Earth Sciences Unit: New Information on the Thescelosaurus

An old find with a new identity

In 1968, Albert Swanston, a technician with the Saskatchewan Museum of Natural History (now Royal Saskatchewan Museum) collected a partial skeleton of a deer-sized dinosaur from the Frenchman River Valley near Eastend, Saskatchewan.
		Albert Swanston collected and prepared many fossils in the RSM’s collection.

One would think that this would attract attention back then but it went un-noticed. For over 40 years it remained un-noticed, for the most part. The skeleton, which included parts of the back end of the skull, was easily identified as belonging to one of the most common dinosaurs of its time (Latest Cretaceous) as Thescelosaurus (THES-kel-oh-SAWR-us). Other more “famous” members of this fauna included Tyrannosaurus and Triceratops.

The original bones are currently at the RSM Fossil Research Station within the T. Rex Discovery Centre in Eastend, and are viewable in the RSM lab through the glass wall in the gallery.

In the late 1990s, researcher Peter Galton utilized the skull parts as part of a larger study on skulls of hypsilophodonts, the group that then included Thescelosaurus as well as Parksosaurus and other small herbivorous dinosaurs. Based on the skull alone this specimen from Saskatchewan’s Frenchman Formation was believed to belong to the very common Thescelosaurus neglectus. In 1997 Tim Tokaryk, RSM palaeontologist, briefly reviewed the fauna from the Frenchman Formation and noted that there appeared to be two types of thescelosaurs from at least three partial skeletons.
		Artist's reconstruction of Thescelosaurus. Artwork by Wes Long

In 2009 University of Calgary Masters student Caleb Brown finished his thesis on "Thescelosaurs and related taxa". He believed that the specimen in question from Saskatchewan was a new species. Publishing these findings would take a few years. Later in the year a co-authored paper by Clint Boyd of the University of Texas and Caleb Brown reviewed how Thescelosaurus specimens compared with each other. For decades there was no general consensus about the three basic North American genera - Thescelosaurus, Parksosaurus, and Bugenasaura.

Boyd and others reviewed almost all the material for the first time, including specimens previously known but not included in the studies. For the first time, the Saskatchewan specimen - the small deer-sized Thescelosaurus - was studied as a whole (not just the cranial elements). The authors noted that this "may represent a new species of Thescelosaurus".

Caleb Brown measures a ceratopsian or horned dinosaur Chasmosaurus specimen at the Canadian Museum of Nature.

On November 28, 2011 in the pages of the Zoological Journal of the Linnean Society (volume 163, pp. 1157-1198, Caleb Brown and others announced that this Saskatchewan specimen, RSM P1225.1, is a new species based on features of the skull and pelvis. They named it Thescelosaurus assiniboiensis (THES-kel-oh-SAWR-us ah-SIN-ni-boy-EN-sis), after the early name for where it was collected, the District of Assiniboia.

Plant-eating Thescelosaurus assiniboiensis roamed Saskatchewan 66 million years ago. Art by Peter Bond

As luck would have it, there are two places where one can view the specimen. Back in 1986 Tokaryk had made a rubber mold of the entire skeleton, not as it would have looked in life, but as it was found at the site. Unlike most dinosaur skeletons caught in 'death throes', lying on their side with their heads turned back toward the pelvis, this specimen of Thescelosaurus looked like road kill from the Cretaceous - flattened from the top, and legs splayed to each side. A fiberglass cast was placed on display as part of the then reconstructed Earth Sciences gallery in the Royal Saskatchewan Museum. The original bones are currently at the RSM Fossil Research Station within the T. Rex Discovery Centre in Eastend, and are viewable in the RSM lab through the glass wall in the gallery. The bones are posed in side view similiar to its position in life.

Partial skeleton of Thescelosaurus assiniboiensis on display in the Earth Sciences Gallery at the RSM.

This announcement of a new species based on a skeleton found over 40 years ago illustrates the importance of museum collections. Palaeontologists are constantly making discoveries not only in the field, but also within museums. We re-examine whole or partial skeletons, utilizing new technologies and methodologies, and with fresh insight. It is certain that RSM staff will continue to make new discoveries in the field as we march on in search of new fossils weathering out from hillsides. It is also certain that we will continue to make discoveries within our own collections.

Several news organizations carried the story of this new dinosaur. Click on the link below to see their articles.

CBC News
Fox News
Maclean's Magazine
The Leaderpost
The Shaunavon Standard


For more information about Caleb Brown’s work:– http://evanslab.wordpress.com/people/caleb-m-brown/
Check out the Thescelosaurus specimens palaeontologist Caleb Brown and others studied to determine this was a new species.

Want a colouring sheet of this dinosaur? Come get one at the RSM front desk or download it here.

For further information contact the Curator of Earth Sciences.

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