NEED TO KNOW
Scientists discovered microscopic embryos and larvae preserved inside a 125-million-year-old shellfish fossil
Researchers say it is the oldest known evidence of maternal care in shellfish
The fossil was found on England’s Isle of Wight, a site known for its dinosaur-era remains
A fossilized shellfish discovered in England has given scientists an extraordinary glimpse into family life during the age of dinosaurs.
Researchers say a 125-million-year-old freshwater shellfish fossil contains microscopic embryos and larvae preserved inside its body, making it the oldest known evidence of maternal care in shellfish. The findings were published in the journal Scientific Reports and announced by researchers from the Geological and Mining Institute of Spain (CSIC), who led the international study.
What makes the discovery so unusual is that scientists didn’t just find the shell.
They also found fossilized soft tissues inside the animal, including reproductive structures, gill tissues, and developing young. Soft tissue rarely survives the fossilization process because it typically decays soon after an animal dies.
“This is the earliest known fossil evidence that these shellfish cared for and protected their developing young,” Dr. Martin C. Munt, a fossil mollusk specialist and visiting academic at the University of Portsmouth, said in a statement.
“Until now, this reproductive strategy was known only from living species,” he added.
Thin section of one of the pregnant fossil bivalves from the Isle of Wight
Credit: University of Portsmouth
The fossil belonged to Margaritifera valdensis, an ancient freshwater shellfish distantly related to modern freshwater pearl mussels. It was discovered on the Isle of Wight, an area famous for producing Cretaceous-era fossils, including dinosaurs such as Iguanodon.
Researchers described the fossil as a rare “nursery” because it preserved several stages of development inside the shellfish’s gills.
Among the findings were embryo-like cells and more developed larvae, providing what scientists say is a snapshot of reproduction more than 125 million years ago.
Modern freshwater mussels use a surprisingly complex reproductive strategy. Their young develop inside the mother’s gills before being released into the water, where they temporarily attach themselves to fish as part of their life cycle.
“These new fossils demonstrate that this complex reproductive strategy had already evolved by the Early Cretaceous,” researcher Dr. Aleksandra Skawina said in a statement.
The team also uncovered clues about how the ancient shellfish helped its offspring grow.
Tiny mineral deposits preserved within the gills appear to have acted as calcium stores, helping developing larvae build their shells — a process similar to what scientists observe in living freshwater mussels today.
The discovery may also solve a mystery that has puzzled scientists for more than a century.
Researchers found evidence that a dark material known as “molluskite,” first described by British paleontologist Gideon Mantell in the 1800s, is actually made up of fossilized soft tissues and reproductive structures preserved by minerals.
Never miss a story — sign up for PEOPLE’s free daily newsletter to stay up-to-date on the best of what PEOPLE has to offer, from celebrity news to compelling human interest stories.
“We found that this material is actually made up of fossilized soft tissues and reproductive structures that have been exceptionally preserved by minerals,” geochemist Rafael P. Lozano said in a statement.
For scientists, the fossil offers more than just a remarkable snapshot of prehistoric life.
“Not only does this discovery provide a rare glimpse into how ancient freshwater shellfish reproduced, but it also helps explain how these animals successfully adapted to life in rivers and lakes millions of years ago,” Munt said.
“For decades, scientists have searched for direct evidence of reproduction in ancient freshwater mussels, making this find a significant breakthrough in understanding their evolutionary history.”
Read the original article on People