Following the K-Pg mass extinction event which wiped out the non-avian dinosaurs, the swamps and floodplains of southwest Saskatchewan were populated by an assortment of small to medium sized vertebrates including turtles, crocodiles, early mammals, and a now-extinct group of semi-aquatic reptiles known as champsosaurs. During a joint research expedition near the town of Climax, Saskatchewan by the Royal Saskatchewan Museum and Carleton University in Ottawa in August 2020, an associated skeleton of a champsosaur was recovered by Jack Miligan. The champsosaur was collected in a terrestrial shale horizon around 3 m above the K-Pg boundary, from the Paleocene aged Grey Facies of the Ravenscrag Formation. The Grey Facies records a low energy, vegetated swamp environment.
This skeleton is between 35-40% complete and is comprised of several dorsal and caudal vertebrae with intact neural arches and transverse processes, incomplete bones from all four limbs including a humerus and femurs, dozens of ribs, and several elements making up the pectoral and pelvic girdles. Numerous gastralia as well as a near complete hind foot were found in-situ upon examination of the shale horizon from which the bones had eroded out of. More fieldwork is needed to try and recover cranial material to affirm an accurate taxonomic identification of this specimen.
Research into the osteology of the specimen, as well as a review of the paleoecology of the vertebrate fauna of the Ravenscrag Formation is underway and could yield new insight into biostratigraphy, and macroevolutionary trends of champsosaur species across the K-Pg boundary in Saskatchewan.
You can read more about the discovery in this Usask news article.
Written by Jack Miligan
Note: Jack recently joined the ichnofamily at Usask as an M.Sc. student! You can read more about him on his ichnoplanet profile, or follow him on ResearchGate or Twitter. –Brittany