Pachycormiformes

{{Short description|Extinct order of ray-finned fishes}} {{Automatic taxobox | fossil_range = Early Jurassic - Late Cretaceous, {{fossilrange|Toarcian|Maastrichtian}} | image = Pachycormus bollensis - Naturmuseum Senckenberg - DSC02210 (cropped).JPG | image_caption = Skeleton of ''Pachycormus'' | image2 = Orthocormus cornutus 1.JPG | image2_caption = Skeleton of ''Orthocormus'' | display_parents = 3 | parent_authority = Berg 1937 | taxon = Pachycormidae | authority = Woodward, 1895 | type_genus = ''Pachycormus'' | type_genus_authority = Agassiz, 1833 | subdivision_ranks = Genera | subdivision = See text | synonyms_ref = <ref name="van der Laan2018">{{cite journal |last1=van der Laan |first1=R. |title=Family-group names of fossil fishes |journal=European Journal of Taxonomy |date=2018 |issue=466 |doi=10.5852/ejt.2018.466|doi-access=free }}</ref> | synonyms = * Diphyodontidae Jordan, 1923 * Erisichtheidae Cope, 1877b * Microlepidoti Zittel, 1887 * Pelecopteridae Cope, 1875 * Protosphyraenidae Lydekker, 1889 * Sauropsidae Cope, 1877a * Saurotomini [Saurostomini] Bonaparte, 1846 corrig. Bonaparte 1850a }}

'''Pachycormiformes''' is an extinct order of marine ray-finned fish known from the Early Jurassic to the end of the Cretaceous. Depending on the treatment, it only includes a single family, '''Pachycormidae''', or two families: the mostly filter-feeding Pachycormidae and the carnivorous '''Protosphyraenidae'''. They were characterized by having serrated pectoral fins (though more recent studies demonstrated that fin shape diversity in this group was high<ref>{{Cite journal|last1=Liston|first1=Jeff J.|last2=Maltese|first2=Anthony E.|last3=Lambers|first3=Paul H.|last4=Delsate|first4=Dominique|last5=Harcourt-Smith|first5=William E. H.|last6=Heteren|first6=Anneke H. van|date=2019-11-07|title=Scythes, sickles and other blades: defining the diversity of pectoral fin morphotypes in Pachycormiformes|journal=PeerJ|language=en|volume=7|article-number=e7675|doi=10.7717/peerj.7675|pmid=31720097|pmc=6842561|issn=2167-8359 |doi-access=free }}</ref>), reduced pelvic fins and a bony rostrum. Pachycormiformes are morphologically diverse, containing both tuna and swordfish-like carnivorous forms, as well as edentulous suspension-feeding forms.

== Description == left|thumb|Size comparison of various species of Pachycormiform fish Pachycormiformes are united by "a compound bone (rostrodermethmoid) forming the anterodorsal border of the mouth; a reduced coronoid process of the mandible; absence of supraorbitals associated with a dermosphenotic defining the dorsal margin of the orbit; two large, plate-like suborbital bones posterior to the infraorbitals; long, slender pectoral fins; asymmetrical branching of pectoral fin lepidotrichia; considerable overlap of the hypurals by caudal fin rays (hypurostegy); and the presence of distinctive uroneural-like ossifications of the caudal fin endoskeleton".<ref>{{Cite journal|last1=Dobson|first1=Claire|last2=Giles|first2=Sam|last3=Johanson|first3=Zerina|last4=Liston|first4=Jeff|last5=Friedman|first5=Matt|date=2019-09-03|title=Cranial osteology of the Middle Jurassic (Callovian) Martillichthys renwickae (Neopterygii, Pachycormiformes) with comments on the evolution and ecology of edentulous pachycormiforms|journal=Papers in Palaeontology|volume=7|pages=111–136|doi=10.1002/spp2.1276|hdl=2027.42/167090 |s2cid=202919395|issn=2056-2802|url=https://ora.ox.ac.uk/objects/uuid:e93fadf1-93da-4727-aad7-beeeacd09657|hdl-access=free}}</ref> Pachycormiformes varied substantially in size, from medium-sized fishes around {{Convert|40-111|cm|ft}} in length like the macropredator ''Pachycormus'',<ref>{{Cite journal |last1=Gouiric-Cavalli |first1=Soledad |last2=Cione |first2=Alberto Luis |date=2015-07-04 |title=Notodectes is the first endemic pachycormiform genus (Osteichthyes, Actinopterygii, Pachycormiformes) in the Southern Hemisphere |url=http://www.tandfonline.com/doi/full/10.1080/02724634.2014.933738 |journal=Journal of Vertebrate Paleontology |language=en |volume=35 |issue=4 |article-number=e933738 |doi=10.1080/02724634.2014.933738 |issn=0272-4634|hdl=11336/13733 |hdl-access=free }}</ref> to the largest known ray-finned fish, the suspension feeding ''Leedsichthys'', which is estimated to have reached a maximum length of around {{Convert|16|m|ft}}.<ref name="Liston2013">{{cite book |author=Liston, J., Newbrey, M., Challands, T., and Adams, C., 2013 |title=Mesozoic Fishes 5 – Global Diversity and Evolution |publisher=Verlag Dr. Friedrich Pfeil |isbn=978-3-89937-159-8 |editor=Arratia, G., Schultze, H. and Wilson, M. |location=München, Germany |pages=145–175 |chapter=Growth, age and size of the Jurassic pachycormid ''Leedsichthys problematicus'' (Osteichthyes: Actinopterygii) |date=2013 |chapter-url=https://eprints.gla.ac.uk/81797/1/81797.pdf}}</ref>

== Evolution ==

=== Relationships === Pachycormiformes are generally interpreted as basal members of Teleosteomorpha, the group that includes all fish more closely related to modern teleosts than to Holostei (the group containing bowfin and gars), often they have been considered to be the sister group of the Aspidorhynchiformes.<ref>{{Cite journal|last1=Peskin|first1=Brianna|last2=Henke|first2=Katrin|last3=Cumplido|first3=Nicolás|last4=Treaster|first4=Stephen|last5=Harris|first5=Matthew P.|last6=Bagnat|first6=Michel|last7=Arratia|first7=Gloria|date=2020-07-20|title=Notochordal Signals Establish Phylogenetic Identity of the Teleost Spine|journal=Current Biology|language=en|volume=30|issue=14|pages=2805–2814.e3|doi=10.1016/j.cub.2020.05.037|pmid=32559448| pmc=8159021 |issn=0960-9822}}</ref><ref>{{Cite journal |last=Arratia |first=Gloria |date=2017-03-04 |title=New Triassic teleosts (Actinopterygii, Teleosteomorpha) from northern Italy and their phylogenetic relationships among the most basal teleosts |url=https://www.tandfonline.com/doi/full/10.1080/02724634.2017.1312690 |journal=Journal of Vertebrate Paleontology |language=en |volume=37 |issue=2 |article-number=e1312690 |doi=10.1080/02724634.2017.1312690 |issn=0272-4634|url-access=subscription }}</ref>

=== Taxonomy === Most authors have long divided the Pachycormiformes into two groups, a filter-feeding clade and a macropredatory clade, but the circumscription of these groups has frequently shifted. Prior to 1895, short-snouted pachycormiforms were placed in the family Pachycormidae, while the unusual long-snouted ''Protosphyraena'' was placed in its own family, Protosphyraenidae. In 1895, ''Protosphyraena'' was also reclassified by Woodward as a pachycormid. Later studies affirmed the presence of a predatory and a filter-feeding lineage within the order.<ref name=":0" />

In 2022, the two lineages were described as distinct subfamilies: Hypsocorminae for the toothed clade, and Asthenocorminae for the filter-feeding clade. Despite having teeth, ''Pachycormus'' was found to be more closely related to the filter-feeding asthenocormines.<ref name="Cooper2022" /> In 2026, the well-preserved ''Hypsocormus guschchinae'' was described, with analysis of its pectoral fin morphology confirming the relationship of short-snouted predatory "hypsocormines" to ''Protosphyraena''. For this reason, the former family Protosphyraenidae was revived for the predatory pachycormiforms that belonged to the same lineage as ''Protosphyraena''.<ref name=":0" />

Taxonomy according to Kanarkina, Zverkov & Valenov (2026):<ref name=":0">{{Cite journal |last=Kanarkina |first=Alina |last2=Zverkov |first2=Nikolay G |last3=Varenov |first3=Dmitry V |date=2026-02-03 |title=A new species of the Late Jurassic pachycormiform fish Orthocormus and comments on the beta taxonomy and phylogenetic systematics of the Pachycormiformes |url=https://academic.oup.com/zoolinnean/article/doi/10.1093/zoolinnean/zlag009/8500384 |journal=Zoological Journal of the Linnean Society |language=en |volume=206 |issue=2 |doi=10.1093/zoolinnean/zlag009 |issn=0024-4082|url-access=subscription }}</ref><ref name="Cooper2022">{{cite journal |last1=Cooper |first1=S. L. A. |last2=Giles |first2=S. |last3=Young |first3=H. |last4=Maxwell |first4=E. E. |title=A New Large †Pachycormiform (Teleosteomorpha: †Pachycormiformes) from the Lower Jurassic of Germany, with Affinities to the Suspension-Feeding Clade, and Comments on the Gastrointestinal Anatomy of Pachycormid Fishes |journal=Diversity |date=2022 |volume=14 |issue=12 |page=1026 |doi=10.3390/d14121026|doi-access=free }}</ref>

* Order '''Pachycormiformes''' ** ?''Eugnathides'' Gregory, 1923 ** ''Haasichthys'' Delsate, 1999 ** ''Notodectes'' Dolgopol de Saez, 1949 ** Superfamily '''Pachycormoidea''' *** Family '''Pachycormidae''' Lyddeker, 1889 **** ''Germanostomus'' Cooper ''et al.'', 2022<ref name="Cooper2022" /> **** ''Saurostomus'' Agassiz, 1843 **** Subfamily '''Pachycorminae''' Lyddeker, 1889 ***** ''Pachycormus'' Agassiz, 1833 ****Subfamily '''Asthenocorminae''' Cooper ''et al.'', 2022 *****''Asthenocormus'' Woodward, 1895 ***** ''Bonnerichthys'' Friedman ''et al.'', 2010 ***** ''Leedsichthys'' Woodward, 1889 ***** ''Martillichthys'' Liston, 2008 ***** ''Ohmdenia'' Hauff, 1953 ***** ''Rhinconichthys'' Friedman ''et al.'', 2010 *** Family '''Protosphyraenidae''' Woodward, 1888 **** ''Euthynotus'' Wagner, 1860 (potentially a basal pachycormiform) **** ''Hypsocormus'' Wagner, 1860 **** ''Kaykay'' Gouiric-Cavalli & Arratia, 2022<ref>{{cite journal |last1=Gouiric-Cavalli |first1=S. |last2=Arratia |first2=G. |title=A new †Pachycormiformes (Actinopterygii) from the Upper Jurassic of Gondwana sheds light on the evolutionary history of the group |journal=Journal of Systematic Palaeontology |date=2022 |volume=19 |issue=21 |pages=1517–1550 |doi=10.1080/14772019.2022.2049382|s2cid=248454343 }}</ref> **** ''Pseudoasthenocormus'' Lambers, 1992 **** ''Sauropsis'' Agassiz, 1843 **** ''Simocormus'' Maxwell ''et al.'', 2020 **** Subfamily '''Protosphyraeninae''' Woodward, 1888 ***** ''Erisichthe'' Cope, 1872<ref name=":0" /> ***** ''Paraorthocormus'' Kanarkina, Zverkov & Valenov, 2026<ref name=":0" /> ***** ''Orthocormus'' Weitzel, 1930 ***** ''Protosphyraena'' Leidy, 1857

=== Phylogeny === Cladistics according to Friedman ''et al.'' (2010).<ref name="Friedman2">{{Cite journal|author1=Matt Friedman|author2=Kenshu Shimada|author3=Larry D. Martin|author4=Michael J. Everhart|author5=Jeff Liston|author6=Anthony Maltese|author7=Michael Triebold|year=2010|title=100-million-year dynasty of giant planktivorous bony fishes in the Mesozoic seas.|url=http://science-mag.aaas.org/cgi/content/abstract/327/5968/990|journal=Science|volume=327|issue=5968|pages=990–993|doi=10.1126/science.1184743|pmid=20167784|bibcode=2010Sci...327..990F |s2cid=206524637}}</ref>

{{clade |label1=Pachycormiformes |1={{clade |1=''†Euthynotus'' |2={{clade |1={{clade |1=''†Hypsocormus insignis'' |2={{clade |1=''†"Hypsocormus" tenuirostris'' |2={{clade |1=''†Orthocormus'' |2={{clade |1=''†Australopachycormus'' |2=''†Protosphyraena'' }} }} }} }} |2={{clade |1=''†Pachycormus'' |label2=Suspension feeding clade |2={{clade |1={{clade |1=''†Asthenocormus titanius'' |2=''†Martillichthys renwickae'' }} |2={{clade |1=''†Bonnerichthys gladius'' |2={{clade |1=''†Leedsichthys problematicus'' |2=''†Rhinconichthys taylori''

}} }} }} }} }} }} }}

== Gallery == {{gallery|Protosphyraena_perniciosa.png|Reconstruction of ''Protosphyraena perniciosa''|File:Leedsichthys paleoart.jpg|Speculative life restoration of ''Leedsichthys''|File:Ohmdenia Illustration.png|Life restoration of ''Ohmdenia''|File:Bonnerichthys gladius.png|Life restoration of ''Bonnerichthys''|width=180|height=180|File:Illustration of Pachycormus macropterus.jpg |Life restoration of ''Pachycormus''|Orthocormus cornutus.png|Life restoration of ''Orthocormus''}}

==References== {{Reflist}}

Category:Pachycormiformes Category:Late Triassic first appearances Category:Maastrichtian extinctions Category:Prehistoric ray-finned fish orders Category:Monotypic vertebrate orders