The Esocoidei () is a small

suborder Order () is one of the eight major hierarchical taxonomic ranks in Linnaean taxonomy. It is classified between family and class. In biological classification, the order is a taxonomic rank used in the classification of organisms and recognized ...

of freshwater

ray-finned fish Actinopterygii (; ), members of which are known as ray-finned fish or actinopterygians, is a class of bony fish that comprise over 50% of living vertebrate species. They are so called because of their lightly built fins made of webbings of sk ...

, one of two suborders in the order

Salmoniformes Salmoniformes (, lit. "salmon-shaped") is an Order (biology), order of Actinopterygii, ray-finned fishes native to the temperate and subarctic Northern Hemisphere. It contains two suborders: Salmonoidei (containing only the Salmonidae) and Esocoi ...

. It contains two families, Umbridae and

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

. The pikes of genus ''

Esox ''Esox'' is a genus of freshwater fish commonly known as pike or pickerel. It is the type genus of the family (biology), family Esocidae. The type species of the genus is ''Esox lucius'', the northern pike. ''Esox'' have a fossil record exten ...

'' give the order its name. This order is closely related to the Salmonoidei, the two comprising the order Salmoniformes. The esociform fishes first appeared in the late

Cretaceous The Cretaceous ( ) is a geological period that lasted from about 143.1 to 66 mya (unit), million years ago (Mya). It is the third and final period of the Mesozoic Era (geology), Era, as well as the longest. At around 77.1 million years, it is the ...

— early products of the

Euteleostei Euteleostei, whose members are known as euteleosts, is a clade of bony fishes within Teleostei that evolved some 240 million years ago, although the oldest known fossil remains are only from the Early Cretaceous. It is divided into Protacanthopt ...

radiation of that time. They diverged from their sister group

about 110 million years ago, with the extant species having evolved from a common ancestor that lived about 90 million years ago. Today, they are found in weed-choked freshwater habitats in

North America North America is a continent in the Northern Hemisphere, Northern and Western Hemisphere, Western hemispheres. North America is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South Ameri ...

and northern

Eurasia Eurasia ( , ) is a continental area on Earth, comprising all of Europe and Asia. According to some geographers, Physical geography, physiographically, Eurasia is a single supercontinent. The concept of Europe and Asia as distinct continents d ...

Taxonomy

In the past, they were often placed in the order Salmoniformes as the suborder Esocoidei. During the early 21st century, due to their morphological divergence from Salmoniformes, they were instead treated as their own order, Esociformes. However, as phylogenetic studies have increasingly affirmed the relationship of Salmoniformes and Esociformes, more recent taxonomic authorities have revived the old classification of placing esocoids as a suborder of the Salmoniformes. The following families are placed in this group: * Suborder Esocoidei ** Family

Rafinesque Constantine Samuel Rafinesque-Schmaltz (; 22 October 178318 September 1840) was a French early 19th-century polymath born near Constantinople in the Ottoman Empire and self-educated in France. He traveled as a young man in the United States, ult ...

, 1815 - pikes *** Subfamily Dalliinae

Jordan Jordan, officially the Hashemite Kingdom of Jordan, is a country in the Southern Levant region of West Asia. Jordan is bordered by Syria to the north, Iraq to the east, Saudi Arabia to the south, and Israel and the occupied Palestinian ter ...

, 1885 - blackfishes *** Subfamily Esocinae Rafinesque, 1815 - pikes ** Family Umbridae Bonaparte, 1845 - mudminnows Several esocid genera are known from the

Late Cretaceous The Late Cretaceous (100.5–66 Ma) is the more recent 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 ''cre ...

of North America, including †'' Estesesox'' Wilson, Brinkman & Neuman, 1992, †'' Oldmanesox'' Wilson, Brinkman & Neuman, 1992, †'' Archaeosiilik'' Brinkman ''et al.'', 2025 & †'' Nunikuluk'' Brinkman ''et al.'', 2025. Their presence makes esocids one of the few North American freshwater teleost groups to have diversified prior to the Cretaceous-Paleogene extinction event. The three extant esocid genera (''

'', '' Novumbra'', and '' Dallia'') 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. '' Umbra'' remains the only extant genus in the family Umbridae, 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 (geology), epoch that lasted from about 66 to 56 mya (unit), million years ago (mya). It is the first epoch of the Paleogene Period (geology), Period in the modern Cenozoic Era (geology), ...

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

and earliest half of the

Paleogene The Paleogene Period ( ; also spelled Palaeogene or Palæogene) is a geologic period and system that spans 43 million years from the end of the Cretaceous Period Ma (million years ago) to the beginning of the Neogene Period Ma. It is the fir ...

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 Salmoniformes Extant Campanian first appearances