Thalattoarchon is certainly one of the oldest Triassic ichthyosaur but also the first large marine predators marine reptiles at the top of the food chain (occupying the same ecological niche as pliosaur the Jurassic and Cretaceous Tylosaurus). If it looks like cymbospondylus physically he is differentiated by that large head and teeth. These are not made to catch fish but to shred the flesh and muscle from other marine reptiles. This big predator hunting prey like Nothosaurus and Ichthyosaurs such as cymbospondylus.
Thalattoarchon was in the documentary "ancient sea monster", under the title "Sharp Tooth" ichthyosaur where he attacked big fish and other ichthyosaurs.