A new species of bat has been described based on the oldest bat skeletons ever discovered – 52-million-year-old fossils found in the Green River Formation of Wyoming in the US.
Named Icaronycteris gunnelli, the new species is known from two skeletons previously thought to belong to another group. More than 30 bat fossils have been found in the area in the past 60 years, but all have been attributed to the Icaronycteris index, which lived 50 million years ago.
The new finding supports the theory that bats diversified rapidly on different continents around this time and comes just in time for the most important date on the chiropteran (related to bats) calendar.
April 17 is International Bat Appreciation Day, started by Bat Conservation International.
52 million years ago, in a period of Earth’s history known as the Eocene, however, there were no calendars.
“Eocene bats have been known from the Green River Formation since the 1960s,” says Dr Nancy Simmons, curator-in-charge of the American Museum of Natural History’s Department of Mammalogy. “But interestingly, most specimens that have come out of that formation were identified as representing a single species, Icaronycteris index, up until about 20 years ago, when a second bat species belonging to another genus was discovered. I always suspected that there must be even more species there.”
Today, there are more than 1,460 species of bats, found in nearly every corner of the Earth, save for the poles and a few remote islands.
Bat teeth from Asia have been found that slightly edge out the Wyoming fossil in age, but the newly described fossils – the second of which was uncovered in 1994 – are the oldest bat skeletons ever found.
However, the bats found at Green River are not the most primitive in the world, suggesting that the Eocene bats of Wyoming evolved separately from their cousins on other continents.
“This is a step forward in understanding what happened in terms of evolution and diversity back in the early days of bats,” Simmons comments.
The research is published in scientific journal PLOS ONE.