First Fossil of a Freshwater Mosasaur Discovered

Posted on December 19, 2012

Freshwater Mosasaur

Mosasaurs were one of the dominant marine predators during the Late Cretaceous Period. It turns out that mosasaurs were also a feared predator in ancient freshwater rivers. A new mosasaur species discovered in Hungary is the first known mosasaur to have lived in freshwater river environments. You can see an artist's interpretation of the freshwater mosasaur here.

The freshwater lizard, Pannoniasaurus inexpectatus, lived about 84 million years ago. It reached about 20 feet in length. Several fossils were discovered. The researchers say the creature "had limbs like a terrestrial lizard, a flattened, crocodile-like skull, and a tail unlike other known members of the mosasaur family."

The new research was published here journal PLoS One by Laszlo Makadi from the Hungarian Natural History Museum, Hungary and colleagues from the University of Alberta, Canada and MTA-ELTE Lendület Dinosaur Research Group, Hungary.

Makadi said in a release, "The evidence we provide here makes it clear that similar to some lineages of cetaceans, mosasaurs quickly adapted to a variety of aquatic environments, with some groups re-invading available niches in freshwater habitats. The size of Pannoniasaurus makes it the largest known predator in the waters of this paleo-environment."

Michael Caldwell, study co-author and mosasaur expert at the University of Alberta in Canada, told National Geographic, that there were probably freshwater plesiosaurs and freshwater ichthyosaurs as well. We just haven't recovered any evidence of these creatures yet.

Photo: Makadi L, Caldwell MW, Osi A (2012)