Acanthodes

''Acanthodes'' (from , 'provided with spines') is an extinct genus 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.

Description

The largest species of ''Acanthodes'' like ''Acanthodes confusus'' and ''Acanthodes splendidus'' grew to lengths of at least , while some species like ''Acanthodes ultimus'' were much smaller, reaching a total body length of only .Heidtke, U.H.J.
Revision der unterpermischen Acanthodier (Acanthodii: Pisces) des südwestdeutschen Saar-Nahe-Beckens
evision of the Early Permian acanthodians (Acanthodii : Pisces ) from the southwest german Saar -Nahe Basin ''Mitt. Pollich.'', 2011, no. 95, pp. 15–41. (In German with translation of species descriptions into English) 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. Species of ''Acanthodes'' differ from each other in the degree of body elongation and the size and shape of the fins. ''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. 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.

Ecology

The various species of ''Acanthodes'' are known to have inhabited freshwater lakes, as well as saline lagoons. ''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 '' Glanochthon''. ''Acanthodes'' was likely capable of opening its jaws wide as an adaptation to suspension feeding, with the jaws possibly also rotating outwards during opening in order to increase gape.

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-group Chondrichthyes. Within the "Acanthodii", ''Acanthodes'' is traditionally placed within the Acanthodiformes, which is now also considered to be paraphyletic.

Species

After Beznosov, 2009 and Heidtke, 2011

* ''Acanthodes bronni'' Agassiz, 1833 (type), Meisenheim Formation, Germany, Lower Permian,
* ''Acanthodes bourbonensis'' Heidtke, 1996, Early Permian, France,
* ''Acanthodes boyi'' Heidtke, 1993, Meisenheim Formation, Early Permian, Germany,
* ''Acanthodes bridgei'' Zidek, 1976, Hamilton Quarry, Late Carboniferous (Stephanian), Kansas, USA,
* ''Acanthodes confusus'' Heidtke, 2011, Meisenheim Formation, Early Permian, Germany,
* ''Acanthodes fritschi'' Zajic, 1998, Late Carboniferous (Stephanian), Czech Republic,
* ''Acanthodes gracilis'' (Beyrich, 1848), Early Permian, Czech Republic, Poland and Germany,
* ''Acanthodes kinneyi'' Zidek, 1992, Atrasado Formation, Late Carboniferous (Stephanian), New Mexico, USA,
* ''Acanthodes lopatini'' Rohon, 1889, Early Carboniferous (Tournaisian), southern Krasnoyarsk Krai, Russia,
* ''Acanthodes lundi'' Zidek, 1980, Bear Gulch Limestone, Early Carboniferous (Namurian), Montana, USA,
* ''Acanthodes ovensi'' White, 1927, Early Carboniferous (Tournaisian), Scotland, although normally up to
* ''Acanthodes palatinensis'' Heidtke, 2011, Meisenheim Formation, Early Permian, Germany,
* ''Acanthodes pollichiae'' Heidtke, 2011, Meisenheim Formation, Early Permian, Germany,
* ''Acanthodes relsbergensis'' Heidtke, 2011, Meisenheim Formation, Early Permian, Germany,
* ''Acanthodes ruhinensis'' Heidtke, 2011, Meisenheim Formation, Early Permian, Germany,
* ''Acanthodes sippeli'' Heidtke, 1996, Late Carboniferous (Namurian), Germany,
* ''Acanthodes splendidus'' Heidtke, 2011, Meisenheim Formation, Early Permian, Germany,
* ''Acanthodes stambergi'' Zajic, 2005, Early Permian, Czech Republic,
* ''Acanthodes ultimus'' Heidtke, 2011, Donnersberg Formation, Early Permian, Germany,
* ''Acanthodes wardi'' Egerton, 1866, Late Carboniferous (Westphalian), England and Scotland,

Indeterminate or dubious species

*''Acanthodes australis'' Woodward, 1906, Mansfield Basin, Australia, Early Carboniferous,
*''Acanthodes beecheri'' Eastman 1902, Mazon Creek, Illinois, USA, Late Carboniferous, , listed in Schnetz (2022)
* ''Acanthodes guizhouensis'' Wang Shitao & Turner 1984, Early Carboniferous (Tournaisian), Guizhou, China
* ''Acanthodes latgalica'' Lyarskaya & Luksevic 1992, Early Devonian (Emsian), Baltic
* ''Acanthodes luedersensis'' (Dalquest ''et'' ''al''., 1988), Early Permian, Texas, USA
* ''Acanthodes nitidus'' Woodward 1891, Early Carboniferous (Visean), Scotland, listed in Schnetz (2022)
* ''Acanthodes punetatus'' Fritsch 1893, Early Permian, Czech Republic
* ''Acantodes sulcatus'' Agassiz, 1835, Early Carboniferous (Visean), Scotland, , listed in Schnetz (2022)

''Acanthodes tholeyi'' Heidtke, 1990 from Early Permian, Germany is later assigned to genus '' Westrichus''.

References

* Parker, Steve. Dinosaurus: the complete guide to dinosaurs. Firefly Books Inc, 2003. Pg. 60

External links

entry at the Fossil Museumentry at Saint Joseph's University

{{Taxonbar, from=Q2335100

Acanthodiformes
Carboniferous cartilaginous fish
Permian cartilaginous fish
Paleozoic fish of North America
Paleozoic fish of Europe
Prehistoric fish of Australia
Taxa named by Louis Agassiz
Fossil taxa described in 1833