美国科学60秒 SSS 2013-03-14

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　　It was thought that saltwater seas separated Central and South America millions of years ago. But a recent discovery may render that idea all wet. Because archaeologists in Panama have dug up the remains¹ of ancient alligator² relatives—which were freshwater creatures. The work is in the Journal of Vertebrate Paleontology.

　　Excavations³ at the Panama Canal have turned up many fossils. Recently, two partial skulls⁴ were found embedded⁵ in rocks that date back more than 19 million years, which makes them the oldest crocodilian fossils ever found in Central America. The skulls are from two species of the freshwater reptiles⁶ called caimans. Modern caimans are related to North American alligators⁷ but live only in South America.

　　To reach Panama, the caimans must have left South America around the beginning of the Miocene epoch⁸, when ocean separated the two continents. These freshwater animals should only have been able to cross a short expanse of saltwater. So at the time, Central and South America may have been much closer than we thought. Either that, or those caimans hitched⁹ a ride

　　Thanks for the minute for Scientific American 60 second science, I’m Sophie Bushwick.

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