The Paleobiology, Paleoecology, and Evolution of Thescelosauridae (Ornithischia) from Alberta, Canada

• Author / Creator

  Hudgins, Michael Naylor

• Thescelosauridae is a basal neornithischian dinosaur clade that flourished in the Cretaceous from the Aptian to the Maastrichtian. This diverse but poorly studied group of small-bodied herbivores is divided taxonomically into Orodrominae and Thescelosaurinae, and existed in Asia and North and South America. The limited extent to which thescelosaurids have been studied is due to their generalized, plesiomorphic ornithischian anatomy and their comparatively sparse fossil record, which reflects at least in part their susceptibility to post-mortem damage. Here, I describe new thescelosaurid material from the Late Cretaceous of Alberta and establish dental differences between thescelosaurids and pachycephalosaurids, another small-bodied, ornithischian group. A new partial thescelosaurid skeleton (UALVP 56885) from the Horseshoe Canyon Formation can be referred to the unusual thescelosaurine Parksosaurus warreni based on diagnostic features present in the pelvic girdle. The referral of UALVP 56885 to P. warreni allows recognition of new postcranial autapomorphies for the taxon. New thescelosaurid remains from the Dinosaur Park and Wapiti Formations can be identified as those of indeterminate orodromines and indeterminate thescelosaurines, respectively. Qualitative and quantitative analyses of in situ pachycephalosaurid and thescelosaurid teeth reveal differences between the two clades, in crown and denticle morphology, root and crown cross-sections, crown ornamentation, and wear facet patterns. Taken together, the results presented here provide fresh evidence for temporal separation between orodromines and thescelosaurines in Alberta, implying a complex pattern of thescelosaurid evolution, and suggest that the dental differences between pachycephalosaurids and thescelosaurids should facilitate identification of isolated teeth in microfossil sites and museum settings. More reliable tooth identification will in turn prove useful in testing hypotheses on the biogeography, macroevolution, paleoecology, and temporal distribution of Pachycephalosauridae and Thescelosauridae using the microfossil record.

• Subjects / Keywords

  • Paleobiology
  • Paleoecology
  • Evolution
  • Thescelosauridae
  • Ornithischia
  • Canada
  • Alberta
  • Dinosaur

• Graduation date

  Fall 2021

• Type of Item

  Thesis

• Degree

  Master of Science

• DOI

  https://doi.org/10.7939/r3-k3ax-x394

• License

  This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.