Nannopterygius

Nannopterygius (meaning "small wing/flipper" in Greek) is an extinct genus of ophthalmosaurid ichthyosaur that lived during the Middle Jurassic to the Early Cretaceous (Callovian to Berriasian stages). Fossils are known from England, Kazakhstan, Russia, and Norway and six species are currently assigned to the genus.

== Description== left|thumb|250px|Nannopterygius yasykovi alongside two ammonites Nannopterygius was small for an ichthyosaur, measuring up to long at maximum. About of this was tail, including a deeply forked and probably homocercal caudal fin. The head is long, with a typical long narrow rostrum. The eyes are large, hence its classification as an ophthalmosaurid, and have a bony scleral ring inside the eye socket. There are at least 60 disc-shaped vertebrae, although owing to the condition of the fossil it is not possible to tell exactly how many there were, showing that Nannopterygius was flexible, agile and probably a fast swimmer. The ribs are long and curved, but do not quite join up. Most of the features are very similar to the close relative Ophthalmosaurus. However, its paddles are much smaller, around for the forepaddles and only for the hindpaddles. This gave it a very streamlined, torpedo-shaped look, but would have made it quite difficult to generate much lift or to turn quickly, making it an inefficient long-distance swimmer but speedy over short distances. It is therefore possible that it was an ambush predator which plunged into shoals of fish quickly in the shallow seas where it lived.