Researchers have unearthed the oldest set of bat bones yet discovered in western Wyoming, which belong to a new species named Icaronycteris gunnelli. The fossils are incredibly complete, showing all the animals’ bones in lifelike positions, and are estimated to be around 52.5 million years old. The find, reported in the journal PLOS ONE, sheds light on the early evolution of bats and adds to our understanding of the diversity of bats that existed during the early Eocene epoch.
The Icaronycteris genus is not new to science, and another species from the same genus has been previously discovered in the same limestone rocks known as the Green River Formation. However, the newfound skeletons are the oldest and most complete examples of this genus ever found. The researchers note that other bat fossils found in the same formation are preserved at least 40 centimeters above the new fossils and are thus younger, but it’s difficult to determine their exact age because the rate of sediment accumulation is unknown.
The analysis of the fossils indicates that Icaronycteris gunnelli is the smallest known member of the genus, with a wingspan almost 7 percent smaller than that of its closest known cousin. The team estimates that during its lifetime, Icaronycteris gunnelli weighed somewhere between 22.5 and 28.9 grams, roughly half the weight of a tennis ball.
The arrangement of bones in Icaronycteris gunnelli’s feet suggests that, like many modern bats, it hung upside down when roosting. The researchers note that the skeletons are so similar to those of some modern bats that it’s difficult to determine what type of creature bats evolved from.
Despite the discovery of these fossils, the origin of bats remains a mystery. The oldest known bats lived about 56 million years ago, but the fossils of those species are mostly isolated teeth, not entire skeletons. The discovery of the Icaronycteris gunnelli skeletons provides valuable insights into the early evolution of bats and expands our knowledge of the diversity of bats during the early Eocene epoch.
The Green River Formation has been a prolific source of vertebrate fossils since its discovery in the 19th century. The limestone rocks formed as lake sediments and have preserved a remarkable record of life during the Eocene epoch. The fossils found in the formation include fish, turtles, crocodiles, birds, and mammals, providing a rich source of information for researchers interested in understanding the evolution of life on Earth.
The discovery of the Icaronycteris gunnelli skeletons adds to this record, providing new insights into the evolution of bats. The skeletons will be studied further to understand their biology and behavior, and to shed light on the early evolution of one of the most fascinating groups of mammals on Earth.
In conclusion, the discovery of the oldest and most complete bat fossils to date in western Wyoming is an exciting development for paleontologists and bat enthusiasts alike. The fossils of Icaronycteris gunnelli provide valuable insights into the early evolution of bats and expand our knowledge of the diversity of bats during the early Eocene epoch. The discovery highlights the importance of the Green River Formation as a source of information about the evolution of life on Earth and underscores the importance of continued research in this area.
