Two exceptionally preserved juvenile specimens of Gorgosaurus libratus (Tyrannosauridae, Albertosaurinae) provide new insight into the timing of ontogenetic changes in tyrannosaurids

Voris, Jared. T.; Zelenitsky, Darla K.; Therrien, Francois; Ridgely, Ryan C.; Currie, Philip J.; Witmer, Lawrence, M.

Two exceptionally preserved juvenile specimens of Gorgosaurus libratus (Tyrannosauridae, Albertosaurinae) provide new insight into the timing of ontogenetic changes in tyrannosaurids

dc.contributor.author	Voris, Jared. T.
dc.contributor.author	Zelenitsky, Darla K.
dc.contributor.author	Therrien, Francois
dc.contributor.author	Ridgely, Ryan C.
dc.contributor.author	Currie, Philip J.
dc.contributor.author	Witmer, Lawrence, M.
dc.date.accessioned	2023-11-01T20:17:21Z
dc.date.available	2023-11-01T20:17:21Z
dc.date.issued	0022-04-13
dc.description.abstract	Known from dozens of specimens discovered since the early 20th century, Gorgosaurus libratus has arguably contributed more than any other taxon to our understanding of the life history of tyrannosaurids. However, juvenile material for this taxon is rare. Here, we describe two small, articulated Gorgosaurus specimens (skull lengths of ca. 500 mm) that help advance our knowledge of the anatomy and ontogeny of this taxon and of tyrannosaurids in general. The new specimens exhibit hallmark juvenile tyrannosaurid features, including long, low, and narrow skulls, large circular orbits, absent or incipient cranial ornamentation, ziphodont dentition, and an overall gracile skull frame. Comparison with other Gorgosaurus specimens of various ontogenetic stages allows for an examination of the timing of morphological changes that occurred through ontogeny in this taxon relative to other tyrannosaurids. Of particular note, Gorgosaurus and the larger Tyrannosaurus rex are found to have experienced similar ontogenetic transformations at similar percent skull length relative to the large known individuals for each respective taxon but at different absolute body sizes and biological ages, occurring at a larger size and older age in Tyrannosaurus than in Gorgosaurus. These results suggest a dissociation between the timing of cranial development and body size in tyrannosaurids. Finally, the recognition of ontogenetically invariant characters in Gorgosaurus makes it possible to determine the taxonomic identity of previously misidentified specimens.
dc.description.grantingagency	Natural Sciences and Engineering Research Council (NSERC)
dc.identifier.citation	Voris, J. T., Zelenitsky, D. K., Therrien, F., Ridgely, R. C., Currie, P. J., & Witmer, L. M. (2022). Two exceptionally preserved juvenile specimens of Gorgosaurus libratus (Tyrannosauridae, Albertosaurinae) provide new insight into the timing of ontogenetic changes in tyrannosaurids. Journal of Vertebrate Paleontology, 41(6). https://doi.org/10.1080/02724634.2021.2041651
dc.identifier.doi	https://doi.org/10.1080/02724634.2021.2041651
dc.identifier.grantnumber	RGPIN/04854
dc.identifier.uri	https://hdl.handle.net/1880/117371
dc.language.iso	en	en
dc.publisher	Journal of Vertebrate Paleontology (Taylor and Francis)
dc.publisher.faculty	Science	en
dc.publisher.hasversion	acceptedVersion
dc.publisher.institution	University of Calgary	en
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dc.title	Two exceptionally preserved juvenile specimens of Gorgosaurus libratus (Tyrannosauridae, Albertosaurinae) provide new insight into the timing of ontogenetic changes in tyrannosaurids
dc.type	Article
ucalgary.scholar.level	Graduate, Faculty, Researcher