A swamp in the Geiseltal area in central Germany was a ‘sex death trap’ 45 million years ago, according to a new study. After analyzing frog fossils from the swap, paleontologists from University College Cork in Ireland determined how these frogs perished.
This area is considered a 'scientific treasure trove,' containing fossils of over 50,000 different ancient species, including birds, fish, bats, horses and frogs. Due to its geological features, the Geiseltal area — once a coalfield — contains thousands of fossils and can give researchers a better idea of what life looked like millions of years ago.
During the mid-Eocene period, nearly 50 million years ago, the Earth’s climate was warmer, making the Geiseltal area more swampy and subtropical. It was an ideal home for ancient lizards, crocodiles, snakes, frogs and toads. Previous findings suggested that the frogs found at the bottom of the swamp died as the water dried up or due to oxygen depletion in the water. However, these new findings suggest their deaths had more to do with sex.
“As far as we can tell, the fossil frogs were healthy when they died, and the bones don’t show any signs of predators or scavengers — there’s also no evidence that they were washed in during floods, or died because the swamp dried up,” says Daniel Falk, lead author of the study in a press release. “By process of elimination, the only explanation that makes sense is that they died during mating.”
Researchers determined that the species of frog they found fossilized, spent their lives on land and would return to the water to mate. What likely happened is that as the female frog entered the water, males competed to mate with her and overcame her until she drowned. This is something still seen today.
“Female frogs are at higher risk of drowning as they are often submerged by one or more males — this often happens in species that engage in mating congregations during the short explosive breeding season,” says senior author Maria McNamara in a press release. “What’s really interesting is that fossil frogs from other sites also show these features, suggesting that the mating behaviors of modern frogs are really quite ancient and have been in place for at least 45 million years”.