Semionotiformes

Semionotiformes is an order of ray-finned fish known from the Middle Triassic (Anisian) to the Late Cretaceous (Maastrichtian). Their closest living relatives are gars (Lepisosteidae), with both groups belonging to the clade Ginglymodi within the Holostei. Many members of the family Macrosemiidae (which are usually included in Semionotiformes but sometimes placed in their order), had elongated dorsal fins, often associated with an adjacent area of skin which was free of scales. These fins were likely undulated for use in precision swimming. The body morphology of macrosemiids suggests that they were slow swimmers who were capable of maneuvering around complex topography, such as reef environments.

Classification

Order †Semionotiformes Arambourg & Bertin 1958 sensu López-Arbarello 2012
Genus ?†Orthurus Kner 1866
Genus †Sangiorgioichthys Tintori & Lombardo 2007
Genus †Luoxiongichthys Wen et al. 2011
Genus †Aphanepygus Bassani 1879
Genus †Austrolepidotes Bocchino, 1974
Genus †Corunegenys Wade, 1942
Genus †Placidichthys Brito 2000
Family ?†Hadrodontidae Thurmond and Jones, 1981 (alternately considered a pycnodont)
Genus ?†Hadrodus Leidy, 1857 (alternately considered a pycnodont)
Family †Pleurolepididae Lütken 1871
Genus †Pleurolepis Agassiz 1863 non Quenstedt 1852
Family †Macrosemiidae Wagner 1860a corrig. Cope 1889 sensu Murray & Wilson 2009 [Macrosemii Wagner 1860a]
Genus †Eusemius Vetter 1881
Genus †Blenniomoeus Costa 1850 [Calignathus Costa 1853]
Genus †Enchelyolepis Woodward 1918
Genus †Palaeomacrosemius Ebert, Lane & Kolbl-Ebert 2016
Genus †Voelklichthys Arratia & Schultze 2012
Genus †Notagogus Agassiz 1833-1844 [Neonotagogus Bravi 1994]
Genus †Agoultichthys Murray & Wilson 2009
Genus †Histionotus Egerton 1854
Genus †Propterus Agassiz 1833-1844 [Rhynchoncodes Costa 1850]
Genus †Macrosemiocotzus González-Rodríguez, Applegate & Espinosa-Arrubarrena 2004
Genus †Legnonotus Egerton 1853
Genus †Macrosemius Agassiz 1833-1844
Family †Semionotidae Woodward 1890 sensu López-Arbarello 2012
Genus †Semionotus Agassiz 1832 (Usually considered a wastebasket taxon)