Dr. Ryan Thalattoarchon Saurophagis

Thalattoarchon saurophagis—translates to "lizard-eating sovereign of the sea. It was at least 28 feet (8.6 meters) long and lived about 244 million years ago during the Triassic period.The bus-size beast was an early ichthyosaur, part of a group of reptiles that swam the world's seas during the dinosaur era.

The Thalattoarchon fossil, partially dug up in 1998, was unusually well preserved, including the skull, fins, and entire vertebral column. Which is pretty amazing, particularly for an animal this size. In 2010, a group of archaeologists returned to the Nevada site to dig up the rest of the fossil. 

In the process, the scientists discovered an enormous skull and jaw-laden with large, sharp teeth that are big enough to carve up other large marine reptiles. Thalattoarchon's modern relatives would be orcas and great white shark both of which will take on similar-size prey. 

The sea monster's discovery also shows how ecosystems can bounce back from even the most extreme events.This animal occurs only eight million years after the biggest mass extinction event in Earth's history, The Permian extinction (which literally wiped out up to 95 percent of all the species in the ocean). "The ocean was a pretty empty place afterward."