New paper: juvenile Gorgosaurus from the Wapiti Formation

[Thomas Richard Holtz]

Coppock, C.C., H.C.E. Larsson & P.J. Currie. in press. A juvenile specimen of Gorgosaurus libratus from the Wapiti Formation of northeastern British Columbia, Canada sheds light on the palaeoecology of Upper Campanian tyrannosaurids. Paleo3.  https://www.sciencedirect.com/science/article/abs/pii/S0031018226004700

Abstract

Tyrannosaurid dinosaurs are well represented throughout Campanian-aged rocks of southern Alberta. However, little is known about the taxonomic diversity of the clade at latitudes north of this region. A natural mold of a partial tyrannosaurid rostrum (TMRF 2017.01.01) was collected from the Wapiti Formation of the Tumbler Ridge region in British Columbia, Canada. It includes a complete right maxilla, and parts of the right lacrimal and jugal from a juvenile individual. Although the precise stratigraphic position remains uncertain due to the proximity of an orogenic belt, preliminary stratigraphic interpretations indicate that the specimen is from the Upper Campanian section of the Wapiti Formation. The well-preserved natural mold provided an opportunity to produce a highly detailed cast (UALVP 63805) that preserves minute features of the original specimen and permits taxonomic identification. The combination of cranial characteristics present in the specimen supports a referral to Gorgosaurus libratus. The preserved region of the maxilla indicates the presence of incisiform teeth occupying alveoli one and two. While immature specimens of Gorgosaurus from the Dinosaur Park Formation share this anatomy, mature specimens possess a single incisiform tooth in the first alveolus, suggesting an ontogenetic shift in feeding behavior. Although limited, the cranial material indicates little variation in morphology across the extensive biogeographic distribution of contemporaneous specimens of Gorgosaurus, which now spans from northern Montana to northeastern British Columbia. The convex hull formed by occurrences of Gorgosaurus generates in a minimum geographic range of approximately 198,000 km². Geographic ranges of extant terrestrial apex predators are much larger, indicting either the distribution of Gorgosaurus was controlled by factors not present today, its range is greatly underestimated, or a combination of both. This novel occurrence, together with additional occurrence data for Gorgosaurus and the contemporaneous tyrannosaurine Daspletosaurus, supports previous hypotheses regarding spatially disparate distributions of Laramidian tyrannosaurid taxa. These patterns elucidate the complex ecological interactions of tyrannosaurid taxa and the faunal diversity throughout Campanian ecosystems.

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Thomas R. Holtz, Jr.
Email: tho...@umd.edu         Phone: 301-405-4084
Principal Lecturer, Vertebrate Paleontology

Office: CHEM 1225B, 8051 Regents Dr., College Park MD 20742

Dept. of Geological, Environmental, and Planetary Sciences, University of Maryland
http://www.geol.umd.edu/~tholtz/

Phone: 301-405-6965
Fax: 301-314-9661              

Faculty Director, Science & Global Change Program, College Park Scholars

Office: Centreville 1216, 4243 Valley Dr., College Park MD 20742
http://www.geol.umd.edu/sgc
Fax: 301-314-9843

Mailing Address: 

                        Thomas R. Holtz, Jr.
                        Department of Geological,

                            Environmental, and Planetary Sciences
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                        8000 Regents Drive
                        University of Maryland
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[Vladimír Socha]

Good day, Dr. Holtz! I'm wondering what this new find implies in regard to your hypothesis about the pattern that indicates shared ecological preferences between tyrannosaurines, chasmosaurines and hadrosaurines in Northern Laramidia. Does the idea of Dalle Russell still hold? I mean the hypothesis that Gorgosaurus may have preyed on the abundant hadrosaurs of the time, while the more robust and less common Daspletosaurus may have specialized on the rare, but better-defended ceratopsids, which were more difficult to hunt? OTOH, there is a specimen of Daspletosaurus (OTM 200) from the Two Medicine Formation, that preserves the digested remains of a juvenile hadrosaur in its gut region... Thank you in advance, VS.

References:

Russell, Dale A. (1970). Tyrannosaurs from the Late Cretaceous of western Canada. National Museum of Natural Sciences Publications in Paleontology. 1: 1–34.

Varricchio, David J. (2001). Gut contents from a Cretaceous tyrannosaurid: implications for theropod dinosaur digestive tracts (PDF). Journal of Paleontology. 75 (2): 401–406.

Farlow, James O.; Pianka, Eric R. (2002). Body size overlap, habitat partitioning and living space requirements of terrestrial vertebrate predators: implications for the paleoecology of large theropod dinosaurs (PDF). Historical Biology. 16 (1): 21–40.

Holtz, Thomas R. (2004). "Tyrannosauroidea". In Weishampel, David B.; Dodson, Peter; Osmólska, Halszka (eds.). The Dinosauria (Second ed.). Berkeley: University of California Press. pp. 111–136.

Snively, Eric; Henderson, Donald M.; Phillips, Doug S. (2006). Fused and vaulted nasals of tyrannosaurid dinosaurs: implications for cranial strength and feeding mechanics (PDF). Acta Palaeontologica Polonica. 51 (3): 435–454.

Dne neděle 21. června 2026 v 17:26:19 UTC+2 uživatel Thomas Richard Holtz napsal:

[Thomas Richard Holtz]

Without breaking embargo, there is an interesting paper (not of my own) that will be dealing with new lines of evidence to examine food preferences among Gorgosaurus, Albertosaurus, and Daspletosaurus. Hopefully it won't be too many months before it is out.

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[Vladimír Socha]

Also, we now have a very rough estimates of maximum geographical distribution for three genera of tyrannosaurids - Tyrannosaurus, Tarbosaurus and Gorgosaurus (although in Tarbosaurus it is rather 2300 km diameter of its geographical range)...

1) Tyrannosaurus rex - 2.3 (± 0.9) million km²

2) Tarbosaurus bataar - 2.3 million km²  (or some 4 million km² according to 2300 km diameter - if close to "circular" shape - of its geographical range)

3) Gorgosaurus libratus - 0.198 million km²

References:

Marshall, C. R.; et al. (2021). Absolute abundance and preservation rate of Tyrannosaurus rex. Science. 372 (6539): 284-287. doi: 10.1126/science.abc8300

Gorm Skouboe, R.; et al. (2026). Taxonomic reassessment of juvenile tyrannosaurine specimens from Asia reveal large biogeographic ranges in tyrannosaurids. Cretaceous Research. 186 106412. doi: 10.1016/j.cretres.2026.106412

Coppock, C. C.; et al. (2026). A juvenile specimen of Gorgosaurus libratus from the Wapiti Formation of northeastern British Columbia, Canada sheds light on the palaeoecology of Upper Campanian tyrannosaurids. Palaeogeography, Palaeoclimatology, Palaeoecology. 114007. doi: https://doi.org/10.1016/j.palaeo.2026.114007

Dne úterý 23. června 2026 v 14:36:13 UTC+2 uživatel Thomas Richard Holtz napsal:

[Thomas Richard Holtz]

Note: not maximum ranges: MINIMUM ranges. We lack data for sites beyond these current ones that are definitively correlative. Furthermore, failure to find a particular fossil is not evidence of that taxon's absence: in paleobiogeography you cannot treat a "0" with the same level of certainty as a "1".

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