Non-trionychid turtles from the Paleocene of Alberta, Canada

Turtle fossils of Paleocene age have been recovered from four formations in Alberta, Canada: the upper (Paleocene) part of the Scollard Formation, the upper (Paleocene) portion of the Willow Creek Formation, and the exclusively Paleocene Porcupine Hills and Paskapoo formations. At least three non-trionychid turtle taxa can be recognized. Definitely present are a generically indeterminate baenid, the macrobaenid Judithemys backmani, and the chelydrid Protochelydra zangerli. The carapace of a juvenile chelydrid could be either a juvenile of P. zangerli or a fourth, distinct taxon. The macrobaenid J. backmani and the chelydrid P. zangerli are the most abundant non-trionychid turtles from the Paleocene of Alberta. The turtles from the Paleocene of Alberta differ from those of comparable age in New Mexico, USA, and other more southern localities in the North American Western Interior in (i) the presence of macrobaenids and chelydrids and (ii) the absence of kinosternoids. These differences mirror those of the Late Cretaceous, suggesting that biogeographic patterns of non-trionychid turtle distributions that were established during the Late Cretaceous in the Western Interior continued well into the Paleocene.