Eocene Antarctica: a window into the earliest history of modern whales

R. EWAN FORDYCE; MARCELO REGUERO; FELIX MARX; BUONO, MÓNICA R.; MARTA S. FERNÁNDEZ

Advances in Polar Science

Polar Research Institute of China and the Chinese Arctic and Antarctic Administration.

Año: 2019 vol. 30

1674-9928

The Eocene-Oligocene Southern Ocean is thought to have played a major role in cetacean evolution. Yet, fossils from its heart ? Antarctica ? are rare, and come almost exclusively from the Eocene La Meseta and Submeseta formations of Marambio(Seymour) Island. Here, we provide a summary and update of this crucial fossil assemblage, and discuss its relevance in the broader context of cetacean evolution. To date, Eocene specimens from Antarctica include basilosaurids, a group of archaic stem cetaceans that had already fully adapted to life in water; and the archaic toothed mysticete Llanocetus, the second oldest crowncetacean on record (ca. 34 Ma). This Eocene co-occurrence of stem and crown cetaceans is highly unusual, and otherwise only observed in Peru. Though related, at least some of the Antarctic species appear to be different from, and notably larger than their Peruvian counterparts, suggesting an early differentiation of the high latitude cetacean fauna