The fossil of a 7.1-metre marine reptile unearthed in outback Queensland will soon be donated to an outback museum.

A small bone was first discovered in 2023 by fossil enthusiast Cassandra Prince on a property about 400 kilometres north-west of Longreach.

A careful excavation of the site subsequently revealed what is believed to be the most complete fossil of an ichthyosaur ever found in Australia.

“I was very confident the rest of the body was down under the dirt,” Prince said.

The fossil, believed to be about 90 per cent intact, consists of a complete vertebral column, an intact left flipper, partial right flipper, rare hind flippers, partial tail fin and nearly complete skull and torso.

“We’re thinking he’s lost a flipper but it may be laying down the side there,” she said.

The ichthyosaur has been donated to the Australian Age of Dinosaurs Museum of Natural History in Winton, a region of central-west Queensland renowned for dinosaur fossil discoveries.

Museum founder David Elliott said the find was “extremely rare”.

“Skulls are relatively common or partial skulls or partial bodies, but to get the whole animal all in place is so rare,” Elliott told 9News.

“So, now you can look at that and know its exact proportions, you know, the proportion of the skull, of the tail to the length and all that.

“This is a first for us, you know, and it had to happen sooner or later, so it’s finally happened.”

Ichthyosaurs, now extinct, were dolphin-like marine reptiles that were a dominant predator of Australia’s inland sea during the early Cretaceous period more than 100 million years ago.