Temnodontosaurus was one of the largest ichthyosaurs. Estimates of the maximum length of Temnodontosaurus have ranged from 30ft to 40ft). The largest length estimates rival those of another giant ichthyosaur, Shonisaurus popularis, which was previously considered the largest ichthyosaur.
Temnodontosaurus is known for its incredibly large eyes which, at approximately 20 cm in diameter, are believed to be the largest of any known animal. It possessed a tail bend which was characteristic of Jurassic ichthyosaurs and had many conical teeth filling its jaw that were set in a continuous groove.