An ancient swamp was a sex death trap for randy frogs, Irish researchers have discovered.
The marsh - which existed 45 million years ago - claimed the lives of frogs while they were mating.
It has been described as a “watery death trap” which killed over 50,000 ancient beasts.
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Frogs were the most commonly killed as they would have drowned in the murky water while mating - a phenomenon which still occurs today.
Female frogs are known to drown with a male hitched on their back - but can even die from exhaustion caused from the physical effort of swamp bonking.
Sometimes female frogs are submerged by more than one male.
The bodies of the ancient frogs sank to the bottom of the lake and were split in half by strong currents before being fossilised.
Researchers at University College Cork analysed the long-legged fossils found in the Geiseltal area in central Germany.
The hotter climate of the Earth 50 million years ago made the area a swampy subtropical forest.
Fossils of birds, horses, bats and fish were also recovered.
Previous studies have suggested that the ancient frogs died during the desiccation of lakes or through oxygen depletion in the water.
The actual cause of death has been a mystery until now.
The boffins called the once-swamp a “scientific treasure trove” that provides a unique window into how plants and animals have evolved over millions of years.
Study lead Daniel Falk said: “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.
“By process of elimination, the only explanation that makes sense is that they died during mating.”
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