A snail preserved in amber with an intact fringe of tiny, delicate hairs along its shell is helping biologists better understand why one of the world’s slimiest animals could develop such a groovy hairstyle.
This unusual mollusk fossil, found in Myanmar’s Hukawng Valley, has rows of stiff, tiny hairs, each between 150 and 200 micrometers long, following the swirl of its 9 millimeter long and 3.1 millimeter wide shell. high.
IIt’s also not the first hairy snail discovered to join a closed club of capped gastropods.
“This is already the sixth species of hairy-shelled Cyclophoridae – a group of tropical land snails – discovered to date, embedded in Mesozoic amber, approximately 99 million years old,” says the paleontologist. from the University of Bern Adrienne Jochum.
It’s not just bizarre extinct creatures, either. Several land snails still living today also have fuzzy shells.
A team of researchers led by malacologist Jean-Michel Bichain from the Museum of Natural History and Ethnography of France named the newly discovered animal Archaeocyclotus brevivillosus – its species name combining the Latin words small (brevis) and hirsute (villōsus).
Of 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 helped snails transition from an aquatic environment to life on land during the Mesozoic period 252 to 66 million years ago, the researchers suggest.
The hairs are formed from the protein-filled outermost layer of the snail’s shell – the shell skin – called the periostracum. Adding hair to a shell would cost tiny animals energy, so it must have given these tiny prehistoric snails some sort of selective advantage in their tropical environment to make it worthwhile.
Bichain and his team believe these could have included water retention and protection against desiccation of the shell, allowing these animals to branch out into drier ground niches. And just like our own mammalian hair, it’s possible that the down from the shell helped with thermoregulation.
“The hairs could also have served as camouflage or to protect the snail from direct attack by stalker birds or ground predators,” says Jochum. “They may also have played a role in the thermal regulation of the snail by allowing tiny droplets of water to adhere to the shell, thus serving as an ‘air conditioner’. And finally, it cannot be ruled out that the hairs provided a sexual selection advantage.”
In addition to shaggy snails, Myanmar amber has preserved more than two thousand unique species, from delicate flowers to a delightfully preserved feathered dinosaur tail, providing an unobstructed window into the biodiversity of the Cretaceous period.
Signs of ancient species from the tropics are hard to find, since the warm, humid conditions are ideal for the decay and recycling of organic matter. Thus, animals preserved in amber fill in some of these gaps in our fossil record, providing details of soft tissues and even metallic colors of ancient insects that would otherwise be lost over time.
One such specimen preserved what may be the earliest evidence of live births in land (rather than egg-laying) snails, with newborn snails still attached to their mothers by mucus.
Unfortunately, while amber contains many exquisite and valuable specimens, the fossil trade currently funds devastating conflicts in Myanmar. In recognition of this terrible problem, the researchers note that the amber-wrapped snail specimen was collected legally in 2017, before the current conflicts resumed.
Their study was published in Cretaceous research.
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