Ichthyodectiformes is 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 of marine stem-

teleost Teleostei (; Ancient Greek, Greek ''teleios'' "complete" + ''osteon'' "bone"), members of which are known as teleosts (), is, by far, the largest group of ray-finned fishes (class Actinopterygii), with 96% of all neontology, extant species of f ...

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 ...

. The order is named after the genus ''

Ichthyodectes ''Ichthyodectes'' is an extinct genus of ichthyodectid ray-finned fish which lived during the Late Cretaceous. Fossils of the species included have been found from Canada to Texas. Description ''Ichthyodectes ctenodon'' ("fish biter with comb ...

'', established by

Edward Drinker Cope Edward Drinker Cope (July 28, 1840 – April 12, 1897) was an American zoologist, paleontology, paleontologist, comparative anatomy, comparative anatomist, herpetology, herpetologist, and ichthyology, ichthyologist. Born to a wealthy Quaker fam ...

in 1870. Ichthyodectiforms are usually considered to be some of the closest relatives of the teleost

crown group In phylogenetics, the crown group or crown assemblage is a collection of species composed of the living representatives of the collection, the most recent common ancestor of the collection, and all descendants of the most recent common ancestor ...

. They were most diverse 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 ...

period, though basal forms like ''

Thrissops ''Thrissops'' (from , 'hair' and 'look') is an extinct genus of stem-teleost fish from the Jurassic period (Kimmeridgian to Tithonian). Its fossils are known from the Solnhofen Limestone, as well as the Kimmeridge Clay. ''Thrissops'' was a fa ...

Occithrissops ''Occithrissops'' is an extinct genus of ray-finned fish of the Jurassic, described from Sundance Formation. The genus name of ''Occithrissops'' refers to the occidental occurrence of the genus and its relationship to '' Thrissops''. Description ...

'' and ''

Allothrissops ''Allothrissops'' is an extinct genus of marine ray-finned fish in the order Ichthyodectiformes, or bulldog fish. It is known from the Late Jurassic The Late Jurassic is the third Epoch (geology), epoch of the Jurassic Period, and it spans th ...

'' are known from the Middle-

Late Jurassic The Late Jurassic is the third Epoch (geology), epoch of the Jurassic Period, and it spans the geologic time scale, geologic time from 161.5 ± 1.0 to 143.1 ± 0.8 million years ago (Ma), which is preserved in Upper Jurassic stratum, strata.Owen ...

of Europe and North America. They were almost entirely wiped out by the Cretaceous-Paleogene extinction event, but a single species, '' Saurocephalus lanciformis'', appears to have survived into the earliest

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), ...

(

Danian The Danian is the oldest age or lowest stage of the Paleocene Epoch or Series, of the Paleogene Period or System, and of the Cenozoic Era or Erathem. The beginning of the Danian (and the end of the preceding Maastrichtian) is at the Cretac ...

). Most ichthyodectiforms ranged between in length. Most of known

taxa In biology, a taxon (back-formation from ''taxonomy''; : taxa) is a group of one or more populations of an organism or organisms seen by taxonomists to form a unit. Although neither is required, a taxon is usually known by a particular name and ...

were

predator Predation is a biological interaction in which one organism, the predator, kills and eats another organism, its prey. It is one of a family of common List of feeding behaviours, feeding behaviours that includes parasitism and micropredation ...

s, feeding on smaller fish; in several cases, larger ichthyodectiforms preyed on smaller members of the order. Some

species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...

had remarkably large teeth, though others, such as ''

Gillicus arcuatus ''Gillicus'' was a relatively small, long ichthyodectiform ray-finned fish that lived in central North America (Western Interior Seaway), Europe and East Asia, from the late Albian to the early Maastrichtian. Description Like its larger rela ...

'', had small ones and sucked in their prey. '' Heckelichthys preopercularis'' is a rare example of non-predatory ichthyodectiform, more likely to be microphagous, fed on small particles. There is evidence that at least one species, ''

Xiphactinus audax ''Xiphactinus'' (from Latin and Greek for "sword-ray") is an extinct genus of large predatory marine ray-finned fish that lived during the late Albian to the late Maastrichtian. The genus grew up to in length, and superficially resembled a garga ...

'', may have been

endotherm An endotherm (from Greek ἔνδον ''endon'' "within" and θέρμη ''thermē'' "heat") is an organism that maintains its body at a metabolically favorable temperature, largely by the use of heat released by its internal bodily functions inst ...

ic ("warm-blooded"). Another genus, '' Dugaldia'', may have been able to laterally open its mouth extremely wide in a manner akin to the modern

sarcastic fringehead The sarcastic fringehead (''Neoclinus blanchardi'') is a small but hardy saltwater tube-blenny that possesses a large mouth and aggressive territorial behavior, for which it has been given its common name. The term 'fringehead' reflects the disti ...

Systematics

The basal phylogeny is badly resolved, leading to many ichthyodectiforms that are simply known to be rather primitive, but where nothing certain can be said about their precise relationships. Ichthyodectiformes * '' Africathrissops'' Taverne, 2010 * ''

'' Nybelin, 1964 * '' Antarctithrissops'' Arratia ''et al.'', 2004 * '' Ascalabothrissops''? Arratia, 2000 * '' Capassoichthys'' Taverne, 2015 * '' Carsothrissops'' d'Erasmo, 1946 * '' Dugaldia'' Lees, 1990 * '' Faugichthys'' Taverne & Chanet, 2000 * '' Furloichthys'' Taverne & Capasso, 2018 * ''

'' Schaeffer & Patterson, 1984 * '' Ogunichthys'' Alvarado-Ortega & Brito, 2009 * '' Pachythrissops''? Woodward, 1919 * '' Prymnetes'' Cope, 1871 * ''

'' Agassiz, 1843 * '' Sultanuvaisia'' Nesov, 1981 * '' Unamichthys'' Alvarado-Ortega, 2004 * '' Verraesichthys'' Taverne, 2010 * Chuhsiungichthyidae? Yabumoto, 1994 ** '' Chuhsiungichthys''? Lew, 1974 ** '' Jinjuichthys''? Kim ''et al.'', 2014 ** '' Mesoclupea''? Ping & Yen, 1933 * Bardackichthyidae? Hacker & Shimada, 2021 ** '' Bardackichthys''? Hacker & Shimada, 2021 * Cladocyclidae Maisey, 1991 ** ''

Aidachar ''Aidachar'' (named for Aydahar, a mythical Kazakh dragon) is an extinct genus of marine ichthyodectiform ray-finned fish from the Late Cretaceous (Cenomanian-Turonian) of Central Asia and North Africa. The type species is ''A. paludalis'', ...

'' Nesov, 1981 ** ''

Chirocentrites ''Chirocentrites'' is an extinct genus of marine ray-finned fish in the order Ichthyodectiformes. It contains a single species, ''C. coroninii'', from the Late Cretaceous (Cenomanian) of Slovenia (locality also sometimes given as Gorizia, Italy). ...

'' Heckel, 1849 ** '' Chiromystus'' Cope, 1885 ** ''

Cladocyclus ''Cladocyclus'' (derived from the Ancient Greek, Greek κλάδος/kládos ("branch") and κύκλος/kýklos ("circle")) is an extinct genus of marine Ichthyodectiformes, ichthyodectiform ray-finned fish from the middle Cretaceous. It was a p ...

'' Agassiz, 1841 ** '' Cladocynodon'' de Mayrinck ''et al.'', 2023 ** '' Eubiodectes'' Hay, 1903 * Ichthyodectidae Crook, 1892 ** '' Cooyoo'' Bartholomai & Less, 1987 ** '' Ghrisichthys'' Cavin ''et al.'', 2013 ** ''

'' Cope, 1870 ** '' Postredectes'' Kaddumi, 2009 ** ''

Xiphactinus ''Xiphactinus'' (from Latin and Greek for "sword-ray") is an extinct genus of large predatory marine ray-finned fish that lived during the late Albian to the late Maastrichtian. The genus grew up to in length, and superficially resembled a garga ...

'' Leidy, 1870 * Heckelichthyidae Alvarado-Ortega, 2024 ** '' Altamuraichthys''? Taverne, 2016 ** '' Amakusaichthys'' Yabumoto ''et al.'', 2020 ** '' Garganoichthys''? Taverne, 2009 ** '' Heckelichthys'' Taverne, 2008 * Saurodontidae

Cope A cope ( ("rain coat") or ("cape")) is a liturgical long mantle or cloak, open at the front and fastened at the breast with a band or clasp. It may be of any liturgical colour. A cope may be worn by any rank of the Catholic or Anglican clerg ...

, 1870 Cope, E. D. (1870). On the Saurodontidæ. ''Proceedings of the American Philosophical Society'' 11:529-538 Cope, E. D. (1873). On two new species of Saurodontidae. ''Proceedings of the Academy of Natural Sciences of Philadelphia'' 25:2-339 ** '' Gillicus'' Cope, 1875 ** ''

Gwawinapterus ''Gwawinapterus beardi'' is a species of saurodontid ray-finned fish from the Late Cretaceous period of British Columbia, Canada. While initially described as a very late-surviving member of the pterosaur family Istiodactylidae, further examinat ...

'' Arbour & Currie, 2011Vullo, R., Buffetaut, E. and Everhart, M.J. (2012). "Reappraisal of ''Gwawinapterus beardi'' from the Late Cretaceous of Canada: a saurodontid fish, not a pterosaur." ''Journal of Vertebrate Paleontology'', 32(5): 1198-1201. ** '' Prosaurodon'' Stewart, 1999 ** ''

Saurocephalus ''Saurocephalus'' (from , 'lizard' and 'head') is an extinct genus of ray-finned fishes within the family Saurodontidae.Maisey, J. G.1991. ''Santana Fossils, an Illustrated Atlas''. New Jersey, T.F.H. Publications Inc., 190–207. The genus ...

'' Harlan, 1824 ** '' Saurodon'' Hay, 1830 ** '' Vallecillichthys'' Blanco & Cavin, 2003

References

External links

* * {{Taxonbar, from=Q1656407 Prehistoric teleostei Prehistoric ray-finned fish orders Late Jurassic first appearances Paleocene extinctions Taxa described in 1969