Palaeoniscoid

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 each other) it has been suggested that some may belong to the crown group, with some of these possibly related to Cladistia (containing bichirs) and/or Chondrostei (which contains sturgeons and paddlefish). Many palaeoniscoids share a conservative body shape and a similar arrangement of skull bones, though paleoniscoids as a whole exhibit considerable diversity in body shape.