Ichthyosaurus is an extinct genus of ichthyosaur from the Early Jurassic (Hettangian - Sinemurian) of Europe (Belgium, England, Switzerland). It is among the best known ichthyosaur genera, with the Order Ichthyosauria being named after it. Ichthyosaurus was the first complete fossil to be discovered in the early 1800's by Mary Anning in England.

Shonisaurus is the largest genus of ichthyosaur yet been found growing in one species (S. sikkanniensis) to 21 metres (69 ft). Shonisaurus had a long pointed mouth that contained teeth only at the front end. It had a whale-like body, and its flippers were much longer, and narrower than in other ichthyosaurs. All of these features suggest that Shonisaurus may be a relatively specialised offshoot of the main ichthyosaur evolutionary line

Stenopterygius is an extinct genus of ichthyosaur from the Early to Middle Jurassic (Toarcian - Aalenian) from Europe (England, France, Germany, Switzerland and Luxembourg). Maximum length was 4 meters. Stenopterygius was physically similar to the better known Ichthyosaurus, but had a smaller skull and narrower flippers. One famous fossil is that of a mother and baby that died in childbirth (ichthyosaurs were viviparous). This proved that ichthyosaur infants were born tail-first, just like cetaceans, to prevent them from drowning before fully clearing the birth canal.