Towards the end of the summer, I had the opportunity to continue fieldwork at two multitaxic Edmontosaurus quarries within the Uppermost Cretaceous Frenchman Formation in the East Block of Grasslands National Park in southern Saskatchewan under the supervision of Dr. Emily Bamforth of the Philip J. Currie Dinosaur Museum and Dr. Ryan McKellar of the Royal Saskatchewan Museum. These excavations have been ongoing and have yielded some fantastic fossil specimens and interesting geology.

One of the coolest fossils we collected this past season was a limb bone from one of our Edmontosaurus quarries, named the Leo Edmontosaurus quarry. This bone was a Cretaceous chew toy, as evidenced by well-defined tooth traces. During the excavation, a shed tooth from a Tyrannosaurus rex was collected from the same depositional layer as the bones. This association of tooth traces on Edmontosaurus bones and T. rex teeth suggests that Leo was scavenged during subaerial exposure on a floodplain near a point bar of a meandering river system. Limb bones have a high likelihood of being consumed due to large locomotor muscles being present (a great food source for predators like T. rex), and thus will tend to have more tooth traces on the bone.

The point bar deposit contains the second quarry that is being excavated, named the Clifford Edmontosaurus quarry. While this Edmontosaurus has yet to produce elements with tooth traces, teeth from T. rex and the crocodyliform Borealosuchus have shown up this past season. Adding to the mystery of this quarry, several articulated turtle skeletons have been collected from this deposit, showing no evidence of being scavenged.

Further excavation of the quarries is required, and research into the taphonomy of these two Edmontosaurus quarries is ongoing, but there are sure to be some exciting discoveries to be made in future field seasons!

Written by Jack Milligan