A new species of prehistoric croc has been unearthed in south-east Queensland. Dubbed the 'swamp king', the five-metre long giant ruled the waterways only a few million years ago.
University of Queensland researchers identified the Paludirex Vincenti from fossils first found in the 1980s.
Researcher Jorgo Ristevski said the species was named after Geoff Vincent, who found the giant fossilised skull on Baruŋgam country, near the town of Chincilla.
"In Latin, 'Paludirex' means 'swamp king', and 'Vincenti' honours the late Mr Vincent," said Mr Ristevski.
The fossilised skull was on display in the Queensland Museum for years before it was donated to the Chinchilla Museum in 2011.
"The 'swamp king' was one intimidating croc," said Mr Ristevski
"Its fossilised skull measures around 65 centimetres, so we estimate Paludirex Vincenti was at least five metres long."
For context, the largest crocodylian today is the Indo-Pacific crocodile, Crocodylus porosus, which grows to about the same size. But Paludirex had a broader, more heavy-set skull.
"It would've resembled an Indo-Pacific crocodile on steroids," said Mr Ristevski.
A few million years ago, Paludirex was one of Australia's top predators - hunting giant prehistoric marsupials and megafauna.
"The waterways of the Darling Downs would once have been a very dangerous place because of it," said Mr Ristevski.
Mr Ristevski's supervisor, Dr Steve Salisbury, said there were quite a few different kinds of prehistoric crocodylians on this continent.
"Crocs have been an important component of Australia's fauna for millions of years," said Dr Salisbury.
"But the two species we have today — Crocodylus porosus and Crocodylus johnstoni — are only recent arrivals, and were not part of the endemic croc fauna that existed here from about 55 million years ago.
Dr Sailsbury said it is unknown if Paludirex Vincenti went extinct as a result of competition with species like Crocodylus porosus.
"The alternative is that it went extinct as the climate dried, and the river systems it once inhabited contracted – we're currently investigating both scenarios."