Smithsonian Magazine has a story about a fossil bat from Wyoming.  Bats are underrepresented in the fossil record due their small size and even smaller bones.  Unfortunately, they also live in areas that don’t usually form fossils.  The Green River Formation in Wyoming, which dates to the Eocene about 52 million years ago, has yield a few examples of fossil bats.   This specimen, which was spotted for sale online, represents a new species – Icaronycteris gunnelli.  It was described in a paper in the journal PLOS One.

The fossil record is biased against bats. The flying mammals are small, making their fossilized remains very hard to find. And their light skeletons—ideal for flying around—mean it takes special circumstances for their bodies to be preserved. And yet, against these odds, paleontologists recently uncovered the exceptionally complete skeleton of what now stands as the earliest known bat.

To date, the most complete early bat fossils have come from an area paleontologists call Fossil Lake in Wyoming. The rock layers are world-famous for containing beautifully preserved fish, birds, mammals and other organisms that lived in the area about 52 million years ago. Among the stunning fossils recovered from these rocks, Naturalis Biodiversity Center paleontologist Tim Rietbergen and colleagues report Wednesday in PLOS One, are fossils of a new bat species the researchers have named Icaronycteris gunnelli. By comparing this new species with other early bats, paleontologists are beginning to develop a deeper understanding of how bats spread around the world in that period.

The Field Museum of Natural History has a specimen of Icaronycteris in its Evolving Planet exhibit.  It was also found in the Green River Formation.

The oldest known complete bat skeletons come from the sediments of the Green River Formation and are critical in deciphering the early evolution of bats and their ability to fly. From these amazingly complete fossils like the Icaronycteris index species pictured here, we can also see early features, such as well-developed claws on the index fingers, which are no long present in modern species.

© The Field Museum, GEO86416_106d, D. Scher