Pachycormiformes

Pachycormiformes
Temporal range: Early Jurassic - Late Cretaceous, Toarcian–Maastrichtian
Skeleton of Pachycormus
Skeleton of Orthocormus
Scientific classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Actinopterygii
Infraclass: Teleosteomorpha
Division: Aspidorhynchei
Order: Pachycormiformes
Berg 1937
Family: Pachycormidae
Woodward, 1895
Type genus
Pachycormus
Agassiz, 1833
Genera

See text

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. 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. Pachycormiformes are morphologically diverse, containing both tuna and swordfish-like carnivorous forms, as well as edentulous suspension-feeding forms.

Description

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". Pachycormiformes varied substantially in size, from medium-sized fishes around 40–111 centimetres (1.31–3.64 ft) 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 16 metres (52 ft).

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.

Gallery

Taxonomy

Taxonomy according to Cooper et al. (2022):

Cladistics according to Friedman et al. (2010).

Pachycormiformes

Euthynotus

Hypsocormus insignis

"Hypsocormus" tenuirostris

Orthocormus

Australopachycormus

Protosphyraena

Pachycormus

Suspension feeding clade

Asthenocormus titanius

Martillichthys renwickae

Bonnerichthys gladius

Leedsichthys problematicus

Rhinconichthys taylori


This page was last updated at 2024-02-09 09:20 UTC. Update now. View original page.

All our content comes from Wikipedia and under the Creative Commons Attribution-ShareAlike License.


Top

If mathematical, chemical, physical and other formulas are not displayed correctly on this page, please useFirefox or Safari