The Amiiformes /ˈæmi.ɪfɔːrmiːz/ order of fish has only one extant species, the bowfin (Amia calva). These Amiiformes are found in the freshwater systems of North America, in the United States and parts of southern Canada. They live in freshwater streams, rivers, and swamps.
Bowfins are not on the endangered list. They have the ability to go to the surface to breathe air if the water level is too low. Characteristics of Amiiformes are a cylindrical body with a long dorsal fin, single gular plate, heterocercal caudal fin, 10 to 13 flattened branchiostegal rays, maxilla included in gape, and prominent ocellus near upper base of caudal fin.
The extinct species of the Amiiformes can be found as fossils in Asia and Europe, but the bowfin is the last living species in the order. Amiiformes is therefore the last surviving order of Halecomorphi, the clade to which the bowfin and its fossil relatives belong. Other orders, such as the Parasemionotiformes, are all extinct.
Halecomorphs, and its sister group Ginglymodi, belong to Holostei. Holosteans are the sister group of teleosteans, the group to which nearly all (i.e., 96%) living fishes belong to. Holosteans and Teleosts form a clade called Neopterygii. The following cladogram[2] summarizes the evolutionary relationships of living and fossil Halecomorphs, and other neopterygians.
Amiiformes likely originated in the western Tethys Ocean, in what is now Europe. The oldest member of the Amiiformes is Caturus heterurus from the lower Lias (Sinemurian) of England. Amiiformes had spread to North America and Africa by the end of the Middle Jurassic, reaching an apex of diversity during the Early Cretaceous, during the Late Cretaceous and Cenozoic, the group declined until only a single species, the bowfin remained.[3]