Ancient snail from 99 million years ago discovered with hairs that grow on the shell: ScienceAlert

Ancient snail from 99 million years ago discovered with hairs that grow on the shell: ScienceAlert

An amber-preserved snail with an intact fringe of tiny fine bristles along its shell is helping biologists better understand why one of the world’s slimiest animals could develop such an invading haircut.

This unusual mollusk fossil, found in Myanmar’s Hukawng Valley, has lines of stiff, tiny hairs, each between 150 and 200 micrometers long, that trace the vortex of its 9-millimeter-long, 3.1-millimeter-high shell.

lIt’s also not the first hairy snail discovered to join an exclusive club of hooded gastropods.

“This is already the sixth kind of furry shells Cyclophoridae – a group of tropical land snails – found so far, embedded in Mesozoic amber, about 99 million years old,” explains University of Bern paleontologist Adrienne Jochum.

They are not just some weird extinct critters. Several land snails still alive today also have fluffy shells.

Close up of a dark brown snail shell covered in silvery hairs.
A modern hairy snail, Hispis hair. (scubaluna/iStock/Getty Images Plus)

A team of researchers led by malacologist Jean-Michel Bichain of the Museum of Natural History and Ethnography in France named the newly discovered animal Archaeocyclotus brevivillosus – the species name that combines the Latin words small (brevis) and shaggy (villōsus).

Of the eight species found in Myanmar amber, six have hairy shells, suggesting that this may be the ancestral state of these land snails. In fact, this down may have aided the transition from an aquatic environment to life on land during the Mesozoic 252 to 66 million years ago, the researchers suggest.

The hairs are formed from the outer protein-filled layer of the cochlea – the skin of the snail – called the periostracum. Adding hairs to a shell would cost the little animals energy, so it must have given these tiny prehistoric snails some sort of selective advantage in their tropical environment to make it worthwhile.

Close up of snail shell edge with hairs
The edge of the cochlea is lined with small hairs. (Senckenberg)

Bichain and team speculate that this could be water retention and protection from shell drying out that allowed these animals to branch out into drier bottom niches. And like our own mammalian hair, it’s possible that the shell fuzz helped with thermoregulation.

“The bristles may also have served as camouflage or protected the snail from direct attack by prowling birds or bottom predators,” explains jochem. “They may also have played a role in the thermal regulation of the snail by allowing small water droplets to adhere to the shell, thereby serving as an ‘air conditioner’. Finally, it cannot be ruled out that the hairs offered an advantage in sexual selection. “

Close-up of the snail shell in amber with details.
Archaeocyclotus brevivillosus. (Senckenberg)

In addition to shaggy slag, Myanmar amber has preserved more than two thousand unique species from delicate flowers to a beautifully preserved feathered dinosaur tailwhich offer a wonderful window into the Cretaceous biodiversity.

Signs of ancient species from the tropics are hard to find, as the warm, humid conditions are ideal for the disintegration and recycling of organic matter. So animals preserved in amber fill some of these gaps in our fossil record and provide details on: soft tissues and even the metallic colors of old insectsthat would otherwise be lost in time.

One such copy preserved what may be the first evidence of live births in land snails (instead of laying eggs), with newborn snails still attached to their mother by means of mucus.

Unfortunately, although the amber contains many precious exquisite specimensfossil trade is currently funded devastating conflicts in Myanmar. In recognition of this terrible problem, the researchers note that the amber-encased snail specimen was legally collected in 2017, before current conflicts resumed.

Their study was published in Chalk research.

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