2023-04-14 12:45:00
There are more than 1,460 living species of bats in the world. These flying mammals are found in almost all parts of the world, with the exception of the polar regions and some remote islands. The origin of bats is shrouded in mystery. Bats have a notoriously incomplete fossil record, with some studies estimating that up to 88% of their fossil record is currently missing.
In the Green River Formation of Wyoming, USA, a remarkable early Eocene fossil bed, more than 30 bat fossils have been discovered in the past 60 years, but until now they were all thought to belong to one or the other of two species.
Reviewing again skeletons from that site, a team made up of, among others, Tim B. Rietbergen, of the Naturalis Biodiversity Center in Leiden, the Netherlands, and Nancy Simmons, of the American Museum of Natural History in the US city of New York, has discovered and described a third species, which was hitherto unknown.
This species has been given the name Icaronycteris gunnelli, and its scientific description has been made from fossil skeletons kept at the American Museum of Natural History in New York and at the Royal Ontario Museum in Canada. These fossil skeletons were found at a greater depth than the other bat skeletons from this site. Although there are doubts about the exact age of each of the layers in the site, their position in the rocks suggests that these skeletons are the oldest found so far. For this reason, it is believed that they are probably the oldest bat fossil skeletons among all those that are preserved whole or almost whole.
The extinct bat lived in what is now Wyoming, according to some estimates, about 52 million years ago.
A fossil skeleton of Icaronycteris gunnelli, kept at the American Museum of Natural History in New York. (Photo: Mick Ellison / © AMNH)
Using skeletal CT scans, the researchers compared the new species to other bats from the Eocene period, which lasted from about 56 million years ago to about 34 million years ago. The newly discovered species is the smallest in body size of all bats found in the Green River Formation of Wyoming, and had comparatively short forearms and hindlimbs.
The results of the Icaronycteris gunnelli analysis support the suspicion that bats diversified rapidly across multiple continents during the Eocene.
Although the Icaronycteris gunnelli skeletons are the oldest bat fossils from this site, they are not the most primitive, supporting the hypothesis that the evolution of bats from the Green River Formation of Wyoming occurred separately from that of the rest of the bats. bats of the world during the Eocene.
The study is titled “The oldest known bat skeletons and their implications for Eocene chiropteran diversification”. And it has been published in the academic journal PLoS ONE. (Fountain: NCYT de Amazings)
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