Paleontologists have described a new species of cyclophorid snail found in a piece of mid-Cretaceous amber excavated from a mine in Myanmar (formerly known as Burma).
Archaeocyclotus brevivillosus. Image credit: Senckenberg Research Institute and Natural History Museum.
The newly-discovered snail species lived during the Cretaceous period, between 99 and 98 million years ago.
Named Archaeocyclotus brevivillosus, the ancient creature belonged to the snail family Cyclophoridae.
Its shell is characterized by densely implanted hairs between 150-200 micrometers in length that emerge at growth line margins from the shell periphery.
“The fossil snail is 2.65 cm long, 2.1 cm wide, and 0.9 cm tall,” said Dr. Adrienne Jochum, a paleontologist at the Senckenberg Research Institute and Natural History Museum and Bern’s Natural History Museum.
“The outer margin of its shell is lined with short hairs that are bunched around the shell opening.”
Archaeocyclotus brevivillosus is the eighth cyclophorid snail species described from Burmese amber, six of which also have hairy shells.
“It is not uncommon for the shells of fossil and present-day land snails to be embellished with ridges, hairs, nodules, or folds,” Dr. Jochum said.
“However, the development of such ‘decoration’ is still a complex process that usually does not occur without a purpose.”
Dr. Jochum and her colleagues think that the hairiness offered the cyclophorid snails an evolutionary advantage.
“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,” Dr. Jochum said.
“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.”
“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.”
A paper on the findings appears in the journal Cretaceous Research.
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Jean-Michel Bichain et al. 2022. Archaeocyclotus brevivillosus sp. nov., a new cyclophorid land snail (Gastropoda: Cyclophoroidea) from mid-Cretaceous Burmese amber. Cretaceous Research 140: 105359; doi: 10.1016/j.cretres.2022.105359
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