of specimens from the Carnian of Nevada, was long. Norian Shonisauridae are known from both sides of the Pacific. Himalayasaurus tibetensis and Tibetosaurus (probably a synonym) have been found in Tibet. These large (10- to 15-m-long) ichthyosaurs have by some been placed into the genus Shonisaurus. The gigantic Shonisaurus sikanniensis (considered as a shastasaurus between 2011 and 2013) whose remains were found in the Pardonet Formation of British Columbia by Elizabeth Nicholls, has been estimated to be as much as in length—if correct, the largest marine reptile known to date. In the Late Triassic, ichthyosaurs attained the peak of their diversity. They occupied many ecological niches. Some were apex predators; others were hunters of small prey. Several species perhaps specialised in suction feeding or were ram feeders; also, durophagous forms are known. Towards the end of the Late Triassic, a decline of variability seems to have occurred. The giant species seemed to have disappeared at the end of the Norian. Rhaetian (latest Triassic) ichthyosaurs are known from England, and these are very similar to those of the Early Jurassic. A possible explanation is an increased competition by sharks, Teleostei, and the first Plesiosauria. Like the dinosaurs, the ichthyosaurs and their contemporaries, the plesiosaurs, survived the Triassic–Jurassic extinction event, and quickly diversified again to fill the vacant ecological niches of the early Jurassic. Jurassic During the Early Jurassic, the ichthyosaurs still showed a large variety of species, ranging from in length. From this epoch, the original British discoveries were made, so that among ichthyosaurs, their names are the ones most familiar to the general public. Genera include Eurhinosaurus, Ichthyosaurus, Leptonectes, Stenopterygius, and the large predator Temnodontosaurus, along with the basal parvipelvian Suevoleviathan, which was little changed from its Norian ancestors. The general morphological variability had been strongly reduced, however. Giant forms, suction feeders and durophagous species were absent. All of these animals were streamlined, dolphin-like forms, although the more basal animals were perhaps more elongated than the advanced and compact Stenopterygius and Ichthyosaurus. The latter belonged to a parvipelvian subgroup, the Thunnosauria. These were fully adapted to an efficient thunniform locomotion, propelling themselves with the end of the tail only, equipped with a vertical tail fin. Their front flippers had more than five fingers. Another parvipelvian branch was the Eurhinosauria such as Leptonectes and Eurhinosaurus, which were specialised forms having very elongated and pointy snouts. Few ichthyosaur fossils are known from