Symmoriida
Symmoriida | ||||||||||||
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Live reconstruction of Symmorium sp. |
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Temporal occurrence | ||||||||||||
Oberdevon to Oberkarbon | ||||||||||||
Systematics | ||||||||||||
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Scientific name | ||||||||||||
Symmoriida | ||||||||||||
Zangerl , 1981 |
The Symmoriida or Symmoriiformes are an extinct order of shark-like cartilaginous fish whose fossil remains were found in marine deposits of the Upper Paleozoic Era .
features
The fish are similar to the Cladoselachia . Like these, the Symmoriida lacked the anal fin , their caudal fin was fork-shaped and also externally symmetrical. The pectoral fins were drawn out like a whip. In contrast to the Cladoselachia, they only had one dorsal fin , which stood over the pelvic fins , and no normally developed fin spines. Her teeth were cladodont. The Symmoriida were only scaled along the lateral line organ . The clasps were already well developed but differed from those of modern sharks.
Subtaxa
- Symmoriidae , without fin spines.
- Falcatidae , the dorsal fin spine of males, is formed into a forward-facing hook-shaped organ with a tooth-covered surface.
- Stethacanthidae , the dorsal spine of males, is formed into a brush-shaped organ with a tooth-covered surface.
literature
- Robert L. Carroll: Paleontology and Evolution of the Vertebrates . Thieme, Stuttgart (1993), ISBN 3-13774-401-6
- Joseph S. Nelson : Fishes of the World . John Wiley & Sons, 2006, ISBN 0-471-25031-7
Web links
- Symmoriida Palæos
- Symmoriida The Paleobiology Database
- Falcatus falcatus Fossil Fishes of Bear Gulch
Falcatus falcatus , living reconstruction of ♀ (above) and ♂
Stethacanthus altonensis , life reconstruction of ♂ and ♀