Thalattoarchon is an Ichthyosaur from early Triassic Nevada, USA. It was about 8.6 m long and was one of the earliest apex predators of the ocean after the Permian-Triassic Extinction that could have fed on creatures of similar size to it. It filled an ecological niche similar to killer whales today. It was the second largest marine macropredator, only preceded by the bigger Dunkleosteus around 140 million years earlier. This fearsome ichthyosaur was the first of its kind to have 5 inch, double edged teeth that it could use to kill larger prey than its future relatives like Cymbospondylus.