Palaeonisciformes

Palaeoniscoids (also spelled paleoniscoid, or alternatively paleoniscids) are an extinct grouping of primitive ray-finned fish (Actinopterygii), spanning from the Silurian/Devonian to the Cretaceous. Though often assigned to their own order, the Palaeonisciformes (or superorder Palaeoniscimorpha), they are generally considered paraphyletic, but their exact relationships to living ray-finned fish are uncertain. While some and perhaps most palaeoniscoids likely belong to the stem-group of Actinopteryii (less closely related to modern ray-finned fish groups than all modern ray-finned fish are to

Palaeoniscum (from , 'ancient' and 'cod-fish' or 'woodlouse') is an extinct genus of ray-finned fish from the Middle to Late Permian period (Guadalupian-Lopingian) of England, Germany, Turkey, North America and Greenland, and possibly other regions. The genus was named Palaeoniscum in 1818 by Henri Marie Ducrotay de Blainville, but was later misspelled as Palaeoniscus by Blainville and other authors (notably Louis Agassiz). Palaeoniscum belongs to the family Palaeoniscidae.

Pteronisculus is an extinct genus of prehistoric ray-finned fish that lived during the Early Triassic and Middle Triassic epochs of the Triassic period worldwide.

thumb|left|Platysomus gibbosus thumb|left|Fossil of Platysomus circularis in the Field Museum of Natural History, Chicago

Gyrolepis is an extinct genus of prehistoric ray-finned fish from the Middle-Late Triassic epochs in what is now Europe. It is known both from complete specimens and isolated skeletal elements, such as scales or teeth. thumb|left|Isolated teeth and scales ascribed to Gyrolepis

225px|thumb|Restoration of Palaeoniscum freieslebeni showing the typical morphology of most taxa that have been referred to Palaeoniscidae Palaeoniscidae is an extinct family of "palaeoniscoid" ray-finned fishes (Actinopterygii). The family includes the genus Palaeoniscum and potentially other Palaeozoic and Mesozoic early actinopterygian genera. The name is derived from the Ancient Greek words παλαιός (palaiós, ancient) and ὀνίσκος (oniskos, 'cod-fish' or woodlouse).

Rhadinichthys is an extinct genus of prehistoric bony fish. It is known from several species that lived in the Late Devonian epoch, the Carboniferous period and the Cisuralian epoch (early Permian) in what is now Europe, South Africa, and North and South America. Some isolated scales from the Cisuralian of Europe (Belgium, France, Russia) were also referred to this genus.