Researchers unearthed a pair of 52-million-year-old bat skeletons in southwestern Wyoming. They are now considered the oldest bats ever found and have led to changes in the supposed family tree of bats.
Two of the Oldest Bats Ever Found
Live Science reports that, compared to the Icaronycteris index, which is its closest bat relative, these two recently found bats were quite smaller. In fact, if its wings were folded against its frame, the bat could fit in a human hand.
The remains came from an area that paleontologists have dubbed Fossil Lake in Wyoming, as reported by the Smithsonian Magazine. The layers of rock are known to contain preserved birds, mammals, fish, and other creatures from around 52 million years ago.
Now, these new bat species, labeled Icaronycteris gunnelli, have been added to the bat family tree. As researchers compare this new bat species with its flying relatives, they are bound to get a deeper understanding of the creatures during ancient times. Findings regarding the recent bat discovery were published in the PLOS One journal.
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Restructuring the Bat Family Tree
Tim Rietbergen, the study's lead author and a bat paleontologist and collection manager from the Naturalis Biodiversity Center, told Live Science that, upon seeing the first remains, he instantly thought that they were different. Rietbergen adds that, since they were spotted in lower layers of sediment compared to other bat fossils, these recently found ones now represent the earliest known bat skeletons.
Interestingly, Rietbergen did not find these skeletons on the Fossil Lake site. He found it online, being sold by a commercial dealer, as reported by the Smithsonian Magazine. Nevertheless, the green limestone and the bones that had a shade of tan gave away the bats' Fossil Lake origins.
To learn more about the creature's evolutionary history, these new fossils were compared with the skeletons of six Eocene bat species. They were also compared with isolated teeth of two extinct bat species and the skeletons of bats that are alive today.
Findings revealed that the newly found bat skeletons were part of a never-before-seen Icaronycteris species. It was then named I. gunnelli, mirroring the late Greg Gunnell, a bat biologist.
Rietbergen explains that, after comparing its dimensions, they found that the remains were clearly from a different species. This made Rietbergen wonder if bat diversity during the early Eocene, where the evolution of bats dates back to, was higher than previously assumed.
The weight of the I. gunnelli did not exceed an ounce. This means that its body mass is the same as the I. index, despite the latter probably being quite bigger. The study notes that the discrepancy between the creature's wingspan and reconstructed weight could be attributed to bone deformation caused by fossilization.
Emma Teeling, a zoology professor from the University College Dublin who did not join the study, says that this recently described species is now one of the earliest known bat skeletons that are articulated. While they shed light on the earliest bat fossils' phylogeny, Professor Teeling adds that there are still phylogenetic queries that could only be answered by finding other complete and more defined bat bones.
Rietbergen notes that there are still a lot of things that remain a mystery. As they get a better view of bat diversity, they will be able to look into evolutionary adaptations and potentially find clues that could lead them closer to bat ancestry.
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