Pachycormiformes is an extinct order of marine ray-finned fish known from the Early Jurassic to the end of the Cretaceous. It only includes a single family, Pachycormidae. They were characterized by having serrated pectoral fins (though more recent studies demonstrated that fin shape diversity in this group was high), reduced pelvic fins and a bony rostrum. Their exact relations with other fish are unclear, but they are generally considered to be teleosteomorphs, more closely related to teleosts than to Holostei. Pachycormiformes are morphologically diverse, containing both tuna and

swordfish Swordfish (''Xiphias gladius''), also known as broadbills in some countries, are large, highly migratory predatory fish characterized by a long, flat, pointed bill. They are a popular sport fish of the billfish category, though elusive. Swordfis ...

-like carnivorous forms, as well as edentulous suspension-feeding forms, with the latter including the largest ray finned fish known to have existed, ''

Leedsichthys ''Leedsichthys'' is an extinct genus of pachycormid fish that lived in the oceans of the Middle to Late Jurassic.Liston, JJ (2004). An overview of the pachycormiform ''Leedsichthys''. In: Arratia G and Tintori A (eds) Mesozoic Fishes 3 - System ...

,'' with an estimated maximum length of 16 metres.

Synapomorphies

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"

Relationships

Pachycormiformes are generally interpreted as members of

Teleosteomorpha Neopterygii (from Greek νέος ''neos'' 'new' and πτέρυξ ''pteryx'' 'fin') is a subclass of ray-finned fish (Actinopterygii). Neopterygii includes the Holostei and the Teleostei, of which the latter comprise the vast majority of extant f ...

, the group that includes all fish more closely related to modern teleosts than to Holostei (the group containing

bowfin The bowfin (''Amia calva'') is a bony fish, native to North America. Common names include mudfish, mud pike, dogfish, grindle, grinnel, swamp trout, and choupique. It is regarded as a relict, being the sole surviving species of the Halecomorphi ...

and gars), often they have been considered to be the

sister group In phylogenetics, a sister group or sister taxon, also called an adelphotaxon, comprises the closest relative(s) of another given unit in an evolutionary tree. Definition The expression is most easily illustrated by a cladogram: Taxon A and t ...

of the

Aspidorhynchiformes Aspidorhynchiformes (from New Latin "shield-snout forms") is an extinct order of ray-finned fish. It contains only a single family, the Aspidorhynchidae. Members of the group are noted for their elongated, conical rostrums, of varying length, fo ...

Gallery

Taxonomy

Taxonomy according to Cooper ''et al.'' (2022): * ''

Euthynotus ''Euthynotus'' is an extinct genus of prehistoric bony fish that lived during the early Toarcian stage of the Early Jurassic epoch. It is generally considered the basalmost pachycormiform. Species ''Euthynotus'' has two species classified wit ...

'' Wagner, 1860 * '' Haasichthys'' Delsate, 1999 * '' Notodectes'' Dolgopol de Saez, 1949 * ''

Pseudoasthenocormus ''Pseudoasthenocormus'' is an extinct genus of ray-finned fish belonging to the family Pachycormidae. It contains one species, ''P. retrodorsalis''. It lived during the upper Jurassic (Kimmeridgian– Tithonian, about 152–148 million years ago) ...

'' * ''

Sauropsis ''Sauropsis'' (from el, σαῦρος , 'lizard' and el, ὄψῐς 'looking') is an extinct genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In ...

'' Agassiz, 1843 * Hypsocorminae Vetter, 1881 ** ''

Australopachycormus ''Australopachycormus'' is an extinct genus of marine pachycormiform fish. It is only known from the type species, ''A. hurleyi'', from the Early Cretaceous ( Albian) Toolebuc Formation of Queensland, Australia. Like the related '' Protosphyrae ...

'' Kear, 2007 ** ''

Hypsocormus ''Hypsocormus'' (from el, ῠ̔́ψος , 'height' and el, κορμός 'timber log') is an extinct genus of pachycormid fish from the Middle to Late Jurassic of Europe. Fossils have been found in Germany, France and the UK. The type specie ...

'' Wagner, 1860 ** '' Kaykay'' Gouiric-Cavalli & Arratia, 2022 ** ''

Orthocormus ''Orthocormus'' is an extinct genus of prehistoric pachycormiform bony fish. It is known from three species found in Late Jurassic (Kimmeridgian) aged plattenkalk deposits in Bavaria, Germany. The species "'' Hypsocormus" tenuirostris'' Woodwar ...

'' Weitzel, 1930 ** '' Protosphyraena'' Leidy, 1857 ** '' Simocormus'' Maxwell ''et al.'', 2020 * Asthenocorminae Cooper ''et al.'', 2022 ** '' Germanostomus'' Cooper ''et al.'', 2022 ** ''

Ohmdenia ''Ohmdenia'' is an extinct genus of prehistoric bony fish that lived from the Toarcian stage of the Early Jurassic epoch. ''Ohmdenia'' was first described in 1953 by B. Hauff, based on a fossil found in the well-known Posidonia Shale in Holzma ...

'' Hauff, 1953 ** '' Pachycormus''? Agassiz, 1833 ** ''

Saurostomus ''Saurostomus'' is an extinct genus of prehistoric bony fish that lived during the early Toarcian stage of the Early Jurassic epoch. See also * Prehistoric fish The evolution of fish began about 530 million years ago during the Cambrian ...

'' Agassiz, 1843 ** Suspension-feeding clade *** ''

Asthenocormus ''Asthenocormus'' is an extinct genus of pachycormiform ray-finned fish. A member of the edentulous suspension feeding clade within the Pachycormiformes, fossils have been found in the Upper Jurassic plattenkalks of Bavaria, Germany.' See ...

'' Woodward, 1895 *** ''

Bonnerichthys ''Bonnerichthys'' is a genus of fossil fishes within the family Pachycormidae that lived during the Late Cretaceous Period Fossil remains of this taxon were first described from the Smoky Hill Member of the Niobrara Chalk Formation of Kansas (L ...

'' Friedman ''et al.'', 2010 *** ''

'' Woodward, 1889 *** ''

Martillichthys ''Martillichthys'' is an extinct genus of pachycormiform fish, known from the late Middle Jurassic ( Callovian) Oxford Clay, England. It is a member of the suspension feeding clade within the Pachycormiformes, most closely related to ''Asthenoc ...

'' Liston, 2008 *** ''

Rhinconichthys ''Rhinconichthys'' is an extinct genus of bony fish which existed during the upper Cretaceous period. Along with its close cousins the great-white-shark-sized or larger '' Bonnerichthys'' and the immense ''Leedsichthys'', ''Rhinconichthys'' f ...

'' Friedman ''et al.'', 2010 Cladistics according to Friedman ''et al.'' (2010).

References

{{Taxonbar, from=Q1227671 Late Triassic first appearances Maastrichtian extinctions Prehistoric ray-finned fish orders