EOCENE ‘GREENHOUSE EARTH’ FISH RECORDS FROM THE CANADIAN ARCTIC PROVIDE A DEEP-TIME PERSPECTIVE ON ARCTIC BIODIVERSITY AND ENVIRONMENTAL CHANGE

Eocene (ca. 50 Ma) fossils from the Canadian Arctic, including plants, invertebrates, sharks, bony fishes, reptiles, birds, and mammals, provide strong evidence for an ice-free Arctic with winters likely remaining above freezing during the ‘Greenhouse Earth’ thermal maximum interval. Field expeditions to Banks Island in the western Canadian Arctic have further expanded our knowledge of this critical juncture through recovery of shark, fish, turtle, and crocodylian specimens from what are interpreted as deltaic and nearshore low salinity marine deposits. Recent additions to the fauna include the bowfin fish Amia -- one large lateral line scale corresponds to a fish ca. 1.4 meters in total length, notably larger than the maximum size of extant Amia calva. We also recovered distinctive teeth of the teleost fish Eutrichiurides, otherwise known from lower latitude fossil sites in the USA, India, Africa, and Europe. Eutrichiurides is interpreted as an ambush predator in shallow marine settings, consistent with the inferred Eocene paleoenvironment that we sampled on Banks Islands. The Banks Island records, and the Canadian Arctic Eocene ‘Greenhouse’ biota as a whole, provide an important historical deep-time perspective that helps us to better understand, and potentially more accurately predict, the future impacts of ongoing climate change on Arctic environments and biodiversity.