NEW IDENTIFIED FOSSIL MAMMALS FROM THE SWIFT CURRENT CREEK LOCALITY, SASKATCHEWAN

The middle Eocene Swift Current Creek locality, of the Cypress Hills Formation in Saskatchewan, is among the most diverse fossil mammal localities in North America. The locality's faunal list was recently reviewed, resulting in some important discoveries. Material previously referred to as Chiroptera (Storer 1984) instead resembles the early pantolestid genus Bessoecetor, extending its known temporal range. Bessoecetor was previously known to occur in the late Paleocene deposits of the Ravenscrag Formation, and its continued survival could have been obscured by a gap in Saskatchewan’s fossil record that spans the early Eocene. A lower molar and dentary referred to as Wallia scalopidens represents an early talpid (mole) resembling Oreotalpa, suggesting an earlier first appearance in the fossil record. A brontothere P4 previously identified as Diplacodon is referred instead to?Rhinotitan, which has only been documented from middle Eocene localities in China and eastern Europe. The potential presence of Rhinotitan in North America in middle Eocene deposits, millions of years after the late Paleocene-early Eocene biotic interchange, indicates that mammalian immigration during the Paleogene period is still not fully understood.