(CNN) Two 52-million-year-old bat skeletons discovered at an ancient lake bed in Wyoming are the oldest bat fossils ever found — and they reveal a new species.
Tim Rietbergen, an evolutionary biologist at the Naturalis Center for Biodiversity in Leiden, the Netherlands, identified a previously unknown bat species when he began collecting measurements and other data from museum specimens.
“This new research is a step forward in understanding what happened in terms of evolution and diversification in the early days of bats,” he said.
Today, there are more than 1,400 living species of bats worldwide, except for the polar regions. But how the creatures evolved to become the only mammals capable of powered flight is not well understood.
Shown here are CT visualizations of Icaronycteris gunnelli, including the following views: a) a ventral view of the skull; b) labial view of the right wall; c) the skeleton of the dorsal view; d) Occlusal view of the right upper jaw.
The bat fossil record is patchy, and the two fossils that Ritbergen identified as a new species were lucky finds—exceptionally well preserved and revealing the entire skeletons of the animals, including the teeth.
“The skeletons of bats are small, light and fragile, which is unfavorable to the fossilization process. They simply do not preserve well,” he said.
The newly discovered extinct species of bat — Icaronycteris gunnelli — wasn’t much different from the bats that fly today. Its teeth revealed that it subsisted on a diet of insects. It was small, weighing only 25 grams (0.88 ounces).
“If it folded its wings next to its body, it would be easy to get it in your hand. Its wings were relatively short and wide, reflecting a more flapping style of flight,” said Rittbergen.
This particular bat lived when the Earth’s climate was warm and humid. The two skeletons studied by Rietbergen survived eons likely because the creatures fell into a lake, leaving them out of reach of predators and in an environment more suitable for fossilization. The ancient lake bed is part of the Green River Formation in Wyoming and has yielded a number of bat fossils.
One of the two fossils was collected by a private collector in 2017 and purchased by the American Museum of Natural History. The other belongs to the Royal Ontario Museum in Toronto and was found in 1994.
Research published in The scientific journal PLOS One Wednesday.