LOOPING THE ALASKA (VERTEBRATE) FOSSIL HIGHWAY

The art of Ray Troll inspired by the fossil record bespeaks the recognition of his own “inner fish,” and his view of nature inspired by Alaskan ecology reflects a nexus of sea and land literally as “salmon in the trees.” Alaska, by virtue of its size, its remoteness, and its complex geology remains an emerging frontier with an important record of fossil vertebrates throughout geologic time. Our work on Alaskan fossil vertebrates has introduced us to Triassic ichthyosaurs, Cretaceous dinosaurs, and marine mammals, from Hound Island in the southeast, to Denali and the North Slope, to the Alaskan Peninsula, to Kodiak, and to Unalaska in the Aleutians. Rare but diverse Late Triassic ichthyosaurs and a thalattosaur were deposited in a unique volcanic debris flow setting and transported tectonically from 10-20° N paleolatitude to its modern position as part of the Alexander Terrane. Cretaceous rocks around the state, particularly on the North Slope and in Denali National Park, Alaska Range, document the warm Cretaceous and the importance of the Bering Land Bridge in the Mesozoic. Here we present a new genus and species of desmostylian mammal, an order with unique columnar teeth and an enigmatic suite of adaptations unlike that of any other mammals, a distribution wholly confined in the North Pacific Ocean between 33 and 10 mya, and the distinction of being the only order of marine mammals to go wholly extinct long before the presence of humans. The Unalaska desmostylian bridges the phylogenetic gap between the more basal genus Cornwallius from British Columbia and the more derived genus Desmostylus of California, Japan, and from Kodiak Island and the Alaska Peninsula. The Unalaska desmostylian helps document the unique suction-feeding strategy of herbivorous desmostylians, gathering coastal plants along the shore between sea and land. A breeding population, as shown by a neonate, inhabited the Aleutians about 23 mya, living alongside the “oyster bear” Kolponomos (not a true bear), and a primitive tooth-bearing baleen whale. A basal mysticete of approximately the same age is also known from Southeast Alaska, back on the mainland, in the Yakatat Terrane.