Redfieldiiformes

{{Short description|Extinct order of ray-finned fishes}} {{Automatic taxobox | fossil_range = {{Fossil range|Induan|Sinemurian}} | image = Dictyopyge macrura (13206190804).jpg | image_caption = ''[[Dictyopyge|Dictyopyge macrurus]]'' from the [[Late Triassic]] of [[Virginia]] | taxon = Redfieldiiformes | authority = [[Lev Berg|Berg]], 1940 | type_genus = {{extinct}}''[[Redfieldius]]'' | type_genus_authority = [[Oliver Perry Hay|Hay]], 1899 | subdivision_ranks = Families | subdivision = *[[Brookvaliidae]] *[[Redfieldiidae]] }}

'''Redfieldiiformes''' is an [[extinct]] [[Order (biology)|order]] of [[ray-finned fish]] (actinopterygians) which lived from the [[Early Triassic]] to [[Early Jurassic]]. Redfieldiiforms were fairly typical Triassic fish in overall anatomy. They had a [[fusiform]] (streamlined, [[tuna]]-like) body shape with thick, [[ganoine]]-covered scales. The [[Dorsal fin|dorsal]] and [[Anal fin|anal]] fins were large, positioned opposite from each other, and shifted back, close to the tail. The [[caudal fin]] was hemiheterocercal, with the vertebral column and body scales extending into an upper lobe equal in size and shape to the lower lobe. They also had several characteristic skeletal traits, such as a hatchet-shaped [[preopercle]], a series of fulcra (thin spiny scales) fringing the fins, a reduced number of [[branchiostegal rays]] (typically just one), and a snout ornamented with tubercles.<ref name=":1">{{Cite journal|last1=Gouiric-Cavalli|first1=Soledad|last2=Zavattieri|first2=Ana M.|last3=Gutierrez|first3=Pedro R.|last4=Cariglino|first4=Bárbara|last5=Balarino|first5=Lucía|date=2017|title=Increasing the fish diversity of the Triassic faunas of Gondwana: a new redfieldiiform (Actinopterygii) from the Middle Triassic of Argentina and its palaeobiogeographical implications|url=https://onlinelibrary.wiley.com/doi/abs/10.1002/spp2.1089|journal=Papers in Palaeontology|language=en|volume=3|issue=4|pages=559–581|doi=10.1002/spp2.1089|s2cid=134580710 |issn=2056-2802|hdl=11336/57303|hdl-access=free}}</ref><ref name=":2">{{Cite journal|last=Gibson|first=Sarah Z.|date=2018-09-03|title=A new species of ''Lasalichthys'' (Actinopterygii, Redfieldiiformes) from the Upper Triassic Dockum Group of Howard County, Texas, with revisions to the genera ''Lasalichthys'' and ''Synorichthys''|url=https://par.nsf.gov/servlets/purl/10082031|journal=Journal of Vertebrate Paleontology|volume=38|issue=5|article-number=e1513009|doi=10.1080/02724634.2018.1513009|bibcode=2018JVPal..38E3009G |s2cid=92328870 |issn=0272-4634}}</ref><ref name=":0">{{Cite journal|last1=Kim|first1=Su-Hwan|last2=Lee|first2=Yuong-Nam|last3=Park|first3=Jin-Young|last4=Lee|first4=Sungjin|last5=Lee|first5=Hang-Jae|date=2020-04-01|title=The first record of redfieldiiform fish (Actinopterygii) from the Upper Triassic of Korea: Implications for paleobiology and paleobiogeography of Redfieldiiformes|url=https://www.sciencedirect.com/science/article/pii/S1342937X19303211|journal=Gondwana Research|language=en|volume=80|pages=275–284|doi=10.1016/j.gr.2019.11.008|bibcode=2020GondR..80..275K |s2cid=213571269 |issn=1342-937X|url-access=subscription}}</ref>

The [[maxilla]] has small teeth and is strongly connected to the preopercle; this would have allowed a deep gape to assist in [[ram feeding]].<ref name=":1" /> The function of the snout tubercles is uncertain; some authors have suggested that they attached to a fleshy upper lip,<ref name=":2" /> while others argue that they could have held sensory organs akin to the tubercles of siluriforms ([[catfish]]).<ref name=":0" />

Redfieldiiforms were fairly primitive 'subholostean' fish (more primitive than [[Holostei|holosteans]] such as [[gar]]s or the [[bowfin]]), with uncertain relations to [[Neopterygii|neopterygians]].<ref name=":1" /> Some studies draw comparisons to '[[Perleidiformes|perleidiforms]]' or [[Ptycholepiformes|ptycholepids]], while others consider redfieldiiforms to be early neopterygians related to [[Pholidopleuriformes|pholidopleuriforms]].<ref>{{Cite journal|last=Xu|first=Guang-Hui|date=2021|title=A new stem-neopterygian fish from the Middle Triassic (Anisian) of Yunnan, China, with a reassessment of the relationships of early neopterygian clades|url=https://www.researchgate.net/publication/342509835|journal=Zoological Journal of the Linnean Society|volume=191|issue=2|pages=375–394|doi=10.1093/zoolinnean/zlaa053|doi-access=free}}</ref> Redfieldiiforms were exclusively freshwater fish which became prominent in southern [[Gondwana]] ([[Argentina]], [[Australia]], southern [[Africa]]) during the Middle Triassic.<ref name=":0" /> By the [[Late Triassic]] they had become a major component of freshwater ecosystems in western [[Laurasia]] ([[North America]] and [[Morocco]]). However, they were much rarer further east ([[South Korea]],<ref name=":0" /> possibly [[Switzerland]]<ref name=":3">{{Cite journal |last=Lombardo |first=Cristina |date=2013 |title=A new basal actinopterygian fish from the Late Ladinian of Monte San Giorgio (Canton Ticino, Switzerland) |url=https://sjg.springeropen.com/articles/10.1007/s00015-013-0125-9 |journal=[[Swiss Journal of Geosciences]] |language=en |volume=106 |issue=2 |pages=219–230 |doi=10.1007/s00015-013-0125-9 |issn=1661-8734 |s2cid=129121812 |doi-access=free}}</ref>). The last member of the order, ''[[Redfieldius]]'', lived in the Early Jurassic of eastern North America.<ref name=":1" /><ref name=":0" />

== Taxonomy == The following families and genera are known:

* Order '''Redfieldiiformes''' ** Genus ''[[Calaichthys]]''<ref name=":1" /> ** Genus ''[[Denwoodichthys]]?'' ** Genus ''[[Helichthys]]'' ** Genus ''[[Hiascoactinus]]''<ref name=":0" /> ** ''Genus [[Pacorichthys]]?''<ref name=":3" /> ** Genus ''[[Sakamenichthys]]?'' ** Genus ''[[Sinkiangichthys]] ([[nomen dubium]])?'' ** Family [[Brookvaliidae]] *** Genus ''[[Atopocephala]]'' *** Genus ''[[Brookvalia]]'' *** Genus ''[[Ischnolepis (fish)|Ischnolepis]]'' *** Genus ''[[Phlyctaenichthys]]'' *** Genus ''[[Schizurichthys]]'' (formerly placed in the family Schizurichthyidae) **Family [[Redfieldiidae]] *** Genus ''[[Cionichthys]]'' *** Genus ''[[Endemichthys]]?'' *** Genus ''[[Daedalichthys]]'' *** Genus ''[[Dictyopyge]]'' *** Genus ''[[Geitonichthys]]'' *** Genus ''[[Lasalichthys]]'' (=''Synorichthys'')<ref>{{Cite journal |last=Gibson |first=Sarah Z. |date=2018-09-03 |title=A new species of Lasalichthys (Actinopterygii, Redfieldiiformes) from the Upper Triassic Dockum Group of Howard County, Texas, with revisions to the genera Lasalichthys and Synorichthys |url=https://www.tandfonline.com/doi/full/10.1080/02724634.2018.1513009 |journal=Journal of Vertebrate Paleontology |language=en |volume=38 |issue=5 |article-number=e1513009 |doi=10.1080/02724634.2018.1513009 |issn=0272-4634|url-access=subscription }}</ref> *** Genus ''[[Mauritanichthys]]'' *** Genus ''[[Molybdichthys]]'' *** Genus ''[[Redfieldius]]'' == References == {{Reflist}}

{{Neopterygii}} {{Taxonbar|from=Q19839167}} {{Authority control}}

[[Category:Redfieldiiformes| ]] [[Category:Prehistoric ray-finned fish orders]]

{{Paleo-rayfinned-fish-stub}} {{Triassic-fish-stub}} [[Category:Induan first appearances]] [[Category:Sinemurian extinctions]]