The Ellimmichthyiformes, also known as double-armored herrings, are an

extinct Extinction is the termination of an organism by the death of its Endling, last member. A taxon may become Functional extinction, functionally extinct before the death of its last member if it loses the capacity to Reproduction, reproduce and ...

order Order, ORDER or Orders may refer to: * A socio-political or established or existing order, e.g. World order, Ancien Regime, Pax Britannica * Categorization, the process in which ideas and objects are recognized, differentiated, and understood ...

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 ...

known from the

Early Cretaceous The Early Cretaceous (geochronology, geochronological name) or the Lower Cretaceous (chronostratigraphy, chronostratigraphic name) is the earlier or lower of the two major divisions of the Cretaceous. It is usually considered to stretch from 143.1 ...

to the

Oligocene The Oligocene ( ) is a geologic epoch (geology), epoch of the Paleogene Geologic time scale, Period that extends from about 33.9 million to 23 million years before the present ( to ). As with other older geologic periods, the rock beds that defin ...

. They were the

sister group In phylogenetics, a sister group or sister taxon, also called an adelphotaxon, comprises the closest relative(s) of another given unit in an evolutionary tree. Definition The expression is most easily illustrated by a cladogram: Taxon A and ...

to the extant true

herring Herring are various species of forage fish, belonging to the Order (biology), order Clupeiformes. Herring often move in large Shoaling and schooling, schools around fishing banks and near the coast, found particularly in shallow, temperate wate ...

shad The Alosidae, or the shads, are a family (biology), family of clupeiform fishes. The family currently comprises four genera worldwide, and about 32 species. The shads are Pelagic fish, pelagic (open water) schooling fish, of which many are anadr ...

and

anchovies An anchovy is a small, common forage fish of the family Engraulidae. Most species are found in marine waters, but several will enter brackish water, and some in South America are restricted to fresh water. More than 140 species are placed in 1 ...

in the order

Clupeiformes Clupeiformes is the order of ray-finned fish that includes the herring family, Clupeidae, and the anchovy family, Engraulidae and sardines. The group includes many of the most important forage and food fish. Clupeiformes are physostomes, ...

, with both orders belonging to the suborder

Clupeomorpha Clupeomorpha is a superorder of ray-finned fish which belongs to the clade Otocephala. Represented today only by the diverse, economically-important order Clupeiformes (containing herrings, anchovies and allies), it was formerly even more diverse ...

. A highly successful group throughout the

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 ...

, they were found worldwide and are known to have inhabited both marine and freshwater habitats. They appear to have been a largely marine group for most of their history, with the first freshwater lineages appearing during 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 ...

. Shortly after the origin of the Ellimmichthyiformes in the Early Cretaceous, the

Mediterranean The Mediterranean Sea ( ) is a sea connected to the Atlantic Ocean, surrounded by the Mediterranean basin and almost completely enclosed by land: on the east by the Levant in West Asia, on the north by Anatolia in West Asia and Southern ...

portion of the

Tethys Ocean The Tethys Ocean ( ; ), also called the Tethys Sea or the Neo-Tethys, was a prehistoric ocean during much of the Mesozoic Era and early-mid Cenozoic Era. It was the predecessor to the modern Indian Ocean, the Mediterranean Sea, and the Eurasia ...

appears to have been a major center of diversification for them, as the majority of fossils of this group are known from there. Following this, they saw an explosion in diversity during the

Cenomanian The Cenomanian is, in the International Commission on Stratigraphy's (ICS) geological timescale, the oldest or earliest age (geology), age of the Late Cretaceous epoch (geology), Epoch or the lowest stage (stratigraphy), stage of the Upper Cretace ...

, possibly due to the high sea levels of the Tethys at the time and the resulting impact on geography and food distribution, with the group evolving numerous different body plans. However, they were devastated by the

Cretaceous–Paleogene extinction event The Cretaceous–Paleogene (K–Pg) extinction event, also known as the K–T extinction, was the extinction event, mass extinction of three-quarters of the plant and animal species on Earth approximately 66 million years ago. The event cau ...

and saw a drastic reduction in range. Only a few freshwater species in the genera '' Diplomystus'' and '' Guiclupea'' survived primarily 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

China China, officially the People's Republic of China (PRC), is a country in East Asia. With population of China, a population exceeding 1.4 billion, it is the list of countries by population (United Nations), second-most populous country after ...

(although the unusual '' Gasteroclupea'' of

South America South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a considerably smaller portion in the Northern Hemisphere. It can also be described as the southern Subregion#Americas, subregion o ...

appears to have briefly survived into 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), ...

), including '' Diplomystus dentatus'' of the famous

Green River Formation The Green River Formation is an Eocene geologic formation that records the sedimentation in a group of intermountain lakes in three basins along the present-day Green River (Colorado River), Green River in Colorado, Wyoming, and Utah. The sedimen ...

. A few marine lineages survived in the

near modern

Italy Italy, officially the Italian Republic, is a country in Southern Europe, Southern and Western Europe, Western Europe. It consists of Italian Peninsula, a peninsula that extends into the Mediterranean Sea, with the Alps on its northern land b ...

, such as "''Diplomystus''" ''trebicianensis'' in the Paleocene and '' Eoellimichthys'', the last marine ellimmichthyiform, during the

Eocene The Eocene ( ) is a geological epoch (geology), epoch that lasted from about 56 to 33.9 million years ago (Ma). It is the second epoch of the Paleogene Period (geology), Period in the modern Cenozoic Era (geology), Era. The name ''Eocene'' comes ...

. The last surviving ellimmichthyiform, ''Guiclupea'', was a freshwater species that occurred in southern China during the

, representing the youngest member of the group.''''

Taxonomy

The following families are known: * Genus ?†'' Ornategulum'' Guiclupea superstes

* Suborder †Armigatoidei ** Family † Armigatidae ***Genus †'' Armigatus'' Rhombichthys intocabilis

*** Genus †'' Diplomystus'' *** Genus †'' Guiclupea'' *** Genus †'' Horseshoeichthys'' * Suborder †Ellimmichthyoidei ** Family † Paraclupeidae *** Genus †'' Caboellimma'' *** Genus †'' Codoichthys'' *** Genus †'' Ellimma'' *** Genus †''

Ellimmichthys ''Ellimmichthys'' is an extinct genus of freshwater Otocephala, clupeomorph fish belonging to the order Ellimmichthyiformes, of which it is the type genus. It was a distant relative of modern herrings and Anchovy, anchovies. It inhabited freshwat ...

'' *** Genus †'' Eoellimmichthys'' *** Genus †'' Foreyclupea'' *** Genus †'' Ezkutuberezi'' *** Genus †'' Kwangoclupea'' *** Genus †'' Paraclupea'' *** Genus †'' Ranulfoichthys'' *** Genus †'' Rhombichthys'' *** Genus †'' Scutatoclupea'' *** Genus †'' Scutatuspinosus'' *** Genus †'' Thorectichthys'' *** Genus †'' Tunisiaclupea'' *** Genus †'' Tycheroichthys'' * Suborder †Sorbinichthyoidei ** Family † Sorbinichthyidae *** Genus †'' Sorbinichthys'' ** Family † Gasteroclupeidae *** Genus †'' Gasteroclupea'' Other studies have found this division of families to be

paraphyletic Paraphyly is a taxonomic term describing a grouping that consists of the grouping's last common ancestor and some but not all of its descendant lineages. The grouping is said to be paraphyletic ''with respect to'' the excluded subgroups. In co ...

References

{{herrings, state=expanded Prehistoric ray-finned fish orders Otocephala Valanginian first appearances Chattian extinctions