Daspletosaurus horneri in Dinosaur Park Formation in Alberta

[Ben Creisler]

Ben Creisler

bcre...@gmail.com

A new paper:

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Colton C. Coppock, Mark J. Powers, Jared T. Voris & Philip J. Currie (2025)
First occurrence of Daspletosaurus horneri (Tyrannosauridae, Tyrannosaurinae) in the Dinosaur Park Formation of Dinosaur Provincial Park, Alberta (Treaty 7 Territory)
HIstorical Biology (advance online publication)
doi:https://doi.org/10.1080/08912963.2025.2532735
https://www.tandfonline.com/doi/full/10.1080/08912963.2025.2532735


The upper Campanian tyrannosaurine Daspletosaurus horneri was originally described based solely on specimens from the Two Medicine Formation of Montana, U.S.A.. Here, a taxonomic reassessment of a stratigraphically high occurrence of a Daspletosaurus specimen, CMN 350, from the Dinosaur Park Formation provides the first evidence of D. horneri within Alberta, Canada. CMN 350 was originally referred to the species D. torosus, but re-examination of the cranial morphology of this specimen revealed characteristics more similar to those of D. horneri. These characteristics include an inflated lacrimal horn that does not extend to the medial margin of the bone, a medial pneumatic recess opening of the lacrimal that is dorsoventrally tall and mediolaterally narrow, and a distinct lateral bow of the dentary. The referral of CMN 350 to D. horneri offers valuable insight into intraspecifically variable characteristics of the skull and aided in the amended species diagnosis. Furthermore, the recognition of D. horneri within the uppermost biozone of the Dinosaur Park Formation, 49 m above the underlying Oldman Formation contact, supports system-wide faunal turnover within the formation and extends the known latitudinal range of this taxon to approximately 350 km.