Fossil of Sea Dwelling Dinosaur the Size of a Bus Found in Russia
A bus-sized sea monster that lived alongside the dinosaurs 130 million years ago has been discovered in Russia. The well-preserved 5 foot-long skull of an extinct reptile was first discovered on the bank of the Volga River in 2002, but until now had not been identified as a new species.
The fossil belongs to a group of marine reptiles called plesiosaur. These predatory creatures lived in the Triassic and Jurassic Period, eventually being wiped out in the same mass extinction event that killed all the dinosaurs 66 million years ago.
The new species was a pliosaur, a type of short-necked plesiosaur that could swim faster than their long-necked relatives, and had huge teeth and powerful jaws—making them one of the top ocean predators at the time.
In a study published in the journal Current Biology on Thursday, an international team of scientists set about identifying the fossil from the Volga River deposits. In it, they show that the fossil is not only a new species, but its unusual features means we may have to rethink the evolution of this group of ancient reptiles altogether.
Researchers estimate the species, which they have called Luskhan itilensis, was around 21 feet long—making it about average-sized. (Pliosaurs range from 5 to 49 feet.)
What was remarkable about the fossil, however, was its mishmash of characteristics from several distinct species. Previously, short-necked plesiosaurs were thought to have been constrained to very specific ecological niches and were generally considered to have been apex predators. The distantly related clade Polycotylidae, on the other hand, was a fast-swimming piscivore.
Luskhan itilensis, the researchers report, has features of both. This indicates evolutionary convergence, where species not closely related develop similar features because they live in similar environments.
The most notable feature was its long, slim rostrum (a beak-like snout), which would have meant it resembled fish-eating creatures like river dolphins far more than other pliosaurs. "This is the most striking feature, as it suggests that pliosaurs colonized a much wider range of ecological niches than previously assumed," lead author Valentin Fischer, lecturer at the Université de Liège, Belgium, said in a statement.