Saurichthys (from , 'lizard' and 'fish') is an extinct genus of predatory ray-finned fish from the Triassic period. It type genus family Saurichthyidae (Changhsingian-Middle Jurassic), and the largest and longest lasting genus in the family. This family also includes the Permian Eosaurichthys (China) and the Jurassic Saurorhynchus (= Acidorhynchus) from Europe and North America, though it may be more appropriate to treat these as subgenera of Saurichthys, due to the genus Saurichthys otherwise being paraphyletic. Fossils of Saurichthys have been found on all continents except South America and Antarctica. It inhabited both marine and freshwater environments. The oldest fossils of Saurichthys were recovered from the Wordie Creek Formation in East Greenland and are Griesbachian (Induan, Early Triassic) in age. Over 50 species of Saurichthys have been described (see list below). The species differ in size and show variability in their skeletal features. The latter can potentially be ascribed to changes in major developmental genes. The use of subgenera (Eosaurichthys, Costasaurichthys, Lepidosaurichthys, Saurorhynchus, Sinosaurichthys) in the literature reflects differences in morphology between species groups. Several species that were described predominantly in the 19th century are based on fragmentary fossils (often isolated teeth). These are mostly considered invalid species by modern taxonomic standards. Louis Agassiz, who described the type species of Saurichthys in 1834, named it the "lizard fish" because of skeletal features that he thought were intermediate to reptiles and fishes. Their exact phylogenetic position is uncertain, though it is agreed that they are not members of Neopterygii. Historically, they have been seen as close relatives of the Acipenseriformes (which includes living sturgeon and paddlefish), though this has been strongly questioned by modern studies. Appearance Saurichthys was an elongate, streamlined fish, commonly about to long. Some species were only a few decimetres long (e.g. Saurichthys minimahleri), while others could grow up to about in length (specimen from the Middle Triassic of Turkey). Species of Saurichthys had an elongate bodyform superficially similar to the modern garfish. Its dorsal and anal fins were placed opposite each other well back on the body, and the tail was symmetrical (abbreviate diphycercal). These features would have made it a powerful swimmer, and it is presumed to have hunted in a similar way to the pike, attacking from an ambush at high speed. Its jaws were extremely long, making up a third of the total body length, and ended in a sharp, beak-like tip. Two to six