The Northern Crocodile: first report of Borealosuchus (Eusuchia; Crocodylia) from Saskatchewan's lower Ravenscrag Formation (earliest Paleocene) with implications for biogeography

Abstract

Two specimens of Borealosuchus collected from the lower facies of the Ravenscrag Formation (earliest Paleocene) in southern Saskatchewan are described. One largely complete individual featuring a partial skull, mandible, and postcrania can be unambiguously assigned to Borealosuchus griffithi Wu et al. 2001 a. The other specimen consisting of skull and partial postcranial fragments is referred to Borealosuchus sternbergii Gilmore, 1910 based on diagnostic cranial features. These specimens confirm the earliest occurrence of this clade in the province of Saskatchewan and expand the known stratigraphic and geographic range of their respective species. The discovery of Borealosuchus griffithi and Borealosuchus sternbergii in proximity to each other within the same deposits suggests temporal and spatial range overlap in the Big Muddy area during the earliest Paleocene, hinting at possible niche partitioning or other ecological relationships between members of the same genus.