Fossilised animal sperm is world’s oldest

● A tiny sea creature trapped in amber 100 million years ago had newly mated

The world’ s oldest animal sperm has been found in tiny water beasts that were trapped in amber around 100 million years ago.

The discovery was made by researchers from the Queen Mary University of London and the Chinese Academy of Science in Nanjing.

They discovered the sperm in a newly identified species of crustacean which has been preserved inside a piece of amber – fossilised tree resin – that was formed during the Cretaceous period.

It’ s believed the animals, which has been named Myanmarcypris hui, had sex just before their entrapment in the amber.

Specimens of fossilised sperm are exceptionally rare.

The oldest previously known examples are around 17 million years old.

My an marc y pr ishui is an o st ra cod–a kind of crustacean that has existed for 500 million years and lives in all kinds of aquatic environments, from deep oceans to lakes and rivers.

Fossilise do st ra cod shells are common and abundant but finding specimens preserved in ancient amber with their appendages and internal organs intact provides a rare opportunity to learn more about their evolution.

Professor Dave Horne, professor of micro palaeontology at Queen Mar y University of London, said: “Analyses of fossil ostracod shells are hugely informative about past environments and climates, as well as shedding light on evolutionary puzzles, but exceptional occurrences of fossilised soft parts like this result in remarkable advances in our understanding.”

During the Cretaceous period– when dinosaurs such as Tyrannosaurus rex still roamed the planet –the ostracods were likely to have been living in a coastal lagoon fringed by trees in what is now Myanmar when they became trapped in a blob of resin –frozen in time.

Using X-ray microscopy the team created computer-aided 3D reconstructions of the ostracods, which measure less than 1mm long, embedded in the amber.

“The results were amazing – not only did we find their tiny appendages to be preserved inside their shells, we could also see their reproductive organs,” He Wang said.

“But when we identified the sperm inside the female, and knowing the age of the amber, it was one of those special ‘eureka’ moments in a researcher’s life”.

Myanmar amber has previously yielded other groundbreaking pre historic finds, including frogs, snakes and a feathered dinosaur tail.

Bo Wang, of the Chinese Academy of Science, added:

“Hundreds of new species have been described in the past five years, and many of them have made evolutionary biologists re - consider longstanding hypotheses on how certain line ages developed and how ecological relationships evolved.”

The team found adult males and females within the amber, but it was a female specimen that contained the sperm– indicating that it must have mated shortly before becoming trapped in the amber.