Fraser, D.; Rybczynski, N.; Gilbert, M.; Dawson, M. R.

The North Atlantic Land Bridge (NALB), which connected Europe to North America, enabled high latitude dispersal, particularly during globally warm periods such as the Paleocene-Eocene Thermal Maximum, a period of dramatic faunal reorganization. It has been generally accepted that the NALB was submerged by the early Eocene. Herein, we describe a new rhinocerotid species from the early Miocene of the Canadian High Arctic with proximity to the NALB and present a novel phylogenetic hypothesis for rhinocerotids. We model a high number of dispersals between Europe and North America, some of which occurred in the Oligo-Miocene, suggesting that the NALB may have been crossable for mammals millions of years longer than previously considered. Moreover, recent geological and palaeoclimatological evidence suggest that, until the Miocene, portions of the NALB may have been separated only by narrow and shallow waterways and, potentially, bridged by seasonal sea ice as early as the late Eocene, enabling rhinocerotid dispersal. We thus provide insight into the importance of the Arctic as a persistent connector of otherwise geographically disparate faunas that played a pivotal role in mammalian evolution.