Immature Daspletosaurus sp. specimens from the Dinosaur Park Formation provide insight into ontogenetically invariant tyrannosaurid cranial morphology
Publication: Canadian Journal of Earth Sciences
26 November 2024
Abstract
Understanding the extent to which tyrannosaurid cranial morphology changed through ontogeny is essential to correctly refer tyrannosaurid specimens at varying life stages to taxa. However, taxonomically diagnostic immature tyrannosaurid bones remain exceedingly elusive. Over the last century, the University of Alberta has collected three isolated immature cranial bones referable to Daspletosaurus from Dinosaur Provincial Park, Alberta of Treaty 7 Territory. These bones were all collected from the rocks of the Dinosaur Park Formation and include a premaxilla (UALVP 48717), jugal (UALVP 61561), and lacrimal (UALVP 47955). To assess the taxonomic utility of these bones, they were compared to tyrannosaurid material from the Dinosaur Park and Oldman Formations of Alberta. This provided an opportunity to examine size-independent discrete characters in tyrannosaurid crania. The results of this study suggest that many premaxillary, jugal, and lacrimal discrete characteristics observed in Daspletosaurus are constrained throughout ontogeny. A single ontogenetically invariant character, the dorsal flange of the palatal process, was identified for Daspletosaurus premaxillae. Ontogenetically invariant characters of the jugal include, but are not limited to, a medial lacrimal slot and the lateral fossa on the postorbital process. Invariant lacrimal characters include an anteroposteriorly short pneumatic recess opening and a subdivided nasal articulation fossa on the medial surface of the bone. The identification of these characters allows specimens of the tyrannosaurine Daspletosaurus and the contemporaneous albertosaurine Gorgosaurus to be confidently identified regardless of ontogenetic stage. These characters were applied to a controversial tyrannosaurid specimen from the Dinosaur Park Formation, TMP 1994.143.0001, resulting in referral to Gorgosaurus libratus, rather than Daspletosaurus sp.
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Published In
Canadian Journal of Earth Sciences
Volume 61 • Number 12 • December 2024
Pages: 1227 - 1239
History
Received: 29 May 2024
Accepted: 28 August 2024
Accepted manuscript online: 11 September 2024
Version of record online: 26 November 2024
Copyright
© 2024 The Author(s). Permission for reuse (free in most cases) can be obtained from copyright.com.
Data Availability Statement
All data pertaining to this study has been provided within the article and supplementary materials. UALVP specimens described herein are housed at the University of Alberta Laboratory for Vertebrate Palaeontology in Edmonton, Alberta, Canada.
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Authors
Author Contributions
Conceptualization: CCC, PJC
Data curation: CCC
Formal analysis: CCC, MJP
Investigation: CCC, MJP, JTV, HSS
Project administration: PJC
Resources: PJC
Supervision: PJC
Writing – original draft: CCC
Writing – review & editing: MJP, JTV, HSS, PJC
Competing Interests
The authors have no competing interests to declare.
Funding Information
Dinosaur Research Institute: Student, Research, Grant
Funding for this project was provided to CCC by the Dinosaur Research Institute in the form of the Student Research Grant.
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Colton C. Coppock, Mark J. Powers, Jared T. Voris, Henry S. Sharpe, and Philip J. Currie. 2024. Immature Daspletosaurus sp. specimens from the Dinosaur Park Formation provide insight into ontogenetically invariant tyrannosaurid cranial morphology. Canadian Journal of Earth Sciences.
61(12): 1227-1239. https://doi.org/10.1139/cjes-2024-0083
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