The last two decades have seen a series of major marine reptile fossil finds in the overburden at the oilsands mines owned by Suncor Energy Inc. and Syncrude Canada Ltd. And while the discoveries are nowhere near the huge number of finds in southern Alberta, paleontologists at the University of Calgary and the Royal Tyrrell Museum say that the scale of oilsands mining operations provides a unique opportunity to find fossils that would otherwise never be seen.

Starting in the mid-Cretaceous period, roughly 120 million years ago, most of what is now Alberta was covered by the Western Interior Seaway. The Seaway’s marine environment created the perfect setting for fossil development, as professor Anthony Russell of the University of Calgary explains: “You’ve got a constant rain down onto the sea floor of remains…and then sediment falls on top of those, so as time goes by you have a layer cake developing on the sea floor.”

The remains that settled in northern Alberta consist of mostly smaller invertebrates, but they also include plesiosaurs and ichthyosaurs, two now-extinct orders of marine reptile that have been found in oilsands mining operations.