A Late Cretaceous(Turonian-Coniacian) high-latitude turtle assemblage from the Canadian Arctic

摘要

Three turtles are present in a Turonian-Coniacian age high-latitude vertebrate assemblage from Axel Heiberg Island: Borealochelys axelheibergensis gen. et sp. nov., a generically indeterminate eucryptodire, and a trionychid. The assemblage differs from most Late Cretaceous turtle assemblages from North America in that members of the Paracryptodira are absent. The absence of this group is interpreted as a result of latitudinal differentiation of turtle assemblages in North America during the Late Cretaceous. The level of diversity of turtles in the Axel Heiberg assemblage is comparable to that of mid-latitude assemblages associated with a mean annual paleotemperature of 14 deg C, adding to the evidence for high mean annual temperatures at high latitudes during Turonian-Coniacian times.