Gonorynchiformes
Order of fishes
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Through Ocean and Fresh water
Gonorynchiformes have small mouths and no teeth. They are the sole group in the clade Anotophysi, a subgroup of the superorder Ostariophysi. They are characterized by a primitive Weberian apparatus formed by the first three vertebrae and one or more cephalic ribs within the head. This apparatus is believed to be a hearing organ, and is found in a more advanced and complex form in the related cypriniform fish, such as carp. Also like the Cypriniformes, the Gonorynchiformes produce a substance from their skin when injured that dissolves into the water and acts an alarm signal to other fish.
Etymology
The name comes from Ancient Greek γωνία (gōnía), meaning "angle", ῥύγχος (rhúnkhos), meaning "snout", and Latin formes, meaning "form".
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Taxonomy
Although many of the families are rather small, there are several fossil genera. This listing of the groups of Gonorynchiformes includes fossil fish with a short description. They are listed in approximate order of how primitive their characteristics are.
The 5th edition of Fishes of the World classifies the extant taxa in this order as follows, as does Eschmeyer's Catalog of Fishes:
Order Gonorynchiformes Greenwood, Rosen, Weitzman, and Myers, 1966
- Family Chanidae Günther, 1868 (milkfishes)
- Family Gonorynchidae Richardson, 1848 (beaked sandfishes)
- Family Kneriidae Günther, 1868 (shellears)
- Family Phractolaemidae Boulenger, 1901 (snake mudheads)
Fossil taxa
The following fossil gonorynchiforms are also known:
- Genus †Lecceichthys Taverne, 1998 (Late Cretaceous of Italy)
- Genus †Sorbininardus Taverne, 1999 (Late Cretaceous of Italy)
- Family †Apulichthyidae Taverne, 1997 (Late Cretaceous of Italy)
- Family †Halecopsidae Casier, 1946 (Early Eocene of Europe)