Pachycormiformes

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". Pachycormiformes varied substantially in size, from medium-sized fishes around in length like the macropredator Pachycormus, to the largest known ray-finned fish, the suspension feeding Leedsichthys, which is estimated to have reached a maximum length of around . == 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. 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. • Order Pachycormiformes • ?Eugnathides Gregory, 1923 • Haasichthys Delsate, 1999 • Notodectes Dolgopol de Saez, 1949 • Superfamily Pachycormoidea • Family Pachycormidae Lyddeker, 1889 • Germanostomus Cooper et al., 2022 • Pseudoasthenocormus Lambers, 1992 • Sauropsis Agassiz, 1843 • Simocormus Maxwell et al., 2020 • Subfamily Protosphyraeninae Woodward, 1888 • Erisichthe Cope, 1872 }} == 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 ==References==