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 remains of ancient alligator relatives—which were freshwater creatures. The work is in the Journal of Vertebrate Paleontology. [Alexander K. Hastings et al., Systematics and biogeography of crocodylians from the Miocene of Panama]
Excavations at the Panama Canal have turned up many fossils. Recently, two partial skulls were found embedded 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 reptiles called caimans. Modern caimans are related to North American alligators but live only in South America.
To reach Panama, the caimans must have left South America around the beginning of the Miocene epoch, 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 hitched a ride.
[The above text is a transcript of this podcast.]