OCGC Seminar - The Southern Alberta Dinosaur Project: New Perspectives on Dinosaur Evolution in the Late Cretaceous of western Canada

   
   

Dr. David Evans 

Temerty Chair in Vertebrate Palaeontology &
Deputy Head, Department of Natural History
Royal Ontario Museum

Associate Professor
Department of Ecology & Evolutionary Biology
University of Toronto

 

Thursday, April 14th
11:30 a.m.  

3120 HP 
Carleton University

 

Abstract 

The fossil dinosaur faunas of the Edmonton Group (mostly Maastrichtian) and the Dinosaur Park Formation (Late Campanian) are well-known due to intense fossil sampling. However, the older terrestrial faunas of the lower Belly River Group (middle Campanian), the Foremost and Oldman formations, as well as the Milk River Formation (Santonian). The best exposures of these units are adjacent to the Milk River, in SE Alberta. Although known to produce dinosaur fossils for over a century, these units have been comparatively poorly sampled relative to younger deposits. For the last decade, the Southern Alberta Dinosaur Project of the Royal Ontario Museum and the Cleveland Museum of Natural History has conducted a major paleontological survey of the Milk River region. The project has collected of over 5000 new dinosaur specimens and re-evaluation of key historical specimens, and resulted in the recognition of six new species of dinosaurs.

The Milk River Formation has yielded limited by exciting fossils from a globally poorly known time period. These include the remains of a new species of turtle, and the oldest dome-headed dinosaur, Acrotholus audeti. The Foremost Formation has produced limited material, with only two dinosaur taxa known from diagnostic cranial material: the basal centrosaurine Xenoceratops foremostensis and the pachycephalosaurid Colepiocephale lambei.  The Oldman Formation consists of three successive units; Our work has revealed that each of the three units hosts a distinct dinosaur fauna. The lower unit has yielded the basal centrosaurines Albertacertatops nesmoi and the recently named Wendiceratops pinhornensis. The middle unit has produced multiple skeletons Brachylophosaurus canadensis. The upper unit has produced the most diagnostic specimens, including Euoplocephalus, Daspletosaurus nov. sp., and Saurornitholestes. Ceratopsid fossils are particularly abundant, and include Centrosaurus bonebeds, as well as a new species of spike-frilled centrosaurine. The fauna of the upper unit is similar to that of Dinosaur Provincial Park, and supports the regional distribution of dinosaur faunal zones proposed previously.

This new biostratigraphic data will be used to evaluate dinosaur faunal turnover mechanisms on a high-resolution regional scale. Habitat bottlenecking caused by transgression of the Bearpaw Sea was hypothesized to have increased rates of dinosaur morphological evolution. Our new data from the regressive units of the Belly River Group suggests that evolutionary rates of ceratopsids were consistently high, and not driven by marine transgressions.