The oldest "toothed" baleen whale (Mysticeti: Aetiocetidae) in the Northern Hemisphere

• Main Authors: Tsai, C-H, Goedert, JL, Boessenecker, RW
• Format: Other/Unknown Material
• Language: unknown
• Published: Zenodo 2023
• Subjects: Antarc*; Antarctic; Antarctica; baleen whale; baleen whales
• Online Access: https://doi.org/10.5281/zenodo.8105004

The origin and early evolution of baleen whales (Mysticeti, the largest extant vertebrates) have been linked to the inception of the Antarctic Circumpolar Current (ACC) at the Eocene-Oligocene boundary, and the only described Eocene mysticetes were found in the Southern Hemisphere (Antarctica, Peru), supporting this hypothesis. Here we describe a new mysticete, Fucaia humilis sp. nov., from strata in Washington State, USA, spanning the Eocene/Oligocene transition and corroborating a previously suspected early evolution of mysticetes in the Northern Hemisphere. Our results suggest a much earlier phase of mysticete radiation (>34 million years ago) across the globe during the Eocene. We hypothesize the origin and development of a relatively stable, nutrient-rich kelp ecosystem in the Eocene/Oligocene may have fostered the radiation of toothed mysticetes in the North Pacific basin.