Fieldwork Travelogue – A horned dinosaur graveyard

      For the last three years, I’ve had the privilege of doing fieldwork on the South Saskatchewan River in south-eastern Alberta. The River here cuts through some classic dinosaur-bearing deposits of the Belly River Group, which are Late Cretaceous in age (roughly 80-75 million years ago). These are the same deposits that are exposed about 80 km to the north-west in world-famous Dinosaur Provincial Park, where most of Canada’s best-known dinosaurs come from.

      But the deposits of the South Saskatchewan River are unique in their own way, especially in that they contain one of the largest dinosaur bonebeds in the world. The bonebed covers some 2.3 km2 and almost exclusively contains the jumbled remains of tens of thousands of individuals of the horned dinosaur Centrosaurus apertus. The bonebed was first discovered by palaeontologist Wann Langston Jr. in the late 1950s, but its full extent wasn’t realized until 1997, when a team from the Royal Tyrrell Museum of Palaeontology spent the summer more fully documenting the area. This foundational work was published only recently (Eberth et al., 2010) and garnered considerable media attention.

Canadian Museum of Nature collections technician Margaret Currie working in the Centrosaurus bonebed.

      During my time prospecting the region, I’ve stumbled across the bonebed on countless occasions. It occurs in a thick mudstone layer that is pervasive along much of the South Saskatchewan River in Alberta. It peters in and out, as you’d expect, being richer in fossil bones in some parts more than others. This year, though, we hit the mother lode: an area of about 20 x 20 m where the bonebed is easily accessible, occurs just below the surface, and where test excavations reveal a density of 20+ bones per square metre. Imagine the possibilities! Several years of good hard work promises to teach us a lot about Centrosaurus population structure, skeletal growth, and maybe even what killed such a huge herd of animals.

Research assistant Scott Rufolo consolidates a newly exposed bone in the Centrosaurus bonebed.

      But I’m excited for other reasons, too. The new site offers a great opportunity for students to cut their teeth excavating, field mapping, and jacketing fossils. I hope this might be the start of a successful field school. We can also offer interested patrons the chance to dig up dinosaurs for years to come, without having to locate a new find every time. It’s the gift that keeps on giving!

      Finding a complete, articulated skeleton is often considered the real jackpot in vertebrate palaeontology, but bonebeds—even those comprising only scattered bones—can arguably tell us a lot more about the biology of a fossil animal. I look forward to sharing the secrets of the world’s largest dinosaur bonebed in the coming years…

A newly exposed squamosal and parietal -- two of the bones that make up the cranial frill of Centrosaurus. Who could ask for more?

Posted by Jordan Mallon, Research Scientist, Canadian Museum of Nature

Literature cited:

Eberth, D. A., Brinkman, D. B., & Barkas, V. 2010. A centrosaurine mega-bonebed from the Upper Cretaceous of southern Alberta: implications for behavior and death events. In Perspectives on Horned Dinosaurs: The Royal Tyrrell Museum Ceratopsian Symposium, pp. 495-508.
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