Megapterygius

Megapterygius had rear flippers that were even longer than its front flippers, a feature only seen in one other mosasaur, Tylosaurus.1

Its flippers were longer than its skull, which is unique among mosasaurs with paddle-like limbs.1

The shape of its backbone suggests it had a dorsal fin, like a dolphin or shark, which would have helped it turn quickly in the water.12

Its skull was slightly wide around the eye sockets, giving it binocular vision that helped it hunt prey. This is only the second mosasaur known to have this ability.1

The fossil was found in 2006 by Akihiro Misaki, who was actually looking for ammonite fossils when he spotted a vertebra.12

More than 100 shark teeth were found around the Megapterygius skeleton, suggesting that sharks scavenged its body after it died.1

Megapterygius is the most complete mosasaur skeleton ever found in Japan or the northwestern Pacific.2