Fadenia
| Fadenia | ||||||||||||
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Reconstruction of Fadenia |
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| Temporal occurrence | ||||||||||||
| Pennsylvania to Lower Triassic | ||||||||||||
| 314.6 to 247.2 million years | ||||||||||||
| Locations | ||||||||||||
| Systematics | ||||||||||||
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| Scientific name | ||||||||||||
| Fadenia | ||||||||||||
| Nielsen , 1932 |
Fadenia is an extinct genus of cartilaginous fish that has been found in fossil records in North Americafrom the Pennsylvania ("Upper Carboniferous") to the Lower Triassic . It belongs to the Holocephali and led a predatory way of life as a nectic carnivore.
Systematics
Within the Holocephali, Fadenia belongs to the Caseodontidae family within the Eugeneodontida . The genus contains three known species - Fadenia crenulata Nielsen, 1932, F. gigas Eaton 1962, and F. uroclasmato Mutter and Neuman, 2008.
features
In addition to the two very important pectoral fins, Fadenia possessed a strong, forward-offset, spineless dorsal fin , the base of which was supported by a triangular cartilage plate. The pectoral fin had a long, rearwardly directed fin axis, but did not quite reach the pectoral fin length of the Symmoriida . The strong caudal fin was homocerk and outwardly symmetrical - characteristic of a fast swimming, active predator. The caudal fin was also stiffened by large cartilage plates. Abdominal and anal fins were missing, and there was no pelvic belt either.
Fadenia's streamlined body tapered like a spindle and thus resembled the physique of the Cladoselachidae and the Symmoriida. It reached over a meter in length. The skull was long and narrowed at the sides. The otico-occipital section (ear region) was only very short, but the ethmoid bone (nasal region) was designed as a long rostrum . The entire upper jaw formed a thorn-like, pointed rostrum and protruded over the lower jaw. The eyes were very big. There were five slit-shaped gill slits behind the lower jaw . The gill arches lay behind the skull, which is characteristic of plate gills. It is assumed that the palatoquadratum was fused directly with the cerebral skull, as is usual with the holocephali , and that the upper teeth therefore sit directly on the neurocranium . Zangerl (1981), however, is of the opinion that Fadenia had completely lost the palatoquadratum . According to Zangerl, the teeth of the lower jaw show a spiral gear at the tip. The subsequent lower jaw was covered by small, plaster-like tooth plates.
Occurrence
- East Greenland : Wordie Creek Formation
- Canada : British Columbia - Sulfur Mountain Formation
- United States : Missouri - Upper Cherokee Shale
literature
- Bendix-Almgreen, SE: Fossil fishes from the marine Late Palaeozoic of Holm Land - Amdrup Land, north-east Greenland . In: Meddelelser om Grønland . tape 195 , 1975, p. 3-38 .
- Robert L. Carroll: Vertebrate Paleontology and Evolution . WH Freeman and Company, New York 1988, ISBN 0-7167-1822-7 .
- Zangerl, R .: Chondrichthyes 1, Paleozoic Elasmobranchi . In: HP Schultze (Ed.): Handbook of Paleoichthyology . Gustav Fischer, Stuttgart, New York 1981, pp. 116 .
Individual evidence
- ^ E. Nielsen: Permo-Carboniferous fishes from east Greenland . In: Meddelelser om Grønland . tape 86 (3) , 1932, pp. 1-63 .
- ^ TH Eaton: Teeth of Edestid Sharks . In: University of Kansas Publications Museum of Natural History . tape 12 (8) , 1962, pp. 347-362 .
- ^ Raoul J. Mutter and Andrew G. Neuman: New eugeneodontid sharks from the Lower Triassic Sulfur Mountain Formation of Western Canada . In: Geological Society, London, Special Publications . tape 295 , 2008, p. 9-41 , doi : 10.1144 / SP295.3 . (Digitized version)
- ^ Robert L. Carroll: Vertebrate Paleontology and Evolution . WH Freeman and Company, New York 1988, ISBN 0-7167-1822-7 .