Researchers found a hairy snail in a 99-million-year-old amber

Mesozoic land snails most likely benefited from their fine hairs.
Nergis Firtina
A 99-million-year-old amber.
A 99-million-year-old amber.

Senckenberg Natural History Museum 

A piece of amber that is thought to be 99 million years old has been discovered new species of land snail by international researchers.

As stated by Senckenberg Natural History Museum, the discovery suggests that this hairy snail offers an evolutionary advantage to Mesozoic land snails.

The team, led by first author Dr. Jean-Michel Bichain of the Museum of Natural History and Ethnography in Colmar, France, concluded that having hairs may have given the mollusks a selective advantage during their evolution in their study, which was published in the academic journal Cretaceous Research.

Using conventional microscopy and 3D X-ray micro-computed tomography, the tiny hairs, measuring about 150 to 200 micrometers in length, were found on the shell of the recently discovered species Archaeocyclotus brevivillosus sp. nov.

Researchers found a hairy snail in a 99-million-year-old amber
The fossil snail is 26.5 millimeters long, 21 millimeters wide, and 9 millimeters tall.

"This is already the sixth species of hairy-shelled Cyclophoridae, a group of tropical land snails found so far, embedded in Mesozoic amber, about 99 million years old," explains Dr. Adrienne Jochum from the Senckenberg Research Institute and Natural History Museum in Frankfurt and the Natural History Museum in Bern.

"It is not uncommon for the shells of fossil and present-day land snails to be embellished with ridges, hairs, nodules, or folds; however, the development of such 'decoration' is still a complex process that usually does not occur without a purpose," she also explained.

Originally from Burma

Eight different Cyclophoridae species have been found in Burmese amber, and six of them had bristly shells. This is not a coincidence, according to the scientists. They believe the snails' hairiness gave them an evolutionary advantage.

"The new species, Archaeocyclotus brevivillosus, originates from a Cretaceous amber mine in the Hukawng Valley in Burma, where it was collected prior to 2017. The fossil snail is 26.5 millimeters long, 21 millimeters wide, and 9 millimeters tall. The shell's outer margin is lined with short hairs that are bunched around the shell opening. Its name derives from the Latin words brevis (short or small) and villōsus (hairy or shaggy)," added Dr. Jochum.

"For example, the hairs could improve the animals' ability to better cling to plant stalks or leaves—something that has already been observed in present-day snails. They may also have played a role in thermal regulation for the snail by allowing tiny water droplets to adhere to the shell, thereby serving as an 'air conditioner.' Or they may have protected the snail shell from being corroded by the highly acidic soil and leaf litter of the ancient tropical forest floor," says Jochum, summarizing the possible benefits of hairs for the snails.

"The bristles could also have served as camouflage or protected the snail against a direct attack by stalking birds or soil predators. And finally, it cannot be ruled out that the hairs provided an advantage in sexual selection."

Abstract

Land snails in mid-Cretaceous Burmese amber (ca. 99–98 Ma) have attracted great interest from paleontologists in recent years. Here we describe a new species of the genus Archaeocyclotus belonging to the family Cyclophoridae, from a well-preserved fossil, using classic light microscopy and modern micro-CT scans with computer 3D reconstructions. The shell of Archaeocyclotus brevivillosus sp. nov. is characterized by short, densely implanted periostracal hairs that emerge at growth line margins from the shell periphery. This new species is the eighth cyclophorid species described from Burmese amber, six of which also have hairy shells. It thus, reinforces the hypothesis that the hairiness is an ancestral state in cyclophorids and that it may have played a role through multiple selective advantages in the terrestrialization of the group during the Mesozoic.

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