Acanthodiformes

Acanthodiformes Temporal range: Early Devonian–Early Permian PreꞒ Ꞓ O S D C P T J K Pg N
Fossil of Acanthodes, a member of the family Acanthodidae
Fossil of Cheiracanthus, a member of the family Cheiracanthidae
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Chordata
Class:	†Acanthodii
Order:	†Acanthodiformes Berg, 1940
Families
Acanthodidae Cheiracanthidae Mesacanthidae Howittacanthidae?

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 fish due to similarities in their skulls, recent research indicates that, like other acanthodians, they are more likely to be stem-group cartilaginous fish.