gilmore, 1915).

It was small compared to some of the other non-avian dinosaurs from the Hell Creek formation - for various specimens the length has been estimated to be between 2.5 and 4 meters (8.2 to 13.1 feet) (Galton, 1974) and a weight of approximately 200-300 kilograms (450-660 pounds) (Erickson, 2003). The type specimen of T. garbanii was estimated to be between 4 and 4.5 meters (13.1 to 14.8 feet) long (Morris, 1976).

The relative completeness of known Thescelosaurus specimens has been interpreted as evidence of a preference for channel and floodplain habitats (Lyson and Longrich, 2011). It was most likely a browser, selectively feeding on vegetation in the first meter or so up from the ground (Norman et al., 2004). Its hindlimb anatomy combined with its robust build indicates it probably was not a swift runner - the femur was longer than the tibia, unlike what is observed in fast-moving animals (Sternberg, 1940).

I hope this has given you some new information about the interesting Thescelosaurus!

Acknowledgements:
Norman, David B.; Sues, Hans-Dieter; Witmer, Larry M.; Coria, Rodolfo A. 2004. Basal Ornithopoda. In Wieshampel, David B.; Dodson, Peter; and Osmólska, Halszka (eds.). The Dinosauria (2nd ed.). Berkeley: University of California Press. pp. 393-412.

Morris, William J. 1976. Hypsilophodont dinosaurs: a new species and comments on their systematics. In Churcher, C.S. (ed.). Athlon. Toronto: Royal Ontario Museum. pp 93-113.

Gilmore, Charles W. 1915. Osteology of Thescelosaurus, an ornithopodus dinosaur from the Lance Formation of Wyoming (pdf). Proceedings of the U.S. National Museum 49 (2127): 591-616.

Galton, Peter M. 1974. Notes on Thescelosaurus, a conservative ornithopod dinosaur from the Upper Cretaceous of North America, with comments on ornithopod classification. Journal of Paleontology 48 (5): 1048-1067.

Erickson, Bruce R. 2003. Dinosaurs of the Science Museum of Minnesota. St. Paul, Minnesota: The Science Museum of Minnesota. p. 31.


Lyson, Tyler R.; Longrich, Nicholas R. 2011. Spatial niche partitioning in dinosaurs from the latest Cretaceous (Maastrichtian) of North America. Proceedings of the Royal Society B 278 (1709):
1158-1164.

Sternberg, Charles M. 1940. Thescelosaurus edmontonensis, n. sp., and classification of the Hypsilophodontidae. Journal of Paleontology 14 (5): 481-494.