Acanthodes (from
Greek: ἄκανθώδηςakanthódis, 'provided with spines')[2] is an
extinctgenus of
acanthodian fish. Species have been found in Europe, North America, and Asia, spanning the
Early Carboniferous to the
Early Permian, making it one of the youngest known acanthodian genera.[3]
Description
Acanthodes grew to lengths of at least 41 centimetres (16 in).[4] The body was elongate and had a pair of pectoral fins, an unpaired dorsal fin far back on the body, with an unpaired long ventral/pelvic fin and an anal fin on the underside of the body, which like other acanthodians were supported by stiff spines at their front edges. The whole body was covered in scales, which varied in shape depending on their position. The vertebral column was typically unossified.[3]Acanthodes had no teeth and had long
gill rakers. Because of this, Acanthodes is presumed to have been a
suspension feeder, filtering
plankton from the water.[5] A specimen of Acanthodes bridgei was so well-preserved that traces of its eye tissue were sufficient to establish that Acanthodes had both rod and cone
photoreceptor cells, suggesting that it was capable of
color vision.[6]
Ecology
The various species of Acanthodes are known to have inhabited freshwater lakes,[7] as well as saline
lagoons.[8]Acanthodes bronni, which lived in freshwater lakes in southern Germany during the Early Permian, is known to have been fed upon by the
temnospondyl amphibians Archegosaurus and Cheliderpeton.[7]Acanthodes was likely capable of opening its jaws wide as an adaptation to suspension feeding.[9]
Taxonomy
The classification of acanthodians was historically contentious, however, in the 2010s based in part based on detailed studies of the skull of Acanthodes, it became widely accepted that acanthodians represented a
paraphyletic assemblage of
stem-groupChondrichthyes.[10][9] Within the "Acanthodii", Acanthodes is traditionally placed within the
Acanthodiformes, which is now also considered to be paraphyletic.[11]
^Zidek, Jiri (5 May 1976). "Kansas Hamilton Quarry (Upper Pennsylvanian) Acanthodes, with remarks on the previously reported North American occurrences of the genus". The University of Kansas Paleontological Contributions.
hdl:1808/3725. Paper 83.