Study reveals ancient swamp in Germany was a trap for sex frogs

Ancient swamp in Germany New research shows it was a sex trap for hundreds of frogs 45 million years ago.

The researchers analyzed frog fossils found in the Geiseltal region of central Germany, which was once a swampy subtropical forest.

The Geiseltal was once home to over 50,000 ancient animals including birds, horses, bats, fish and hundreds of frogs.

Researchers say the ancient frogs were killed during mating, a phenomenon that still occurs with species that mate in water.

Female frogs can drown when a male is on them, or even die of exhaustion from the physical exertion of courtship.

According to scientists, the bodies of the ancient frogs must have sunk to the bottom of the lake, where they were broken in half by strong currents and finally petrified.

Paleontologists at University College Cork (UCC) have figured out why hundreds of fossil frogs died in an ancient swamp 45 million years ago while mating. The researchers say this frog skeleton exhibits “exceptionally high fullness and articulation.”

Daniel Falk examines the Geiseltal frogs, which died about 45 million years ago.  Fossil frogs are kept in the Collection of Natural Sciences, Halle (Saale), Germany.

Daniel Falk examines the Geiseltal frogs, which died about 45 million years ago. Fossil frogs are kept in the Collection of Natural Sciences, Halle (Saale), Germany.

The Geiseltal region in central Germany was once a swampy subtropical forest that was home to a wide variety of species.

The Geiseltal region in central Germany was once a swampy subtropical forest that was home to a wide variety of species.

GEISELTAL WAS A SUBTROPIC SWAMP

Due to its unique geological features and thousands of fossils, the former Geiseltal coalfield in Saxony-Anhalt is considered a “scientific treasure”.

This is a unique window into how the plants and animals of the Earth have evolved over millions of years.

More than 50,000 ancient animals lived here, including birds, horses, bats, fish, and hundreds of frogs.

The new study was conducted by paleontologists at University College Cork (UCC) and published in the journal Articles on paleontology.

Experts say modern frogs die during “explosive breeding” when many males congregate and compete for a small number of females over several days.

“Female frogs are at higher risk of drowning because they are often drowned by one or more males,” says senior author Professor Maria McNamara.

“This often happens with species that come together in breeding aggregations during the short, buoyant breeding season.

“What’s really interesting is that fossil frogs from elsewhere also show these features, suggesting that the mating behavior of modern frogs is indeed quite ancient, at least 45 million years old.”

Nearly 50 million years ago, during the Middle Eocene, the Earth was much warmer and the Geiseltal region was a swampy subtropical forest.

Among the inhabitants were the ancestors of the horse, large crocodiles, as well as giant snakes, lizards, land birds and many anurans (frogs and toads).

Today, the swamp is a flooded lignite mine (a giant lake called Gaizeltal Lake).

A well-preserved fossil frog skeleton from the Geiseltal Collection of the Natural Science Collections (ZNS) of the Martin Luther University Halle-Wittenberg in Halle (Saale), Germany.  hosts.  The frog probably died while mating in a swampy environment and split in two due to currents at the bottom of the lake.

A well-preserved fossil frog skeleton from the Geiseltal Collection of the Natural Science Collections (ZNS) of the Martin Luther University Halle-Wittenberg in Halle (Saale), Germany. hosts. The frog probably died while mating in a swampy environment and split in two due to currents at the bottom of the lake.

Previous studies have shown that Geiseltal frogs died after lakes dried up or oxygen in the water was depleted.

But a new analysis of the fossils has shown that the frogs were healthy when they died.

“There are no signs of predators or scavengers on the bones — there is also no evidence that they were washed away by water during a flood or that they died because the swamp dried up.” study author Daniel Falk said.

Falk added that most fossil Geiseltal frogs spend their lives on land, returning to the water only to breed, so the only explanation is that they died while mating.

The bodies of ancient frogs, after drowning, sank to the bottom of the lake, where they were broken into two parts by a strong current and petrified.

The bodies of ancient frogs, after drowning, sank to the bottom of the lake, where they were broken into two parts by a strong current and petrified.

In their study, the team questioned many theories about how the frogs died from previous studies, including algae flower poisoning, freezing, and starvation.

However, death from old age cannot be ruled out as the cause of death for at least some specimens, the researchers add.

“Instances are presented in a wide range of sizes and, presumably, ages,” their article says.

“Taken together, these data suggest that many Geiseltal anurans represent mating-related deaths, at least some of which may have occurred as mass mortality.”

MALE FROG SQUEEZING A DEAD FEMALE TO EXTRACT HER EGGS

In the Amazon, male frogs squeeze a dead female to extract her eggs, a 2013 study published in the Journal of Natural History found.

Brazilian researchers observed male Rhinella proboscidea using what they call a “functional necrophilia strategy.”

They extract oocytes from the abdomen of unfortunate females who died in the mating struggle, and then fertilize them.

From an evolutionary point of view, the use of eggs from dead females minimizes the losses that both partners can suffer as a result of the so-called “explosive breeding”.

Explosive breeding is when many males gather and compete for a small number of females over several days.

The male can reproduce successfully despite not having access to a live female or spending too much energy in battle to get her; the female’s eggs are fertilized even though she herself is dead.

During explosive breeding, males may tire of competing and finding a scarce mate, or of trying to force other males away from receptive females.

The females themselves may be inadvertently crushed, drowned, or simply exhausted under the weight of their many suitors.