Gyroptychius
Extinct genus of tetrapodomorphs
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Gyroptychius is an extinct genus of freshwater osteolepiform tetrapodomorphs from the middle to late Devonian period. It is the only known member of the family Gyroptychiidae.[1] They were found throughout much of what is now northern Europe and Greenland, with more dubious records from Canada, Australia & Antarctica.
| Gyroptychius Temporal range: | |
|---|---|
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| Specimen of G. agassizi, Naturalis Biodiversity Center | |
Scientific classification  | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | †Osteolepidida |
| Order: | †Osteolepiformes |
| Family: | †Gyroptychiidae Berg, 1958 |
| Genus: | †Gyroptychius McCoy, 1848 |
| Type species | |
| †Diplopterus agassizi Traill, 1841 | |
| Species | |
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See text | |
| Synonyms | |
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The following species are known:[1][2]
- †G. agassizi (Traill, 1841) (type species) - Eifelian to Givetian of Scotland, including the Orkney Isles[3] (Stromness Flagstone and Caithness Flagstone) (=Glyptolepis microlepidotus Agassiz, 1844)[4][5]
- †G. dolichotatus Jarvik, 1985 - Eifelian of Greenland (Nathorst Fjord Formation)[6][7]
- †G. elgae Vorobyeva, 1977 - Givetian of Estonia (Burtnieki Formation)
- †G. groenlandicus Jarvik, 1950 - Givetian of Greenland (Nathorst Fjord Formation)[7]
- †G. milleri Jarvik, 1948 - Givetian of Scotland (Caithness Flagstone) & Estonia (=Gyroptychius pauli Vorobyeva, 1977)[8]
The following, more dubious species are also known: G.? kiaeri Jarvik, 1949 (Devonian of Norway), G.? taylori Jessen, 1968 (Devonian of Canada), G.? australis Young & Gorter, 1981 (Early Devonian of Australia), and G.? antarcticus (Woodward, 1921) (Famennian-aged Aztec Siltstone of Antarctica). Of these, G.? australis may potentially be referable to the East Asian genus Kenichthys[9], while G. antarcticus is a nomen nudum.[10]
Gyroptychius was a fast riverine predator with an elongated body about 30 centimetres (12 in) long. As its eyes were relatively small, it is presumed to have hunted by smell rather than sight. Gyroptychius had short jaws which gave it a powerful bite. All its fins except the pectorals were moved to the back to the body, increasing the power of the tail while swimming.[11]
