New Late Cretaceous macrobaenid turtle with Asian affinities from the High Canadian Arctic: Dispersal via ice-free polar routes

A new turtle, Aurorachelys gaffneyi gen. et sp. nov., is described on the basis of a carapace and plastron of late Turonian-Coniacian age from Axel Heiberg Island in the High Canadian Arctic. This turtle is a member or the Macrobaenidae, a group that is thought to have originated in Asia. It differs from all other Late Cretaceous macrobaenids in its nearly circular shell. The earliest record of macrobaenids in North America documented by this specimen, together with the earliest records of other turtle clades that presumably originated in Asia, indicates that turtle dispersal was episodic, with most first occurrences of Asian taxa in North America clustering around the Turonian. The high global temperatures of the Turonian are interpreted as facilitating this episode of dispersal of Asian turtle groups into North America. Islands and seamounts in the young, volcanically active Arctic Ocean during the Late Cretaceous may have acted as an alternative to an Alaskan intercontinental route, and may have allowed macrobaenids to enter the part of North America east of the interior continental seaway.