THE FIRST MAJOR VERTEBRATE FOSSIL FROM THE PLIOCENE OF ICELAND: AN ODONTOCETE (CETACEA: ODONTOCETI) FROM THE TJORNES FORMATION

Toothed whales (Cetacea: Odontoceti) are a disparate and species-rich group. Despite their modern diversity and cosmopolitan distribution, including ranges that extend into the northernmost Atlantic Ocean, their fossil record in the North Atlantic region is largely enigmatic. Field exploration of the early Pliocene Tjörnes Formation in northeastern Iceland revealed the partial skull and some postcrania of an undescribed odontocete. The Tjörnes formation includes near-shore and terrestrial deposits that alternate with lava flows. A new age model for the outcrops was recently determined using biostratigraphy of dinoflagellate cysts and paleomagnetic analyses, constraining the beds to 5-4 million years old. The fossil discovery is important both in terms of exploring the evolutionary history and biogeography of cetaceans in the North Atlantic, and the fossil record of Iceland itself. The specimen represents the northernmost occurrence of a Pliocene odontocete, bringing the fossil record into closer agreement with modern distributions. As a volcanic island, fossiliferous strata containing vertebrates are uncommon in Iceland, thus this specimen represents both a unique discovery and an opportunity to contribute to our understanding of the former biodiversity of the North Atlantic. In addition, this is the first major fossil vertebrate from the Pliocene of Iceland, and implies promise for the discovery of a more extensive fauna in the region.