The Late Miocene Bats (Chiroptera, Mammalia) from the Pannonian region, Slovakia
by: Florentin Cailleux, Lars van den Hoek Ostende and Peter Joinak
Summarized by: Brieahna Wilson, a current biological sciences major at Binghamton University. She is currently a senior and plans to continue her education by getting a master’s in teaching which she will use to teach science to K – 12. When she is not busy with classes or work, she enjoys baking, painting and going to concerts when possible.
Hypothesis/purpose of paper: Bat (scientific name: Chiroptera) fossils are relatively rare compared to the amount of fossilized rock that we have. Bats tend to live in hot and high humidity areas, which lead to faster decomposition. Additionally, they have very small and fragile bones which oftentimes may get destroyed or scavenged before fossilization can occur. Karstic sites are areas such as caves that are typically created by dissolved limestone. They have been very important in paleontology for the discovery of fossils, however, this study found that fluviolacustrine deposits (rock formations formed at the bottom of lakes and stream waters created by sediments running from rivers into lakes) also held a wide array of fossils that were useful in determining the diversity of the bat population from the late Miocene, roughly five to ten million years ago. Scientists describe the diversity of bats in this article.
Data: Scientists use newly discovered fossils of numerous upper Miocene fluviolacustrine (created from rivers running into lakes) deposits from Slovakia from three locations (called Borský Svätý Jur, Studienka A, and Krásno). All of the small mammals found (in this case, bats) were not new species. These fossils were studied and their preserved features, particularly their teeth, were measured.
Methods: The dental fossils of the bats were measured and compared to one another in order to determine how many species of bats were present in these areas. A digital measuring microscope was used to measure different dental features such as canines, incisors, molars, mandibles (jaws) using their height, length and width. See Figure 1 below.
Results: Seven different taxa, or groups, were identified by comparing the differences in the teeth and jaws of the bat fossils. Differences in the sizes of teeth and the complexities of their shapes helped to identify and compare the fossils. The first small Miocene bat had high dental complexity, so there were many grooves and cusps along the teeth which helped to identify them as a species that was already established. The second group lacked larger upper canines.For other groups, the size and shape of molars were used to identify the species. There were also specimens with larger grooves or smoother areas on the teeth than other fossils. While many of the fossils were incomplete, the available details There helped scientists decide what group they belonged to.
Significance: High diversity in areas such as this one are typically found in karst (cave) environments, not fluviolacustrine. This is because karstic sites have more stable conditions and offer more protection for the preservation of fossils compared to fluviolacustrine which can be found in areas with more movement that could disrupt fossilization, especially in more delicate fossils, like bats. Discovering this level of diversity in a different material than usual showcases the importance of studying a broader scope of geologic areas. This could lead to more breakthroughs with more fossils in the future, allowing a clearer understanding of what animals existed and how they may have changed over time.
Broader Impact: The fossil record of bats is not very extensive because their bones are fragile and have a lower chance of getting fossilized. Because of this lack of fossilization, there has not been a very thorough understanding of bat diversity. This study helps to improve the understanding of bat diversity in this area from ten million years ago which can increase diversity estimates. This could also mean more information for understanding how other organisms existed during this time period and how bats may have interacted with them.
Citation: Cailleux, F., van den Hoek Ostende, L., & Joniak, P. (2025). The late Miocene Bats (Chiroptera, Mammalia) from the Pannonian region, Slovakia. Journal of Paleontology, 99(4), 975–991. doi:10.1017/jpa.2025.10136