Paleobiogeography

Dating the history of a biotic connection

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Science  15 May 2015:
Vol. 348, Issue 6236, pp. 769
DOI: 10.1126/science.348.6236.769-c

The land bridge connecting South and Central America may have formed millions of years earlier than thought

PHOTO: © ROBERT HARDING PICTURE LIBRARY LTD./ALAMY

The closure of the Panama isthmus enabled the dispersal of terrestrial organisms between South and Central America and prevented the dispersal of marine creatures between the Caribbean and Pacific oceans. This Great American Biotic Interchange is generally held to have begun about 3.5 million years ago. Bacon et al. analyze fossil and molecular sequencing data that indicate some significant and much earlier dispersal events for terrestrial organisms and separation events for marine organisms, at 6 to 7 and 23 to 24 million years ago. Together with recent geological evidence for earlier land emergence, these results suggest a more complex history for the biogeographic events shaping the biota of the Americas.

Proc. Natl Acad. Sci. U.S.A. 10.1073/pnas.1423853112 (2015).

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