[N] 2006 New pachyrhinosaurus-like Ceratopsian from the Dinosaur Park Fm. Alberta
Ryan, M., Tanke, D., Brinkan, D. & Currie, P. (2006) A new pachyrhinosaurus-like Ceratopsian from the Upper Dinosaur Park Formation (Late Campanian) of Southern Alberta, Canada. JVP 26(3) Abstracts pp.117
In 2001 an almost complete, but disarticulated, adult-sized centrosaurine ceratopsid was collected from the transgressive Dinosaur Park Formation (DPF) at Dinosaur Provincial Park (DPP) near Iddesleigh, Alberta. The skull resembles new, undescribed Pachyrhinosaurus-like material from the Late Campanian Wapiti Formation of Grand Prairie, Alberta, located approximated 640 km NE of DPP. The nasal ornamentation is a large pachystotic boss, whereas the postorbital ornamentations are deeply excavated bosses. Surface features indicate that this is an old individual. Extreme pathological deformations are present in the anterior parietal bar and in many of the phalanges, possibly indicating the cause of death. A preliminary phylogenetic analysis indicates that it is the sister taxon to the clade containing Pachyrhinosaurus canadensis and the new taxon from Grande Prairie.
The specimen occurs near the top of the DPF in a stacked channel succession that cuts out the lowest coal of the 15 m thick Lethbridge Coal Zone. The specimen was deposited on a point bar in a meandering channel that experienced seasonal-to-subseasonal variations in flow regime and depth, as a result of tidal influences and/or episodic rainfall. Dates from bentonites that bracket this interval suggest an age of 75.1 Ma. Thus, it is approximately temporally equivalent to Achelousaurus from the Two Medicine Formation of Montana and indicates an evolutionary trend towards the development of nasal and postorbital bosses in Late Campanian centrosaurines. In an upsection stratigraphic context within the Dinosaur Park Formation the new centrosaurine replaces Styracosaurus and is an additional component in a significant faunal change in the upper DPF that is also marked by the first occurrence of the chasmosaurine Chasmosaurus irvinensis and the lambeosaurine Lambeosaurus magnicristatus