99-Million-Year-Old Snail Fossilized in Amber While Giving Birth

The mother snail and her young, marked with numbers. Image Credit: Tingting Yu

 A snail that lived alongside the dinosaurs has been found, imprisoned in amber for 99 million years, providing us with unprecedented detail of such an ancient mollusks anatomy. Even better for science – although worse for the snail – it had just given birth, and at least some of its newborns were close enough to be encased in the same lump of amber.

Simply the fact the snail gave birth to live young is a significant finding. A few land snails today have live young, and we have a record of this from 19 million years ago, but egg-laying is far more common. It's possible the same was true in the Cretaceous, but a single contradictory data point throws that into question. This is the oldest evidence of viviparity (live birth) we have found among snails.

Land snails are usually preserved as fossilized snail shells or imprints, while preservation of their soft bodies is a rarity. "Our new amber find is truly remarkable for this reason as well," explains Dr. Adrienne Jochum of the Senckenberg Research Institute and Natural History Museum Frankfurt and the Natural History Museum of the Burgergemeinde Bern, and she continues, "In a piece of Cretaceous amber from Myanmar, we discovered the body and shell of an exceptionally well-preserved female land snail shortly after the birth of her offspring, which is also preserved in the amber."

Land snails are usually preserved as fossilized snail shells or imprints, while preservation of their soft bodies is a rarity. "Our new amber find is truly remarkable for this reason as well," explains Dr. Adrienne Jochum of the Senckenberg Research Institute and Natural History Museum Frankfurt and the Natural History Museum of the Burgergemeinde Bern, and she continues, "In a piece of Cretaceous amber from Myanmar, we discovered the body and shell of an exceptionally well-preserved female land snail shortly after the birth of her offspring, which is also preserved in the amber."

Although live births are known in land snails, they are considered the exception. The researchers assume that the species, newly described as Cretatortulosa gignens, gave birth to its young alive in order to protect its offspring from predators as long as possible in the tropical forests of the Cretaceous.

Jochum explains, "Just like their modern relatives from the genus Cyclophoroidea, our new discovery probably spent its life inconspicuously on dead and rotting leaves. We assume that the young of this species—compared to egg-laying snails—were smaller and lower in number to increase their chance of survival."

According to the study, the fossil from an amber mine in northern Myanmar offers unprecedented insights into the ecology and behavior of snails that lived 99 million years ago. "Based on the discovery, we can not only make statements about the morphology and paleoecology of the animals, but we now also know that viviparous snails existed in the Cretaceous period," adds a delighted Jochum.

 
The above story is based on materials provided by Senckenberg Research Institute and Natural History Museum.