Scientists solve the mystery of 237-million-year-old sea creature

Two strange skeletons found in China more than 20 years ago have helped scientists identify an animal unlike any amphibian alive today.

The fossils were collected by local farmers in Guizhou Province in China in 2004.

They belonged to a previously unknown species that lived around 237 million years ago, during the Triassic Period, when dinosaurs were beginning to appear.

Scientists have named it Gerrothorax maritimus, with 'maritimus' meaning 'of the sea'.

The creature was an early relative of modern amphibians, such as frogs, newts and salamanders - however, scientists think it may have lived entirely in the ocean.

Amphibians usually live on land or in fresh water.

None of the amphibian species alive today spend their whole life in the sea because their thin skin would struggle to cope with salty sea water.

But, scientists think Gerrothorax maritimus may have lived entirely in the ocean.

The two almost-complete skeletons were found in rocks formed at least 30 kilometres from the nearest island.

Their bones were still joined together, making it unlikely that the bodies had been washed out to sea from land. Chemical clues inside the fossils also matched the seawater from that time.

The larger animal was nearly 74cms long, about the length of a small guitar.

It had a wide, flattened body covered with plates of bone, like armour.

Scientists think this covering may have protected it from predators and helped its body cope with salty water. It also had gills for breathing underwater.

Its broad mouth suggests it waited on the seabed before quickly sucking in passing prey, a little like some sharks do today.

However, soft parts such as skin and organs were not preserved, so there is still plenty that scientists do not know.

The discovery provides the strongest evidence yet that at least one ancient amphibian relative adapted to life in the open sea.

The research was published in the scientific journal Nature Ecology & Evolution.