Eocene Antarctica: a window into the earliest history of modern whales
Eocene Antarctica: a window into the earliest history of modern whales
at : Apr 08, 2019 16:39:33  (view:782)

Mónica R. BUONO1*, R. Ewan FORDYCE2,3, Felix G. MARX4,5,6,7, Marta S. FERNÁNDEZ8 & Marcelo A. REGUERO9,10

1 Instituto Patagónico de Geología y Paleontología, CCT CONICET-CENPAT, Bvd. Brown 2915, U9120ACD, Puerto Madryn, Chubut, Argentina;

2 Department of Geology, University of Otago, 360 Leith Walk, PO Box 56, Dunedin, Otago 9054, New Zealand;

3 Departments of Paleobiology and Vertebrate Zoology, National Museum of Natural History, Smithsonian Institution, Washington DC, USA;

4 Directorate of Earth and History of Life, Royal Belgian Institute of Natural Sciences, Brussels, Belgium;

5 Department of Geology, University of Liège, B18, Quartier Agora, 14 Allée du 6 Août, 4000 Liège, Belgium;

6 School of Biological Sciences, Monash University, Clayton, Australia;

7 Palaeontology, Museums Victoria, Melbourne, Australia;

8 CONICET–División Paleontología Vertebrados, Unidades de Investigación, Anexo Museo, Facultad de Ciencias Naturales y Museo, Universidad Nacional de La Plata, 60 y 122, B1900FWA, La Plata, Argentina;

9 CONICET–División Paleontología de Vertebrados, Museo de La Plata, Paseo del Bosque s/n, B1900FWA, La Plata, Argentina, CONICET;

10 Instituto Antártico Argentino (Dirección Nacional del Antártico), 25 de Mayo 1151, 1650, San Martín, Argentina

Abstract: 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 crown cetacean 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.

Keywords: Marambio (Seymour) Island, Basilosauridae, Mysticeti, evolution