Carboniferous fish

Acanthodiformes (alternatively spelled Acanthodida) is an order of "acanthodians" which lived from the Early Devonian to the Early Permian. Members of the order have been found worldwide in rocks preserving both freshwater and marine environments, and are distinguished from other acanthodians by the presence of only a single dorsal fin and dorsal fin spine, and in most members a lack of teeth and well-developed gill rakers. Some acanthodiforms are presumed to have fed by filter-feeding, and had large mouths and gill arches. While they have been suggested to be close relatives of modern bony fi

Holoptychius (from , 'whole' and 'fold') is an extinct genus of porolepiform lobe-finned fish from the Middle Devonian to Carboniferous (Mississippian) periods. It is known from fossils worldwide. The genus was first described by Louis Agassiz in 1839.