Ancient Remains Unearthed in Wyoming Unveil Oldest Bat Species Yet, Dating Back 52 Million Years.
The fossil records of Wyοmiпg reveal the existence of the oldest bat species, previously unknown, dating back 52 million years.
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Scientists have described a new species of bat based on the oldest bat skeletons ever recovered. The study on the extinct bat, which lived in Wyoming around 52 million years ago, supports the idea that bats diversified rapidly across multiple continents during this time.
There are more than 1,460 living species of bats found in almost all parts of the world, with the exception of the polar regions and some remote islands. In Wyoming’s Green River Formation, a remarkable deposit of early Eocene fossils, scientists have discovered more than 30 bat fossils in the past 60 years, but until now they were all thought to represent the same two species.
A photo of one of two newly described bat skeletons representing Icaronycteris gunnelli. This specimen, the holotype, is now in the research collections of the American Museum of Natural History. Credit: Mick Ellison/AMNH
“Eocene bats have been known from the Green River Formation since the 1960s. But interestingly, most of the specimens that have emerged from that formation were identified as representatives of a single species, Icaronycteris index, until about 20 years ago, when a second species of bat belonging to another genus was discovered,” said study co-author Nancy Simmons. , curator-in-charge of the Museum’s Department of Mammalogy, who helped describe that second species in 2008. “I always suspected there must be even more species there.”
In recent years, scientists at the Naturalis Biodiversity Center began to take a close look at the Icaronycteris index by collecting measurements and other data from museum specimens.
“Paleontologists have collected so many bats that they have been identified as index Icaronycteris, and we wondered if there were actually multiple species among these specimens,” said Tim Rietbergen, evolutionary biologist at Naturalis. “Then we learned of a new skeleton that diverted our attention.”
The exceptionally well-preserved skeleton was picked up by a private collector in 2017 and purchased by the Museum. When the researchers compared the fossil to Rietbergen’s extensive dataset, it clearly stood out as a new species. A second fossil skeleton discovered in the same quarry in 1994 and in the collections of the Royal Ontario Museum was also identified as this new species. The researchers gave these fossils the species name Icaronycteris gunnelli after Gregg Gunnell, a Duke University paleontologist who died in 2017 and made extensive contributions to the understanding of fossil bats and evolution.
Although there are fossil bat teeth from Asia that are slightly older, the two I. gunnelli fossils represent the oldest bat skeletons ever found.
“The Fossil Lake deposits of the Green River Formation are simply amazing because the conditions that created the paper-thin limestone layers also preserved almost everything that settled on the bottom of the lake,” said Arvid Aase, administrator of the park and conservator of Fossil Butte National Monument. , in Wyoming. “One of these bat specimens was found lower in the section than all other bats, making this species older than any of the other bat species recovered from this deposit.”
While the I. gunnelli skeletons are the oldest bat fossils from this site, they are not the most primitive, supporting the idea that Green River bats evolved separately from other Eocene bats worldwide.
“This is a step forward in understanding what happened in terms of evolution and diversity in the early days of bats,” Simmons said.
