Much of what scientists once believed about modern bats has changed, with the discovery of a pair of previously-unknown extinct species of the winged mammal. The fossils were discovered in northwestern Egypt, in an area called the Fayum Depresion.

The animals from which the fossils were formed were ancestors of a rare variety of bat, which exhibits distinctive suckers, helping the animals thrive in a highly-unusual environment. One of the fossils has been measures at 30 million years old, while the other is estimated to have been formed 37 million years ago. At this time, northern Africa was more tropical, and home to many diverse animal species.

"The habitat was probably fairly forested, and there was likely a proto-Nile River, a big river that led into the ancient Tethys Ocean," Gregg Gunnell, lead author of the study, said.

This new discovery pre-dates the known history of sucker-toed bats by up to 36 million years. The fossils were also found far from previously-discovered bat species, extending the known range of the ancient animals by 2,500 miles. In addition to the sucker-footed bats, researchers believe the ancient species of bats may have crossed into South America over Antarctica, using an ice-free bridge that froze over 26 million years ago. Once there, the animals evolved into several species, including vampire bats. Only two species of sucker-toed bats currently exist, and they are both found in Madagascar. They are Myzopoda aurita and M. schliemanni.

"They have these little adhesive pads on their thumbs and ankles that they use to cling to leaves," paleontologist Gunnell of Duke University, said in a telephone interview with Reuters.

Instead of suction, these sessile pads attach to the plant using wet adhesion, in a manner similar to that of a tree frog. As the leaves curl up, the bats are wrapped up inside the leaf. Teeth found in the fossils are nearly identical to those in the modern animals. It is not certain from the fossils if the ancient species had yet developed the characteristic suckers.

"We've assumed for a long time that they were an ancient lineage based on DNA sequence studies that have placed them close to very old groups in the bat family tree," Nancy Simmons of the American Museum of Natural History, said in a statement. Discovery of these fossils provides the first direct evidence that modern sucker-footed bats trace their direct ancestry back tens of millions of years.

Research conducted on the newly-discovered bat fossils is profiled in the online scientific journal, PLOS ONE.