New records from Banks Island expand the diversity of Eocene fishes from Canada's western Arctic Greenhouse

Eocene vertebrates from the Canadian Arctic, including sharks, bony fishes, turtles, crocodylians, birds, and mammals, have provided strong evidence for relatively warm ice-free conditions in the Arctic during the Eocene Greenhouse interval. Recent expeditions to Banks Island (Northwest Territories) in the western Arctic have recovered a relatively more marine-influenced Eocene fauna, including sand tiger sharks, bony fishes, turtle shell fragments, and a single crocodylian specimen. We report here on new additions to this fauna, including diagnostic large scales that confirm the presence of Amia in the western Arctic. One very large lateral line scale corresponds to a fish approximately 1.4 m in total length, larger than the maximum size for extant Amia calva. We also recovered approximately 100 distinctive teeth that we assign to the teleost genus Eutrichiurides, which is otherwise known from lower latitude Paleogene sites in the United States, India, Africa, and Europe. The genus is interpreted as an ambush predator in shallow marine environments, consistent with the inferred Eocene paleoenvironment of Banks Island. The presence of Eutrichiurides in the Arctic adds a distinctive new element to the Eocene Greenhouse fauna and is intriguing with respect to the biogeography and dispersal capabilities of this taxon.