72-Million-Year-Old Mosasaur Unearthed in Japan; Ancient Predator as Large as Great White Shark Terrorized Pacific Seas

Millions of years ago, the Pacific seas were prowled by a predator which belonged to a group of large marine reptile species. Now, the petrified remains of this aquatic monster were unearthed by researchers from the University of Cincinnati.

Japanese Blue Dragon

While searching for ammonite fossils for his doctorate thesis, Akihiro Misaki discovered an intriguing dark fossil in the sandstone in 2006. Upon closer examination, it was found to be a vertebra which is part of a nearly complete fossil of an ancient apex predator. The specimen was unearthed along the Aridagawa River in Wakayama Prefecture, Japan.

The specimen was considered as the most complete skeleton of a giant marine reptile ever found in Japan or the northwestern Pacific. It went through further investigation under UC Associate Professor Takuya Konishi and his international colleagues.

Experts categorized the animal in the subfamily Mosasaurinae and named it Megapterygius wakayamaensis. Japanese researchers called it the Wakayama Soryu (blue dragon), after the place of its discovery. In China, dragons are mythical creatures that live in the sky and make thunder, but they are portrayed as aquatic creatures in Japanese folklore.

The air-breathing creature about the size of a bus was warm blooded, but it was not a mammal. It was also not a crocodile despite having a similar shaped head. Instead, the colossal animal belonged to a group of extinct aquatic reptiles called mosasaurs. The Wakayama blue dragon has some characteristics that are similar to mosasaurs discovered in New Zealand and other features comparable to those found in California.

The giant predator had binocular vision and four enormous limbs. It also had extra-long rear flippers which might have aided propulsion along with its long finned tail. Unlike other large extinct marine reptiles, the mosasaur had a dorsal fin like that of a shark which could have helped it turn in the water quickly and precisely.

Konishi suggests that the blue dragon's large paddle-shaped flippers might have been used for movement, although that type of swimming would be uncommon among mosasaurs and virtually all other animals. Experts lack any modern analog for this kind of body morphology, since no animal uses four large flippers in conjunction with a tail fin. This discovery has therefore opened new challenges in understanding how mosasaurs swim.

Mosasaurs: Predatory Marine Lizards

Mosasaurs were prehistoric creatures which lived about 100 million to 66 million years ago. They are considered as one of the greatest predators of all time, measuring up to 56 feet (17 meters).

For several millions of years, these fearsome beasts reigned supreme in the Pacific ocean as the last of the great marine lizards. Their powerful jaws and sharp teeth allowed them to take on just about anything, including shellfish, turtles, and sharks. It was also suggested that they could have also eaten others of their kind.

These colossal marine reptiles were contemporaries of Tyrannosaurus rex and other dinosaurs which ruled the Earth during the late Cretaceous era. They were victims of the same mass extinction which killed nearly all dinosaurs when the Gulf of Mexico was struck by an asteroid.