A new basal ornithopod dinosaur (Frenchman Formation, Saskatchewan, Canada), and implications for late Maastrichtian ornithischian diversity in North America
Version of Record online: 25 NOV 2011
© 2011 The Linnean Society of London
Zoological Journal of the Linnean Society
Volume 163, Issue 4, pages 1157–1198, December 2011
How to Cite
BROWN, C. M., BOYD, C. A. and RUSSELL, A. P. (2011), A new basal ornithopod dinosaur (Frenchman Formation, Saskatchewan, Canada), and implications for late Maastrichtian ornithischian diversity in North America. Zoological Journal of the Linnean Society, 163: 1157–1198. doi: 10.1111/j.1096-3642.2011.00735.x
- Issue online: 25 NOV 2011
- Version of Record online: 25 NOV 2011
- Received 5 November 2010; revised 20 January 2011; accepted for publication 24 January 2011
A small, articulated basal ornithopod skeleton from the Frenchman Formation (late Maastrichtian) of Saskatchewan (RSM P 1225.1), previously referred to the taxon Thescelosaurus, differs from both recognized species of this taxon (Thescelosaurus neglectus and Thescelosaurus garbanii). The differences are taxonomically informative and we recognize this specimen as the holotype of a new species, Thescelosaurus assiniboiensis sp. nov., diagnosed by the presence of two autapomorphies, and displaying plesiomorphic traits more similar to those of Parksosaurus, than to those of the other Thescelosaurus species. The Frenchman Formation also harbours an intriguing faunal assemblage in which Thescelosaurus represents one of the most abundant dinosaur taxa, and preserves a relatively high proportion of small (putatively juvenile and subadult) specimens of many dinosaur taxa. Further work that increases the faunal sample from this formation, and that permits quantitative comparisons with contemporary formations, will determine whether or not these differences are well supported, and will determine their ultimate palaeobiological significance. Identification of a third species of Thescelosaurus from the late Maastrichtian of North America suggests that this taxon was more diverse than previously recognized, and shows an increase in diversity from the Campanian through the late Maastrichtian, contrasting the trends seen in most other ornithischian clades.
© 2011 The Linnean Society of London, Zoological Journal of the Linnean Society, 2011, 163, 1157–1198.