Alberta scientist finds massive crocodile-like fossil in Hungarian lake
It grew up to six metres long and its toothy mouth and crocodile-like body was the terror of ancient rivers and shorelines many millions of years ago.

Most mosasaurs were giant undersea predators, some growing up to 16 metres long, which breathed air but were full-time, fearsome sea creatures complete with paddle-like limbs similar to those of a whale. They lived around the same time as the dinosaurs and have been called the T. Rex of the sea.

“They were much bigger than T. Rex,” said Caldwell, an expert in mosasaurs. “They really were sea monsters.” (Tibor Pecsics)

The freshwater mosaur, Pannoniasaurus (2012)

Phylum : Chordata
Class : Reptilia
Order : Squamata
Family : Mosasauridae
Subfamily : Tethysaurinae
Genus : Pannoniasaurus
Species : P. inexpectatus

  • Late Cretaceous (85,3 - 83,5 Ma)
  • 6 m long (size)
  • Hungary (map)

In 1999, a vertebra was discovered alongside a variety of fish and crocodile teeth in a waste dump of a coal mine in an industrial town in Western Hungary. This was the first known specimen of this mosasaur, named Pannoniasaurus inexpectatus. In 2000, in a dried-up river system, more fragmentary vertebrae of P. inexpectatus were found. The fossils were so fragmentary that they were mistaken for the bones of large terrestrial lizards.

It wasn’t until the recent discovery of more bones, including the all-important skull bones, that paleontologists realized that they had been piecing together a very unusual species of ancient aquatic reptile. The researchers have now collected over 100 P. inexpectatus bones from large and small individuals.

P. inexpectatus lived between 85.8 to 83.5 million years ago, during the Late Cretaceous period. It thrived in the freshwater river system in the western Tethyan Archipelago, a series of island chains that sat between the African and Eurasian landmasses in the Tethys Ocean.

The scientists think that P. inexpectatus could have grown up to six meters in length, making it the largest aquatic predator of its environments. It was apparently specialized for its freshwater environment, having a flattened skull like a crocodile for ambushing prey on land and in shallow water and possibly limbs like a terrestrial lizard. The scientists believe Pannoniasaurus adapted to the freshwater environment much like modern river dolphins adapted to life in the Amazon, Ganges, Yangtze and La Plata River.

From National Geographic:

Ancient Sea Monster Found—First Freshwater Species Known
Crocodile-like predator roamed rivers 84 million years ago, study says.

It’s not quite Nessie, but it’s close. Fossils belonging to an 84-million-year-old freshwater sea monster have been found in Hungary, according to a new study.

The recently unearthed creature belongs to a family of ancient aquatic reptiles known as mosasaurs, which looked like crosses between crocodiles and whales. Mosasaurs lacked the superlong necks found in plesiosaurs, which the legendary inhabitant of Loch Ness is alleged to be.

Dubbed Pannoniasaurus, the creature is the first mosasaur thought to spend its entire life in freshwater.

“The evidence we provide here makes it clear that similar to some lineages of [whales], mosasaurs quickly adapted to a variety of aquatic environments,” study leader László Makádi, a paleontologist at the Hungarian Natural History Museum, said in a statement

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Illustration: A mosasaur swims an ancient river in an artist’s rendering by Tibor Pecsics
Article by Ker Than, National Geographic News; December 19, 2012