{{Short description|Extinct order of fishes}} {{Automatic taxobox | fossil_range = {{fossilrange|Late Triassic|Eocene}} | image = Pycnodont_diversity.png | image_caption = Pycnodontiform diversity | taxon = Pycnodontiformes | authority = Berg, 1937 | subdivision_ranks = Families | subdivision = * Brembodontidae * Coccodontidae * Gebrayelichthyidae * Gladiopycnodontidae * Gyrodontidae * Hadrodontidae * Mesturidae * Pycnodontidae }}
'''Pycnodontiformes''' is an extinct order of primarily marine bony fish. The group first appeared during the Late Triassic and disappeared during the Eocene. The group has been found in rock formations in Africa, Asia, Europe, North and South America.<ref name="Palaeos">{{cite web| url=http://www.palaeos.com/Vertebrates/Units/100Neopterygii/100.600.html#Pycnodontiformes| title=Pycnodontiformes| publisher=Palaeos vertebrates| access-date=27 July 2009| url-status=dead| archive-url=https://web.archive.org/web/20081025044133/http://www.palaeos.com/Vertebrates/Units/100Neopterygii/100.600.html#Pycnodontiformes| archive-date=25 October 2008}}</ref>
They were small to middle-sized fish, generally with laterally-compressed deep bodies, some with almost circular outlines,<ref name="Kansas">{{cite web| url=http://www.oceansofkansas.com/Pycnodont.html| title=Pycnodontid fishes from the Kansas Cretaceous| publisher=Oceans of Kansas| date=16 April 2009| access-date=29 July 2009}}</ref> adapted for manoeuvrability in reef-like environments, though the group was morphologically diverse.<ref name=":0" /> Most, but not all members of the groups had jaws with round and flattened teeth,<ref>{{Cite book |year = 2009 |title = Paleotorus: The Laws of Morphogenetic Evolution |publisher = Meanma Press |author1 = McMenamin, M. A. S. |isbn = 978-1-893882-18-8}}</ref> well adapted to crush food items (durophagy), such as echinoderms, crustaceans and molluscs.<ref name=":0">{{Cite journal |last1=Cawley |first1=John J. |last2=Marramà |first2=Giuseppe |last3=Carnevale |first3=Giorgio |last4=Villafaña |first4=Jaime A. |last5=López-Romero |first5=Faviel A. |last6=Kriwet |first6=Jürgen |date=February 2021 |title=Rise and fall of †Pycnodontiformes: Diversity, competition and extinction of a successful fish clade |journal=Ecology and Evolution |language=en |volume=11 |issue=4 |pages=1769–1796 |doi=10.1002/ece3.7168 |issn=2045-7758 |pmc=7882952 |pmid=33614003}}</ref> Some pycnodontiformes developed piranha like teeth used for eating flesh.<ref>{{Cite journal |last1=Kölbl-Ebert |first1=Martina |last2=Ebert |first2=Martin |last3=Bellwood |first3=David R. |last4=Schulbert |first4=Christian |date=2018-11-05 |title=A Piranha-like Pycnodontiform Fish from the Late Jurassic |journal=Current Biology |language=en |volume=28 |issue=21 |pages=3516–3521.e2 |doi=10.1016/j.cub.2018.09.013 |pmid=30344113 |s2cid=53045425 |issn=0960-9822|doi-access=free }}</ref><ref>{{Cite journal |last1=Vullo |first1=Romain |last2=Cavin |first2=Lionel |last3=Khalloufi |first3=Bouziane |last4=Amaghzaz |first4=Mbarek |last5=Bardet |first5=Nathalie |last6=Jalil |first6=Nour-Eddine |last7=Jourani |first7=Essaid |last8=Khaldoune |first8=Fatima |last9=Gheerbrant |first9=Emmanuel |date=2017-07-28 |title=A unique Cretaceous–Paleogene lineage of piranha-jawed pycnodont fishes |journal=Scientific Reports |language=en |volume=7 |issue=1 |pages=6802 |doi=10.1038/s41598-017-06792-x |pmid=28754956 |pmc=5533729 |issn=2045-2322}}</ref> Most species inhabited shallow marine reef environments, while a handful of species lived in freshwater or brackish conditions.
While rare during the Triassic and Early-Middle Jurassic, Pycnodontiformes became abundant and diverse during the Late Jurassic, exhibiting a high but relatively static diversity during the Early Cretaceous. At the beginning of the Late Cretaceous they reached their apex of morphological and species diversity (much of this due to fossils found in the Sannine Formation of Lebanon, such as Gebrayelichthyidae and ''Ichthyoceros''), after which they began to gradually decline, with a more sudden decline at the end of the Cretaceous due to the collapse of reef ecosystems, finally becoming extinct during the Eocene. They are considered to belong to the Neopterygii, but their relationship to other members of that group is uncertain.<ref name=":0" />
== Evolution and diversity == [[File:Eomesodon gibbosus 723.jpg|thumb|''Macromesodon gibbosus'' (formerly species of ''Eomesodon''), a species of Brembodontidae from the Jurassic Solnhofen Limestone.]] Pycnodontiforms first appeared in the Late Triassic, alongside other successful groups of early neopterygians such as dapediiforms. A contributor for this early radiation of neopterygians was their effectiveness at adapting to different diets. Pycnodonts from the Late Triassic Zorzino Limestone in Italy had short and stout jaws with big crushing teeth for eating hard-shelled prey, while other actinopterygians like saurichthyids and birgeriids mainly occupied top predator piscivorous niches. They originated from marine habitats, specializing for manoeuverability in reef environments, but developed a variety of adaptations during the Mesozoic that enable them to pursue new diets and habitats, such as estuaries and freshwaters. Only a few species adapted for open waters, like those of the family Gyrodontidae.<ref name=":0" /> In the Western Tethys, pycnodonts have always had a high species diversity. This stable environment, alongside its favorable climate conditions, supported the dispersal patterns within basal pycnodontids.<ref name=":2" />
They evolved such different jaw structures to avoid potential competition with other groups of durophagous neopterygians, such as the Dapediiformes and the Ginglymodi. Furthermore, their improved jaw performance also differentiated the pycnodonts from these neopterygians in that they allowed them to feed on tougher prey, while their increase in size allowed them to prey on larger items or specialise on a few species. Their families also differentiated amongst themselves in body and jaw shape, implying that they were more diverse in diet and habitat than previously thought.<ref name=":0" />
The fossil record of pycnodonts spans 175 million years, from the Triassic to the Eocene, existing longer than non-avian dinosaurs. Their early record is incomplete, having only three genera from the Late Triassic, all with complete specimens. Whereas from the Early to Mid-Jurassic there are only isolated teeth and jaws, and rarely a few exceptions for better, but still incomplete, fossils. By the Late Jurassic Pycnodontiforms became more common in the fossil record, a fact that relates to the presence of Lagerstätten, providing articulated fossils. This growth continues and, by the Late Cretaceous, they experience a peak in diversity during the Cenomanian. They were severely struck by the K/Pg Extinction and afterwards their diversity shrunk, having never achieved pre-extinction levels of diversity, eventually going extinct by the Late Eocene (Priabonian).<ref name=":0" />
==Taxonomy==
* '''Order Pycnodontiformes (Berg, 1937)'''<ref name="Nelson">{{cite book|last1=Nelson|first1=Joseph S.|last2=Grande|first2=Terry C.|last3=Wilson|first3=Mark V. H.|year=2016|title=''Fishes of the World''|edition=5th|publisher=John Wiley & Sons|isbn=9781118342336}}</ref><ref name="van der Laan">{{cite journal|last=van der Laan|first=Richard|year=2016|title=''Family-group names of fossil fishes''|url=https://www.researchgate.net/publication/303911230}}</ref> ** Genus ?''Acrorhinichthys'' <small>Taverne & Capasso, 2015</small> ** Genus ?''Archaeopycnodon'' <small>Sanchez & Benedetto, 1980</small> ** Genus ''Arduafrons'' <small>Frickhinger, 1991</small> ** Genus ?''Athrodon'' <small>le Sauvage 1880 non Osborn, 1887</small> ** Genus ?''Callodus'' <small>Thurmond, 1974</small> ** Genus ?''Ellipsodus'' <small>Cornuel, 1877</small> ** Genus ?''Grypodon'' <small>Hay, 1899</small> [''Ancistrodon'' <small>Dames, 1883 non De Beauvois, 1799 non Roemer, 1852 non Wagler, 1830</small>] ** Genus ?''Mercediella'' <small>Koerber, 2012</small> [''Camposichthys'' <small>Figueiredo & Silva-Santos, 1991 non Travassos, 1946 non Whitley, 1953</small>] **Genus ''Paramesturus'' <small>Taverne, 1981</small> **Genus ?''Piranhamesodon'' <small>Kölbl-Ebert ''et al.'', 2018</small> ** Genus ?''Pseudopycnodus'' <small>Taverne, 2003</small> ** Genus ?''Tergestinia'' <small>Capasso, 2000</small> ** Genus ?''Thurmondella'' <small>Thurmond, 1974 non</small> [''Paramicrodon'' <small>Thurmond, 1974 non de Meijere, 1913</small>] ** Genus ?''Uranoplosus'' <small>le Sauvage, 1879</small> ** Genus ?''Woodthropea'' <small>Swinnerton, 1925</small> **'''Family''' '''Brembodontidae''' <small>Tintori, 1981</small> [Brembodidae; Gibbodontidae <small>Tintori, 1981</small>]<ref name=":3">{{Cite journal |last=Ebert|first=Martin|date=2026-02-03|title=Macromesodon Blake, 1905 and Apomesodon Poyato-Ariza & Wenz, 2002 (Actinopterygii, Pycnodontiformes) from the Jurassic and lowermost Cretaceous of England, France, and Germany|url=https://sjp.pensoft.net/article/177263/|journal=Swiss Journal of Palaeontology|language=en|volume=145|pages=97–129|doi=10.3897/sjp.145.177263|issn=1664-2384|doi-access=free}}</ref> *** Genus ''Brembodus'' <small>Tintori, 1981</small> *** Genus ''Eomesodon'' <small>Woodward, 1918</small> *** Genus ''Gibbodon'' <small>Tintori, 1981</small> **'''Family''' ?'''Hadrodontidae''' <small>Thurmond & Jones, 1981</small> *** Genus ''Hadrodus'' <small>Leidy, 1858</small> [''Propenser'' <small>Applegate, 1970</small>] **'''Family''' '''Gyrodontidae''' <small>Berg, 1940</small> *** Genus ''Gyrodus'' <small>Agassiz, 1833</small> **'''Family Macromesodontidae''' ***Genus ''Macromesodon'' <small>Blake 1905 non Lehman, 1966</small> [''Mesodon'' <small>Wagner, 1851 non Rafinesque, 1821</small>; ''Gyronchus'' <small>Agassiz, 1839</small>; ''Apomesodon'' <small>Poyato-Ariza & Wenz, 2002</small>]<ref name=":3" /> **'''Family''' '''Mesturidae''' <small>Nursall, 1996</small> *** Genus ''Mesturus'' <small>Wagner, 1862</small> **'''Family''' '''Pycnodontidae''' <small>Agassiz, 1833 corrig. Bonaparte, 1845</small> [Nursalliidae <small>Bloy, 1987</small>; Sphaerodontidae <small>Giebel, 1846</small>; Palaeobalistidae <small>Blot, 1987</small>; Proscinetidae <small>Gistel, 1848</small>; Gyronchidae]thumb|Fossil of ''Neoproscinetes penalvai'' *** Genus ''Abdobalistum'' <small>Poyato-Ariza & Wenz, 2002</small> *** Genus ''Acrotemnus'' <small>Agassiz, 1843</small> (=''Macropycnodon'' <small>Shimada, Williamson & Sealey, 2010</small>) *** Genus ?''Agassizilia'' <small>Cooper & Martill, 2020</small><ref>{{Cite journal |last1=Cooper |first1=Samuel L. A. |last2=Martill |first2=David M. |date=2020-08-01 |title=A diverse assemblage of pycnodont fishes (Actinopterygii, Pycnodontiformes) from the mid-Cretaceous, continental Kem Kem Group of south-east Morocco |url=https://www.sciencedirect.com/science/article/pii/S0195667120300136 |journal=Cretaceous Research |volume=112 |article-number=104456 |bibcode=2020CrRes.11204456C |doi=10.1016/j.cretres.2020.104456 |issn=0195-6671|url-access=subscription }}</ref> *** Genus ''Agoultpycnodus'' <small>Taverne & Capasso, 2021</small> *** Genus ''Akromystax'' <small>Poyato-Ariza & Wenz, 2005</small> *** Genus ''Anomiophthalmus'' <small>Costa, 1856</small> *** Genus ''Anomoeodus'' <small>Forir, 1887</small> *** Genus ''Apomesodon'' <small>Poyato-Ariza & Wenz, 2002</small> *** Genus ''Athrodon'' <small>Sauvage, 1880</small> *** Genus ''Brauccipycnodus'' <small>Taverne & Capasso, 2021</small> *** Genus ''Coelodus'' <small>Heckel, 1854</small> *** Genus ''Costapycnodus'' <small>Taverne, Capasso & del Re, 2019</small> *** Genus ''Flagellipinna'' <small>Cawley & Kriwet, 2019</small> *** Genus ''Gregoriopycnodus'' <small>Taverne, Capasso & del Re, 2020</small> *** Genus ''Haqelpycnodus'' <small>Taverne & Capasso, 2018</small> *** Genus ''Iemanja'' <small>Wenz, 1989</small> *** Genus ''Libanopycnodus'' <small>Taverne & Capasso, 2018</small> *** Genus ''Micropycnodon'' <small>Hibbard & Graffham, 1945</small> *** Genus ?''Neomesturus'' <small>Cooper & Martill 2020</small><ref>Cooper, S.L.A. and Martill, D.M. (2020). "Pycnodont fishes (Actinopterygii: Pycnodontiformes) from the Upper Cretaceous (lower Turonian) Akrabou Formation of Asfla, Morocco" Cretaceous Research 116, 104607</ref> *** Genus ''Neoproscinetes'' <small>De Figueiredo & Silva Santos, 1990</small> *** Genus ''Njoerdichthys'' <small>Cawley, Lehmann, Wiese & Kriwet, 2020</small><ref name=":2">{{Cite journal |last1=Cawley |first1=John |last2=Lehnmann |first2=Jens |last3=Wiese |first3=Frank |last4=Kriwet |first4=Jürgen |date=2020 |title=Njoerdichthys dyckerhoffi gen. et sp. nov. (Pycnodontiformes, lower Turonian) northward migration caused by the Cretaceous Thermal Maximum |url=https://www.sciencedirect.com/science/article/pii/S0195667120302767#fig3 |journal=Cretaceous Research |volume=116}}</ref> *** Genus ''Nonaphalagodus'' <small>Thurmond, 1974</small> *** Genus ''Nursallia'' <small>Blot, 1987</small> *** Genus ''Ocloedus'' <small>Poyato-Ariza & Wenz, 2002</small> *** Genus ''Omphalodus'' <small>von Meyer, 1847</small> *** Genus ''Oropycnodus'' <small>Poyato-Ariza & Wenz, 2002</small> *** Genus ''Palaeobalistum'' <small>Taverne ''et al.'', 2015</small> *** Genus ''Paranursallia'' <small>Taverne ''et al.'', 2015</small> *** ?Genus ''Phacodus'' <small>Dixon, 1850</small> *** Genus ''Polazzodus'' <small>Poyoto-Ariza, 2010</small> *** Genus ''Polypsephis'' <small>Hay, 1899 (</small>=''Microdon'' <small>Agassiz 1833</small> (preoccupied)) *** Genus ''Potiguara'' <small>Machado & Brito, 2006</small> *** Genus ''Proscinetes'' <small>Gistl, 1848</small> [''Microdon'' <small>Agassiz, 1833 non Meigen, 1803 non Fritsch, 1876 non Conrad, 1842 non Gistl, 1848 non Dixon, 1850</small>; ''Polypsephis'' <small>Hay, 1899</small>] *** Genus ''Pycnodus'' <small>Agassiz, 1833</small> *** Genus ''Pycnomicrodon'' <small>Hay 1916 non Hibbard & Graffham, 1941</small> *** Genus ''Rhinopycnodus'' <small>Taverne & Capasso, 2013</small> *** Genus ''Scalacurvichthys'' <small>Cawley & Kriwet, 2017</small> *** Genus ''Sigmapycnodus'' <small>Taverne & Capasso, 2018</small> *** Genus ''Sphaerodus'' <small>Agassiz, 1833</small> *** Genus ''Sphaeronchus'' <small>Stinton & Torrens, 1967</small> *** Genus ''Stenamara'' <small>Poyato-Ariza & Wenz, 2000</small> *** Genus ''Stemmatias'' <small>Hay, 1899</small> [''Stemmatodus'' <small>St. John & Worthen, 1875 non Heckel, 1854 non</small>] *** Genus ''Stemmatodus'' <small>Heckel, 1854 non St. John & Worthen, 1875 non</small> *** Genus ''Sylvienodus'' <small>Poyato-Ariza & Wenz, 2013</small>thumb|Life Reconstruction of ''Thiollierepycnodus wagneri'' *** Genus ''Tepexichthys'' <small>Applegate, 1992</small> *** Genus ''Tergestinia'' <small>Capasso, 2000</small> *** Genus ''Texasensis'' <small>Özdikmen, 2009</small> (=''Callodus'' <small>Thurmond, 1974</small> (preoccupied))<ref>{{Cite journal |last=Özdikmen |first=H. |date=2009-01-06 |title=Texasensis nom. nov., a new name for the preoccupied fossil fish genus Callodus Thurmond, 1974 (Osteichthyes: Pycnodontiformes) |url=https://www.munisentzool.org/Issue/abstract/texasensis-nom-nov-a-new-name-for-the-preoccupied-fossil-fish-genus-callodus-thurmond-1974-osteichthyes-pycnodontiformes_223 |journal=Texasensis Nom. Nov., A New Name for the Preoccupied Fossil Fish Genus Callodus Thurmond, 1974 (Osteichthyes: Pycnodontiformes) |language=en |volume=4 |issue=2 |pages=616 |issn=1306-3022}}</ref> *** Genus ''Thiollierepycnodus'' <small>Ebert, 2020</small> *** Genus ''Tibetodus'' <small>Young & Liu, 1954</small> *** Genus ''Turbomesodon'' <small>Poyato-Ariza & Wenz, 2004</small> [''Macromesodon'' <small>Lehman, 1966 non Blake, 1905</small>] *** Genus ''Typodus'' <small>Quenstedt, 1858</small> **'''Family Serrasalmimidae''' <small>Vullo ''et al'', 2017</small><ref>{{Cite journal |last1=Vullo |first1=Romain |last2=Cavin |first2=Lionel |last3=Khalloufi |first3=Bouziane |last4=Amaghzaz |first4=Mbarek |last5=Bardet |first5=Nathalie |last6=Jalil |first6=Nour-Eddine |last7=Jourani |first7=Essaid |last8=Khaldoune |first8=Fatima |last9=Gheerbrant |first9=Emmanuel |date=2017-07-28 |title=A unique Cretaceous-Paleogene lineage of piranha-jawed pycnodont fishes |journal=Scientific Reports |volume=7 |issue=1 |pages=6802 |doi=10.1038/s41598-017-06792-x |issn=2045-2322 |pmc=5533729 |pmid=28754956}}</ref> ***Genus ''Eoserrasalmimus'' <small>Vullo ''et al'', 2017</small> ***Genus ''Damergouia'' <small>Vullo ''et al'', 2017</small> ***Genus ''Polygyrodus'' <small>White, 1927</small> ***Genus ''Serrasalmimus'' <small>Vullo ''et al'', 2017</small> **'''Superfamily Coccodontoidea''' <small>Taverne & Capasso, 2013</small> ***Genus ''Congopycnodus'' <small>Taverne, 2019</small> ***'''Family''' '''Stanhopellidae''' <small>Capasso, 2023</small> **** Genus ''Stanhopella'' <small>Capasso, 2023</small> ***'''Family''' '''Coccodontidae''' <small>Berg, 1940</small> **** Genus ''Coccodus'' <small>Pictet, 1850</small> **** Genus ''Corusichthys'' <small>Taverne & Capasso, 2014</small> **** Genus ?''Cosmodus'' <small>le Sauvage, 1879</small> [''Glossodus'' <small>Costa, 1851 non Agassiz, 1828 ex Spix & Agassiz, 1829 non McCoy, 1848</small>] **** Genus ''Hensodon'' <small>Kriwet, 2004</small> **** Genus ''Ichthyoceros'' <small>Gayet, 1984</small> <ref name="TaverneCapassoCoccodontidae">{{cite journal |author1=L. Taverne |author2=L. Capasso |year=2014 |title=Ostéologie et phylogénie des Coccodontidae, une famille remarquable de poissons Pycnodontiformes du Crétacé supérieur marin du Liban, avec la description de deux nouveaux genres |url=http://www.palaeontos.be/25/det25.htm |url-status=dead |journal=Palaeontos |volume=25 |archive-url=https://web.archive.org/web/20170705013931/http://www.palaeontos.be/25/det25.htm |archive-date=2017-07-05 |access-date=2016-07-05}}</ref> **** Genus ''Paracoccodus'' <small>Taverne & Capasso, 2014</small> **** Genus ''Trewavasia'' <small>White & Moy-Thomas, 1941</small> [''Xenopholis'' <small>Davis, 1887 non Peters, 1869</small>; ''Xenopholoides'' <small>Fowler, 1958</small>] <ref name="TaverneCapassoCoccodontidae" /> ***'''Family''' '''Gebrayelichthyidae''' <small>Nursall & Capasso, 2004</small> **** Genus ''Gebrayelichthys'' <small>Nursall & Capasso, 2004</small> **** Genus ''Maraldichthys'' <small>Taverne & Capasso, 2014</small> ***'''Family''' '''Gladiopycnodontidae''' <small>Taverne & Capasso, 2013</small><ref>{{Cite journal |last1=Taverne |first1=Louis |last2=Capasso |first2=Luigi |date=2013-10-02 |title=Gladiopycnodontidae, a new family of pycnodontiform fishes from the Late Cretaceous of Lebanon, with the description of three genera |url=https://europeanjournaloftaxonomy.eu/index.php/ejt/article/view/178 |journal=European Journal of Taxonomy |language=en |issue=57 |doi=10.5852/ejt.2013.57 |issn=2118-9773|doi-access=free }}</ref> **** Genus ''Ducrotayichthys'' <small>Taverne & Capasso, 2015</small> **** Genus ''Gladiopycnodus'' <small>Taverne & Capasso, 2013</small> **** Genus ''Hayolperichthys'' <small>Taverne & Capasso, 2015</small> **** Genus ''Joinvillichthys'' <small>Taverne & Capasso, 2014</small> **** Genus ''Monocerichthys'' <small>Taverne & Capasso, 2013</small> **** Genus ''Pankowskichthys'' <small>Taverne & Capasso, 2014</small> **** Genus ''Rostropycnodus'' <small>Taverne & Capasso, 2013</small> **** Genus ''Stenoprotome'' <small>Hay, 1903</small> **** Genus ''Tricerichthys'' <small>Taverne & Capasso, 2015</small>
== Phylogeny == The phylogenetic relation between pycnodonts and other actinopterygians is uncertain. The difficulty of placing them on a phylogenetic tree arises from the fact that they are a clade defined by a high number of autapomorphies (characteristics shared by a single taxon), which makes them easy to identify, but also makes the study of their relations with other actinopterygians difficult, since characteristics shared by other groups might be obfuscated by the immense amount of features and diversity of pycnodonts.<ref name=":1" />
Previously, Pycnodontiformes where proposed to be a sister group of Teleostei or Teleosteomorpha, but in a 2015 analysis by Poyato-Ariza, they turned up as the most basal Neopterygii among the others of the group included, those being Lepisosteiformes, Semionotiformes, Macrosemiiformes, Halecomorphi and Teleostei.<ref name=":1">{{Cite journal |last=Poyato-Ariza |first=Francisco |date=2015 |title=Studies on Pycnodontid fishes (I): Evaluation of their phylogenetic position among actinopterygians |journal=Rivista Italiana di Paleontologia e Stratigrafia |volume=121 |issue=3 |pages=329–343}}</ref>
{{clade |label1=Actinopterygii |1={{clade |1={{clade |label1=Cladistia |1=''Polypterus'' }} |2={{clade |1={{clade |label1=Chondrostei |1=''Acipenser'' }} |label2=Neopterygii |2={{clade |1=†'''Pycnodontiformes''' |label2=Halecosmoti |2={{clade |label1=Holostei |1={{clade |label1=Halecomorpha |1={{clade |1=†''Caturus'' |2=†''Ionoscopus'' |3={{Clade |1=''Amia'' |2=†''Calamopleurus'' }} }} |label2=Ginglymodi |2={{clade |label1=†Macrosemiiformes |1=†Macrosemius |label2=Lepisosteiformes |2={{clade |label1=†Semionotiformes |1=†''Semionotus'' |2={{clade |1={{clade |1=†''Obaichthys'' |2=†''Dentilepisosteus'' }} |2={{clade |1=†''Masillosteus'' |2={{clade |1=†''Cuneatus'' |2={{clade |1=''Lepisosteus'' |2=''Atractosteus'' }} }} }} }} }} }} }} |label2=Teleosteomorpha |2={{clade |1=''Arapaima'' |2={{Clade |1=†''Pholidophorus'' |2=''Elops'' }} }} }} }} }} }} }}
As a means to avoid potential competition, the families of Pycnodontiforms evolved different body and jaw shapes, resulting in a highly diverse group.<ref name=":0" /> Pycnodontidae were the most advanced group, being the largest family, comprising 26 known described genera.<ref>{{Cite journal |last=Ebert |first=Martin |date=2020 |title=A new genus of Pycnodontidae (Actinopterygii) from the Upper Jurassic of France and Germany, included in a phylogeny of Pycnodontiformes |url=https://academic.oup.com/zoolinnean/article/188/2/434/5601911?login=false#198931046 |journal=Zoological Journal of the Linnean Society |volume=188 |issue=2 |pages=434–454}}</ref>
{{clade |label1='''Pycnodontiformes''' |1={{clade |1={{clade |1=''Paramesturus'' }} |2={{clade |1=''Palaeobalistum'' |2={{clade |label1=Mesturidae |1={{clade |1=''Micropycnodon'' |2=''Mesturus'' }} |2={{clade |label1=Gyrodontidae |1=''Gyrodus'' |2={{Clade |1=''Arduafrons'' |2={{Clade |1=''Piranhamesodon'' |2=''Apomesodon'' |3={{Clade |label1=Brembodontidae |1={{clade |1=''Brembodus'' |2={{clade |1=''Eomesodon'' |2=''Gibbodon'' }} }} |2={{clade |1=''Macromesodon'' |label2=Pycnodontidae |2={{clade |1=''Stenamara'' |2={{clade |label1=Proscinetinae |1={{clade |1=''Turbomesodon'' |2={{clade |1=''Turboscinetes'' |2={{Clade |1=''Thiollierepycnodus'' |2={{clade |1=''Neoproscinetes'' |2=''Proscinetes'' }} }} }} }} |2={{clade |1=''Stemmatodus'' |2={{clade |1={{clade |1={{clade |1=''Acromystax'' |2=''Ocloedus'' }} }} |2={{clade |1=''Lemanja'' |2={{clade |1=''Tepexichthys'' |2={{clade |1=''Scalacurvichthys'' |2={{clade |1=''Polazzodus'' |2=''Sylvienodus'' |3=''Coelodus'' |4=''Oropycnodus'' |5=''Pycnodus'' |label6=Nursalliinae |6={{clade |1={{clade |1=''Paranursallia'' |2=''Nursallia'' }} |2=''Abdobalistum'' }} }} }} }} }} }} }} }} }} }} }} }} }} }} }} }} }} }}
==References== {{Reflist}} {{Commons category|Pycnodontiformes}} {{Wikispecies|Pycnodontiformes}} * Capasso, Luigi (2021). "Pycnodonts: An overview and new insights in the Pycnodontomorpha Nursall, 2010". Occasional Paper of the University Museum of Chieti, Monographic Publication, 1: 1–223. Capasso, Luigi (2023). "Atlas of Pycnodonts: A pictorial guide to the Pycnodontomorpha (Pisces, Actinopterygii)". èDicola Publisher, Castellana, Italy; pp. 1-240. * {{cite journal | last = Sepkoski | first = Jack | title = A compendium of fossil marine animal genera | journal = Bulletins of American Paleontology | volume = 364 |page=560 | year = 2002 | url = http://strata.ummp.lsa.umich.edu/jack/showgenera.php?taxon=611&rank=class | access-date = 2011-05-17 }}
{{Evolution of fish|state=collapsed}} {{Pycnodontiformes}} {{Taxonbar|from=Q1787823}}
Category:Pycnodontiformes Category:Prehistoric ray-finned fish orders