Ramon Nagesan recently published his findings after studying the oldest dinosaur bones found in western Canada. The bones studied help fill a large gap in the dinosaur fossil record. This time was a critical one, being one of the early stages of dinosaur evolution and diversification that is observed later in the Cretaceous. Read the full article or see the summary below for greater detail.
Canada’s Oldest Rocky Mountain Dinosaur Fossil
By: Ramon Nagesan
Nagesan, R.S., Campbell, J.A., Pardo, J.D., Lennie, K.I., Vavrek, M.J., & Anderson, J.S. (2019).
An Early Cretaceous (Berriasian) fossil-bearing locality from the Rocky Mountains
of Alberta, yielding the oldest dinosaur skeletal remains from western
Canada. Canadian Journal of Earth Sciences. 10.1139/cjes-2019-0166
The fossil record of dinosaurs in North America is among the best sampled in the world due to extensive deposits and ease of access. Much of that sampling effort has been focused on western North America’s badlands, where almost 150 years of collecting has made the dinosaur faunas of the Upper Jurassic and Upper Cretaceous sequences among the best represented taxonomic groups in museum collections around the world. These collections have permitted scientists to learn a great deal about dinosaur ecology, communities, anatomy, and evolution.
However, there is an approximately 20 million year sampling gap in the North American dinosaur fossil record between the Tithonian and the Albian stages (approximately 145 through 125 million years ago (Mya)). This 20 million year interval is critical because it is thought to have witnessed some of the early stages of dinosaur biodiversity evolution and diversification that is observed later in the Cretaceous. Therefore, dinosaur-bearing rocks from this interval are of particular interest to vertebrate paleontologists. In a new study published in the Canadian Journal of Earth Sciences (https://doi.org/10.1139/cjes-2019-0166), University of Michigan Museum of Zoology research specialist Ramon Nagesan and co-authors report on one such locality from the early Cretaceous Cadomin Formation in the Rocky Mountains of Alberta, Canada. This locality has yielded a multitaxic assemblage, with the most diagnostic material identified (so far) including ankylosaurian osteoderms and a turtle plastron element.
The presence dinosaur body fossils in the Canadian Rocky Mountains adds to the growing list of large-bodied Mesozoic vertebrates from the mountains and foothills of Alberta and British Columbia, which include Cretaceous dinosaurs and older dinosaur trackways, Jurassic plesiosaurs, and Triassic ichthyosaurs. The presence of dinosaur body fossils in Berriasian-aged (~135 Mya) sediments helps fill in the ~20 million year gap in the North American dinosaur fossil record. This study and others highlights the significance and potential of the mountains and other underrepresented study localities for expanding our understanding of Mesozoic faunas from western Canada.
This study was supervised by University of Michigan alumni Dr. Jason Anderson. Dr. Anderson is now a Professor in the Department of Comparative Biology & Experimental Medicine, Faculty of Veterinary
Medicine, at the University of Calgary.