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. They were small to middle-sized fish, generally with laterally-compressed deep bodies, some with almost circular outlines, adapted for manuverability in reef-like environments. The group was morphologically diverse containing forms such the very short but deep Gebrayelichthyidae and the horned '' Ichthyoceros,'' both from the early Late Cretaceous of Lebanon. Most, but not all members of the groups had jaws with round and flattened teeth, well adapted to crush food items ( durophagy), such as echinoderms, crustaceans and molluscs. Some pyncodontiformes developed piranha like teeth used for eating flesh. 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, remaining diverse until a burst of diversification at the beginning of the Late Cretaceous, 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.

Taxonomy

* Order Pycnodontiformes (Berg, 1937) ** Genus ?'' Acrorhinichthys'' Taverne & Capasso, 2015 ** Genus ?'' Archaeopycnodon'' Sanchez & Benedetto, 1980 ** Genus ?'' Athrodon'' le Sauvage 1880 non Osborn, 1887 ** Genus ?''

Callodus ''Callodus'' is a monotypic genus of weevil Weevils are beetles belonging to the Taxonomic rank, superfamily Curculionoidea, known for their elongated snouts. They are usually small, less than in length, and Herbivore, herbivorous. Approxima ...

'' Thurmond, 1974 ** Genus ?'' Cosmodus'' le Sauvage, 1879 'Glossodus'' Costa, 1851 non Agassiz, 1828 ex Spix & Agassiz, 1829 non McCoy, 1848">Glossodus.html" ;"title="'Glossodus">'Glossodus'' Costa, 1851 non Agassiz, 1828 ex Spix & Agassiz, 1829 non McCoy, 1848** Genus ?''Ellipsodus'' Cornuel, 1877 ** Genus ?''Grypodon'' Hay, 1899 [''Ancistrodon'' Dames, 1883 non De Beauvois, 1799 non Roemer, 1852 non Wagler, 1830] ** Genus ?''[ ercediella'' Koerber, 2012 'Camposichthys'' Figueiredo & Silva-Santos, 1991 non Travassos, 1946 non Whitley, 1953">Camposichthys.html" ;"title="'Camposichthys">'Camposichthys'' Figueiredo & Silva-Santos, 1991 non Travassos, 1946 non Whitley, 1953**Genus ?''Piranhamesodon'' Kölbl-Ebert ''et al.'', 2018 ** Genus ?''Pseudopycnodus'' Taverne, 2003 ** Genus ?''Tergestinia'' Capasso, 2000 ** Genus ?''Thurmondella'' Thurmond, 1974 non 'Paramicrodon'' Thurmond, 1974 non de Meijere, 1913">Paramicrodon.html" ;"title="'Paramicrodon">'Paramicrodon'' Thurmond, 1974 non de Meijere, 1913** Genus ?''Uranoplosus'' le Sauvage, 1879 ** Genus ?''Woodthropea'' Swinnerton, 1925 **Family ?Hadrodontidae Thurmond & Jones, 1981 *** Genus ''Hadrodus'' Leidy, 1858 'Propenser'' Applegate, 1970">Propenser.html" ;"title="'Propenser">'Propenser'' Applegate, 1970**Family ? Gebrayelichthyidae Nursall & Capasso, 2004 *** Genus ''Gebrayelichthys'' Nursall & Capasso, 2004 *** Genus ''Maraldichthys'' Taverne & Capasso, 2014 **Family ?Gladiopycnodontidae Taverne & Capasso, 2013 *** Genus '' Arduafrons'' Frickhinger, 1991 *** Genus ''

Eomesodon ''Eomesodon'' is an extinct genus of prehistoric ray-finned fish. It lived during the Late Triassic and Jurassic. See also * Prehistoric fish * List of prehistoric bony fish A ''list'' is any set of items in a row. List or lists may also ...

'' Woodward, 1918 *** Genus '' Gladiopycnodus'' Taverne & Capasso, 2013 *** Genus '' Joinvillichthys'' Taverne & Capasso, 2014 ** Genus ''

Micropycnodon ''Micropycnodon'' is an extinct genus of prehistoric ray-finned fish that lived during the Santonian. See also * Prehistoric fish * List of prehistoric bony fish A ''list'' is any set of items in a row. List or lists may also refer to: ...

'' Hibbard & Graffham, 1945 'Pycnomicrodon'' Hibbard & Graffham, 1941 non Hay, 1916">Pycnomicrodon.html" ;"title="'Pycnomicrodon">'Pycnomicrodon'' Hibbard & Graffham, 1941 non Hay, 1916*** Genus ''Monocerichthys'' Taverne & Capasso, 2013 *** Genus ''Pankowskichthys'' Taverne & Capasso, 2014 *** Genus ''Paramesturus'' Taverne, 1981 *** Genus ''Rostropycnodus'' Taverne & Capasso, 2013 *** Genus '' Stenoprotome'' Hay, 1903 **Family Mesturidae Nursall, 1996 *** Genus '' Mesturus'' Wagner, 1862 **Family Gyrodontidae Berg, 1940 *** Genus '' Gyrodus'' Agassiz, 1833 **Family Brembodontidae Tintori, 1981 rembodidae; Gibbodontidae Tintori, 1981*** Genus '' Brembodus'' Tintori, 1981 *** Genus '' Gibbodon'' Tintori, 1981 **Family

Coccodontidae Coccodontidae is a family of extinct pycnodontid fish that lived during the lower Cenomanian. The various genera had massive, curved spines. The family is composed of five genera, the type genus, ''Coccodus'', '' Paracoccodus'' which was split ...

Berg, 1940 rewavasiidae Nursall, 1996 *** Genus '' Coccodus'' Pictet, 1850 *** Genus '' Corusichthys'' Taverne & Capasso, 2014 *** Genus '' Hensodon'' Kriwet, 2004 *** Genus '' Ichthyoceros'' Gayet, 1984 *** Genus '' Paracoccodus'' Taverne & Capasso, 2014 *** Genus '' Trewavasia'' White & Moy-Thomas, 1941 'Xenopholis'' Davis, 1887 non Peters, 1869; ''Xenopholoides">Xenopholis.html" ;"title="'Xenopholis">'Xenopholis'' Davis, 1887 non Peters, 1869; ''Xenopholoides'' Fowler, 1958] **Family Pycnodontidae Agassiz, 1833 corrig. Bonaparte, 1845 [Nursalliidae Bloy, 1987; Sphaerodontidae Giebel, 1846; Palaeobalistidae Blot, 1987; Proscinetidae Gistel, 1848; Gyronchidae] *** Genus '' Abdobalistum'' Poyato-Ariza & Wenz, 2002 *** Genus '' Anomiophthalmus'' Costa, 1856 *** Genus '' Anomoedus'' Forir, 1887 *** Genus ''

Acrotemnus ''Acrotemnus'' is an extinct genus of prehistoric ray-finned fish that lived during the Late Cretaceous epoch.The genus has single species Acrotemnus faba. See also * Prehistoric fish * List of prehistoric bony fish A ''list'' is any set of i ...

'' Agassiz 1836, *** Genus '' Akromystax'' Poyato-Ariza & Wenz, 2005 *** Genus ''

Coelodus ''Coelodus'' is an extinct genus of fish in the family Pycnodontidae from the Late Jurassic to early Paleocene (Danian). Fossils of the genus have been found in:Flagellipinna'' Cawley & Kriwet, 2019 *** Genus ''

Macropycnodon ''Macropycnodon'' is an extinct genus of ray-finned fish which existed in New Mexico ) , population_demonym = New Mexican ( es, Neomexicano, Neomejicano, Nuevo Mexicano) , seat = Santa Fe , LargestCity = Albuquerque , LargestMetro = T ...

'' Shimada, Williamson & Sealey, 2010 *** Genus '' Macromesodon'' Blake 1905 non Lehman, 1966 'Mesodon'' Wagner, 1851 non Rafinesque, 1821; ''Gyronchus">Mesodon.html" ;"title="'Mesodon">'Mesodon'' Wagner, 1851 non Rafinesque, 1821; ''Gyronchus'' Agassiz, 1839; ''Apomesodon'' Poyato-Ariza & Wenz, 2002] *** Genus ''Neoproseinetes'' De Figueiredo & Silva Santos, 1990 *** Genus ''Nursallia'' Blot, 1987 *** Genus ''Ocloedus'' Poyato-Ariza & Wenz, 2002 *** Genus '' Oropycnodus'' Poyato-Ariza & Wenz, 2002 *** Genus ''

Palaeobalistum ''Palaeobalistum'' is an extinct genus of prehistoric ray-finned fish which ranged from the Cretaceous to Eocene periods. Etymology The Latin genus name derives from a Greek word meaning "thick tooth". Species The following species have be ...

'' Taverne ''et al.'', 2015 *** Genus '' Paranursallia'' Taverne ''et al.'', 2015 *** Genus '' Phacodus'' Dixon, 1850 *** Genus ''

Polazzodus ''Polazzodus'' is an extinct pycnodontid from the late Cretaceous (early Santonian) of the Polazzo locality of northeastern Italy. The paleoenvironment of Polazzo was a large marine carbonate platform and shallow internal lagoons formed from ru ...

'' Poyoto-Ariza, 2010 *** Genus ''

Polygyrodus ''Polygyrodus'' is an extinct genus of prehistoric ray-finned fish that lived during the Late Cretaceous epoch. The name is a combination of the Greek words poly (many), gyro (round), and (tooth). See also * Prehistoric fish * List of prehist ...

'' White, 1927 *** Genus ''

Potiguara The Potiguara (also Potyguara or Pitiguara) are an indigenous people of Brazil. The Potiguara people live in Paraíba, in the municipalities of Marcação, Baía da Traição and Rio Tinto. Their population numbers sixteen thousand indivi ...

'' Machado & Brito, 2006 *** Genus ''

Proscinetes ''Proscinetes'' is an extinct genus of prehistoric ray-finned fish from the Jurassic. See also * Prehistoric fish * List of prehistoric bony fish A ''list'' is any set of items in a row. List or lists may also refer to: People * List ( ...

'' Gistl, 1848 Microdon'' Agassiz, 1833 non Meigen, 1803 non Fritsch, 1876 non Conrad, 1842 non Gistl, 1848 non Dixon, 1850; ''Polypsephis">Microdon_(fish).html" ;"title="'Microdon (fish)">Microdon'' Agassiz, 1833 non Meigen, 1803 non Fritsch, 1876 non Conrad, 1842 non Gistl, 1848 non Dixon, 1850; ''Polypsephis'' Hay, 1899] *** Genus ''Pycnomicrodon'' Hay 1916 non Hibbard & Graffham, 1941 *** Genus ''Pycnodus'' Agassiz, 1833 *** Genus ''Rhinopycnodus'' Taverne & Capasso, 2013 *** Genus ''

Sphaerodus ''Lepidotes'' (from el, λεπιδωτός , 'covered with scales') (previously known as ''Lepidotus'') is an extinct genus of Mesozoic ray-finned fish. It has been considered a wastebasket taxon, characterised by "general features, such as thi ...

'' Agassiz, 1833 *** Genus '' Sphaeronchus'' Stinton & Torrens, 1967 *** Genus '' Stenamara'' Poyato-Ariza & Wenz, 2000 *** Genus '' Stemmatias'' Hay, 1899 'Stemmatodus'' St. John & Worthen, 1875 non Heckel, 1854 non">Stemmatodus.html" ;"title="'Stemmatodus">'Stemmatodus'' St. John & Worthen, 1875 non Heckel, 1854 non*** Genus ''Stemmatodus'' Heckel, 1854 non St. John & Worthen, 1875 non *** Genus ''Sylvienodus'' Poyato-Ariza & Wenz, 2013 *** Genus ''Tamanja'' Wenz, 1989 *** Genus '' Tepexichtys'' Applegate, 1992 *** Genus ''

Tibetodus ''Tibetodus'' is an extinct genus of prehistoric ray-finned fish that lived during the Late Jurassic epoch. See also * Prehistoric fish * List of prehistoric bony fish A ''list'' is any set of items in a row. List or lists may also refer t ...

'' Young & Liu, 1954 *** Genus '' Turbomesodon'' Poyato-Ariza & Wenz, 2004 Macromesodon'' Lehman, 1966 non Blake, 1905">' Macromesodon'' Lehman, 1966 non Blake, 1905*** Genus '' Typodus'' Quenstedt, 1858 *** Genus '' Abdobalistum'' Poyato-Ariza & Wenz, 2002 **Family '' incertae sedis'' *** Genus ''

Agassizilia ''Agassizilia'' is an extinct genus of pycnodont fishes from the mid-Cretaceous ( Albian-Cenomanian The Cenomanian is, in the ICS' geological timescale, the oldest or earliest age of the Late Cretaceous Epoch or the lowest stage of the Upper C ...

'' Cooper and Martill, 2020 *** Genus '' Neomesturus'' Cooper and Martill, 2020Cooper, 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

References

** Capasso, Luigi (2021). "Pycnodonts: An overwiew and new insights in the Pycnodontomorpha Nursall, 2010". Occasional Paper of the University Museum of Chieti, Monographic Publication, 1: 1-223. {{Taxonbar, from=Q1787823 Prehistoric ray-finned fish orders