Australia's Largest Aquatic Reptile Found in Gippsland [PHOTOS]

Scientists have discovered a fossilized tooth of the biggest and oldest aquatic reptile in Australia in Gippsland.

The latest prehistoric find is the first evidence that the carnivore creature known as the pliosaurid, swam in southern Australia's waters millions of years ago. The prehistoric water giant was believed to be five metres in length.

The pilosaurid is longer by three metres compared to the plesiosaur which measures only three metres in length. The plesiosaur also roamed Australia's rivers 120 million years ago during the Cretaceous period.

Erich Fitzgerald, a paleontologist at Museum Victoria, said that the two distinct prehistoric reptiles have not been found to swim in other waterways outside of Australia. Dr. Fitzgerald said that this knowledge is significant because it suggests a more complex ecological setting than scientists first realised.

Ms Fitzgerald believes little is still known in Australia's river systems which indicate a possibility of finding more fossils of prehistoric animals.

Both the plesiosaur and the pliosaurid cannot walk on land because of their large flippers, so they had to remain in water. The prehistoric reptiles could only move along the waterways. Some river systems would have stretched as far as 2,000 kilometres.

Bigger pliosaurids fed on fish and smaller terrestrial animals. They were most likely a top predator during the prehistoric times and may have sometimes fed on small dinosaurs that crossed the river.

The fossil discovery in Gippsland was only part of a tooth. The fossilised tooth measured three centimetres long. Scientists believe the whole tooth must have been twice that length.

The tip of the tooth was originally found in 1994 in a rock rich in sediment remains from an ancient riverbed. Back then, it was dismissed as a crocodile tooth.

After a delicate and lengthy process of extracting the fossil from the rock, the tooth was put into storage.

Until recently, Ms Fitzgerald discovered under microscopic analysis that the fossilised tooth's fine ridges is linked with pliosaurids. University of Oxford's Roger Benson analysed the fossil and backed up Ms. Fitzgerald's discovery.