Palaeonisciformes

…were those of the order Palaeonisciformes, a label derived from a Greek word meaning “ancient scale.” Like the living members of Chondrostei, the order Palaeonisciformes is not a natural group but rather a series of families connected by interrelationships that are poorly understood. These fishes possessed essentially the same feeding…

Palaeonisciformes often had large eyes placed far forward, long mouths with the upper jaw firmly bound to the fully armoured cheek, and a relatively weak lower jaw muscle. They gave rise to a great variety of types, with elongate bodies and jaws, bottom-living types that…

…group of fishes called the palaeonisciforms, which appeared at the end of the Silurian Period (about 419 million years ago). The genera Acipenser, Huso, Scaphirhynchus, and Pseudoscaphirhynchus contain living species of sturgeons.