"The theory that people have proposed is they got into South America early on, where their only competition was from insect-eating bats. So they evolved a bunch of different feeding strategies," said Gary Morgan, curator of vertebrate paleontology at the New Mexico Museum of Natural History.

A new discovery suggests the story may be more complicated. In an article published by the Journal of Mammalian Evolution, Morgan and his colleagues describe the oldest-known leaf-nosed bat fossils, which were found along the banks of the Panama Canal. They're also the oldest bat fossils from Central America, preserved 20-million years ago when Panama and the rest of North America were separated from southern landmass by a seaway at least 120 miles wide.

Based on these and other fossils, Morgan thinks previous studies may have singled out the wrong continent as the birthplace of leaf-nosed bats.

"We think they may have had a northern origin."

Once-in-a-century opportunity leads to several new discoveries

In 2007, hundreds of engineers, excavators and geologists gathered in Panama to begin the daunting task of widening and deepening the country's historic canal. Paleontologists weren't far behind. After the work crews used dynamite to blow apart sections of the bank, researchers moved in, picking out fossil fragments from the rubble. The bones held clues to one of the greatest mass migrations of animals in Earth's history, and the canal expansion marked the first time anyone had this close of a look.