The skeleton of a giant 100-million-year-old marine reptile has been found in Australia, raising hopes for researchers to uncover important evidence of prehistoric life.

The remains of the 6m-tall young long-necked pleiosaur, also known as an elamsaurus, were found by amateur fossil hunters on a cattle station in Queensland last August.

The elasmosaurs, which were 8 to 10 meters long, lived in the Eromaga Sea, which covered large parts of the Australian inland with 50-meter-deep water about 150 million years ago.

Espen Knutsen, senior curator of palaeontology at the Queensland Museum, likened the discovery to that of the Rosetta Stone - it helped experts decipher the hieroglyphs.

"We have never found a body and a head, and this may be key to the future of research in the field," he said, adding that paleontologists may gain more substantial knowledge about the origin, evolution and ecology of the Cretaceous period in the region.

"Because the neck of pleiosaurs made up 2/3 of them, the head often separated from the body after they died, which made the discovery of an intact fossil very difficult."

Knutsen explained that when an elasmosaurus died, its decomposing body was inflated with gases that caused it to rise to the surface of the water. Often the head was broken off when the carcass fell prey to predators.

The specimen found is in good condition, however, and researchers will perform chemical tests on the teeth, which may provide information about the ecology of the environment it lived in, whether it had migrated during its lifetime, or whether it lived permanently in one place , but also for his diet.

Ancient marine reptiles such as pleiosaurs and ichthyosaurs are not classified as dinosaurs, even though they lived around the same time. Plesiosaurs were descendants of land-dwelling species and therefore lacked gills and had to occasionally surface for air. It remains unknown how long they could remain underwater.