The world of paleontology never ceases to captivate us with its discoveries of ancient creatures that once roamed the Earth. Recently, researchers have unearthed a remarkable discovery – a collection of bat skeletons that date back to 52 million years ago. Bats have always been intriguing creatures that have captured the imaginations of people for centuries. With their unique echolocation abilities, they effortlessly navigate through the night skies in search of prey. The fossilized bat skeletons have given us invaluable insights into the evolution of these fascinating creatures and have even led to the discovery of a new species, making it a significant breakthrough in our understanding of their evolutionary history.
These bat fossils represent the oldest specimens ever found and are believed to have lived in Wyoming over 52 million years ago. This extinct paleontological find supports the notion that bats diversified rapidly on multiple continents during this period. Today, there are more than 1,460 living species of bats found across the globe, except for the polar regions and a few remote islands. In the Green River Formation of Wyoming, which boasts of an extraordinary fossil deposit from the early Eocene period, over 30 bat fossils have been discovered in the last 60 years. Previously, it was believed that these fossils represented only two species, but the latest discovery has proven otherwise.
The Green River Formation has been a rich source of Eocene bats since the 1960s. However, it’s intriguing to note that most of the specimens found there were initially believed to be from a single species, Icaronycteris index. This notion changed only about 20 years ago, with the discovery of a second bat species belonging to another genus. Nancy Simmons, a co-author of the study and curator-in-charge of the Museum’s Department of Mammalogy, who helped describe that second species in 2008, always suspected that there could be even more species lurking in the formation.
In recent years, scientists from the Naturalis Biodiversity Center have taken a closer look at the Icaronycteris index by collecting measurements and data from museum specimens. Their research led them to wonder whether there were multiple species among these specimens, considering that paleontologists had amassed a considerable number of bats identified as Icaronycteris index. This curiosity eventually led them to a new skeleton that captured their attention.
In 2017, a private collector unearthed an incredibly well-preserved skeleton that caught the attention of researchers at the Museum. After comparing the fossil to Tim Rietbergen’s extensive dataset, it was evident that they had stumbled upon a new species. Another fossil skeleton discovered at the same quarry in 1994 and held in the collections of the Royal Ontario Museum was also identified as belonging to this new species. In honor of the late Duke University paleontologist Gregg Gunnell, who made significant contributions to the understanding of fossil bats and evolution, the researchers named these fossils “Icaronycteris gunnelli.”
The newly discovered species, according to the researchers, was tiny, weighing just around 25 grams, equivalent to five marbles. Despite its small size, it had already developed the ability to fly and was likely capable of echolocation. The bat probably lived in the trees surrounding the lake and hunted insects by flying over the water.
Matthew Jones, a paleontology researcher at Arizona State University and one of the study’s authors, suggests that bats are descendants of tiny, insect-eating mammals that lived in trees. Identifying the precise small mammal species related to bats is challenging, as numerous distinct types exist, and most of these mammal species are familiar only through limited findings of their teeth and jaws.
The unique limestone layers of Fossil Lake deposits in the Green River Formation have preserved an array of ancient creatures and plants that have fascinated paleontologists. The recently discovered bat fossils from Wyoming belonged to the early Eocene epoch, a time of rapid diversification of life on Earth due to warming temperatures.
Although the bat fossils share many similarities with modern-day bats, they also possess distinct features that shed light on their evolutionary history. Researchers noted that the hind limbs of the newly discovered species were thicker and more robust than those of modern bats, which have thin and lightweight bones for flight. This suggests that these ancient bats had a stronger grip, possibly to climb trees.
Another interesting feature of these fossils is the presence of a claw on the index finger in addition to the thumb claw found in most bats today. This adaptation may have helped the bats climb or grip onto surfaces, indicating that they were in a transitional phase from climbers to expert fliers.
The findings from these fossilized bat skeletons are significant because they provide insights into the evolutionary history of these fascinating creatures, which have mastered the skies for millions of years. The discovery also highlights the importance of paleontological research and the unique fossil deposits that provide valuable windows into the distant past.
