The Esociformes () are a small order of

ray-finned fish Actinopterygii (; ), members of which are known as ray-finned fishes, is a class of bony fish. They comprise over 50% of living vertebrate species. The ray-finned fishes are so called because their fins are webs of skin supported by bony or h ...

, with two families,

Umbridae Umbridae is a family of fish in the order Esociformes, which contains pike, pickerel, and mudminnows. The single living genus, ''Umbra'', occupies weed-choked freshwater habitats in eastern North America and eastern Europe. While the family trad ...

and

Esocidae Esocidae is a family of fish in the order Esociformes, which contains pike, pickerel, and mudminnows. While the family traditionally only contained the genus ''Esox'', recent genetic and paleontological research have recovered ''Novumbra'' and ' ...

. The pikes of genus '' Esox'' give the order its name. This order is closely related to the

Salmoniformes Salmonidae is a family of ray-finned fish that constitutes the only currently extant family in the order Salmoniformes . It includes salmon (both Atlantic and Pacific species), trout (both ocean-going and landlocked), chars, freshwater whitefis ...

, the two comprising the superorder

Protacanthopterygii Protacanthopterygii is a ray-finned fish taxon ranked as a superorder of the infraclass Teleostei. They inhabit both marine and freshwater habitats. They appear to have evolved in the Cretaceous or perhaps late Jurassic, originating probably roug ...

, and are often included in their order. The esociform fishes first appeared in the mid-

Cretaceous The Cretaceous ( ) is a geological period that lasted from about 145 to 66 million years ago (Mya). It is the third and final period of the Mesozoic Era, as well as the longest. At around 79 million years, it is the longest geological period of ...

— early products of the Euteleostei radiation of that time. Today, they are found in weed-choked freshwater habitats in North America and northern

Eurasia Eurasia (, ) is the largest continental area on Earth, comprising all of Europe and Asia. Primarily in the Northern and Eastern Hemispheres, it spans from the British Isles and the Iberian Peninsula in the west to the Japanese archipelago ...

Esocidae

The three extant esocid genera ('' Esox'', '' Novumbra'', and ''

Dallia ''Dallia'' is a genus of mudminnows native to Russia and Alaska Alaska ( ; russian: Аляска, Alyaska; ale, Alax̂sxax̂; ; ems, Alas'kaaq; Yup'ik: ''Alaskaq''; tli, Anáaski) is a state located in the Western United States on ...

'') together comprise a

holarctic The Holarctic realm is a biogeographic realm that comprises the majority of habitats found throughout the continents in the Northern Hemisphere. It corresponds to the floristic Boreal Kingdom. It includes both the Nearctic zoogeographical reg ...

distribution. Two additional genera have been described from fossils dating to the Cretaceous of North America.

Umbridae

Umbra The umbra, penumbra and antumbra are three distinct parts of a shadow, created by any light source after impinging on an opaque object. Assuming no diffraction, for a collimated beam (such as a point source) of light, only the umbra is cast. T ...

'' remains the only extant species in this family, and can be found in eastern North America and Europe. Three additional genera have been described from fossils dating from the

Paleocene The Paleocene, ( ) or Palaeocene, is a geological epoch that lasted from about 66 to 56 million years ago (mya). It is the first epoch of the Paleogene Period in the modern Cenozoic Era. The name is a combination of the Ancient Greek ''pal ...

of Europe; however, genetic studies on the extant species of Umbra have recovered a split between the North American and European species dating to the

Late Cretaceous The Late Cretaceous (100.5–66 Ma) is the younger of two epochs into which the Cretaceous Period is divided in the geologic time scale. Rock strata from this epoch form the Upper Cretaceous Series. The Cretaceous is named after ''creta'', ...

and earliest half of the Paleogene.

Relationships

While the family Esocidae traditionally only contained the genus Esox, recent genetic and paleontological research have recovered ''Novumbra'' and ''Dallia'' as members of the family Esocidae, being closer related to ''Esox'' than ''Umbra''. ''Umbra'' is the only remaining extant species in Umbridae. Various fossils have been described as members of Esociformes and are placed on the following tree accordingly.

References

* {{Taxonbar, from=Q379768 Ray-finned fish orders