First freshwater 'gigantic marine lizards' discovered
New fossils discovered in Hungary belong to the first known mosasaur that lived in freshwater river environments similar to modern freshwater dolphins, according to new research.
The species lived about 84 million years ago, the largest specimens reached about 20 feet in length, and belongs to a family called 'mosasaurs', conventionally thought of as gigantic finned marine lizards, similar and perhaps even related to present day monitor lizards.
Laszlo Makadi from the Hungarian Natural History Museum, Hungary and colleagues from the University of Alberta, Canada and MTA-ELTE Lend and #65533;let Dinosaur Research Group, Hungary discovered several fossils of the new species, ranging from small juveniles to large adults that suggest that this species had limbs like a terrestrial lizard, a flattened, crocodile-like skull, and a tail unlike other known members of the mosasaur family.
The fossils were recovered from an open-pit mine in the Bakony Hills of Western Hungary, which were once flood-plains.
According to the study, this is the first known mosasaur that lived in freshwater, and only the second specimen of a mosasaur to have been found in rocks that were not once deposited in the ocean.
"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," Makadi said.
Even in the modern world, scaly reptiles in the aquatic world are extremely rare. Only a few species live in the water, and even fewer, like marine iguanas and sea kraits, live in the oceans.
The new species described here probably adapted to freshwater environments similarly to river dolphins, such as those now inhabiting the Amazon, Ganges and Yangtze rivers.
The discovery has been detailed in the open-access journal PLOS ONE.