Swamp King Crocodile Added To Australia's Extinct Giants


Stephen Luntz

Stephen has a science degree with a major in physics, an arts degree with majors in English Literature and History and Philosophy of Science and a Graduate Diploma in Science Communication.

Freelance Writer

crocodile eye

Modern crocodiles shed no tears for a related, but not ancestral, species that was likely even larger and lived in Australia hundreds of thousands or millions of years ago. Univeristy of Queensland

A newly described extinct species of crocodile was at least as long as its largest modern counterparts, and possibly considerably heftier, just in case your nightmares need a little more material.

Australia was once inhabited by three-tonne wombats, giant kangaroos, and a bird so large it has been nicknamed the "demon duck of doom". Not surprisingly, great beasts cruised the rivers to consume anything unwise enough to venture into the water. In trying to make sense of the Pleistocene crocodilian fossil record, the 19th Century included several finds in the genus Pallimnarchus.


However, more recent discoveries have led paleontologists to reject this, concluding the fossils placed under this name came from species too diverse to be included together. That means all the fragments previously assigned to Pallimnarchus need to be allocated correctly, and species described all over again. University of Queensland PhD student Jorgo Ristevski has stepped into the gap with some pieces of a hefty beast found in south-central Queensland.

In PeerJ Ristevski and co-authors have given the name Paludirex vincenti to a species for which we have two partial skulls and some bits of jaw. “Its fossilised skull measures around 65 centimetres, so we estimate Paludirex vincenti was at least five metres long,” Ristevski said in a statement

Fragments of the skull of Paludirex vincenti, showing just how little paleontologists have to work with when identifying this species. Jorgo Ristevski

Australia's modern-day crocodiles include the saltwater crocodile Crocodylus porosus, the largest of which exceed this length. However, it's worth remembering we only have two fossils from which we can guess P. vincenti's size – it's quite possible we'll find many large specimens with more searching in the area.

Even if that doesn't happen, P. vincenti's skull is broader and, in Ristecski's words, “more heavy-set” than modern crocodiles. Ristevski told IFLScience that without having found any bones from the rest of the body, we can't tell if this indicates it also had a more robust body than its modern counterparts, but it's possible.


“The waterways of the Darling Downs would once have been a very dangerous place because of it,” Ristevski said.

A reconstruction of the size of Pauldirex vincenti and a 1.8m (6 foot) human Jorgo Ristevski

No descendants of Pauldirex survive today; with modern Australian crocodiles being relatively recent arrivals from south-east Asia, Ristevski explained.

The paper also describes another Pauldirex species, P. gracilis, which inhabited Australia's far north in the territory now home to modern crocodiles. However, since this represents a simple shift of genus from Pallimnarchus gracilis, it represents a less significant aspect than the new species description.

Paludirex means swamp king in Latin, while vincenti was chosen to honor Geoff Vincent, who discovered the original skull. With only one specimen, we don't know when or why P. vincenti went extinct, but the Darling Downs where the fossils were found are now far too dry to support crocodiles, suggesting climate change played at least some part in them expiring. Whether Crocodylus's arrival helped bring on the end for Paludirex, or occurred to a continent newly free of competitors for its niche, is unknown.