The Paleogene South American native ungulates and the demise of the South America-Antarctica land connection (final Gondwana breakup)

REGUERO, M; GELFO, J; LÓPEZ, G; BOND, M; ABELLO, A; MARENSSI, S.; SANTILLANA, S

GLOBAL AND PLANETARY CHANGE

ELSEVIER SCIENCE BV

Lugar: Amsterdam; Año: 2014 vol. 123 p. 400 - 413

0921-8181

The biogeographic hypothesis more accepted today is that Antarctica (West Antarctica) and southern South America (Magellan region, Patagonia) were connected by a long and narrow causeway (Weddellian Isthmus) between the Antarctic Peninsula and South America during the Late Cretaceous (Campanian) through Early Paleogene allowing to terrestrial vertebrates to colonize new frontiers using this physiographical feature. Stratigraphically calibrated phylogenies including large, terrestrial native ungulates Litopterna and Astrapotheria taxa reveal long ghost lineages that extended into the Late Paleocene and provide evidence for the minimum times at which these ?native ungulates? were present on Antarctica and South America. Based on these results we estimate that the Weddellian Isthmus was functional as a land bridge until the Late Paleocene. The estimation dates the disconnection between Antarctica and South America in the Late Paleocene, and the terrestrial faunistic isolation (Simpson´s ?splendid isolation?) in South America begun in the final part of Late Paleocene (~56 Ma). This faunistic isolation is documented at least 25 Ma before the existence of deep-water circulation conditions in the Drake Passage (~30 Ma ago) based on the onset of seafloor spreading in the West Scotia Sea region.