Eugeneodontida
| Eugeneodontida | ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
Fadenia crenulata from the Permian of Greenland |
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| Temporal occurrence | ||||||||||||
| Upper Devonian to Triassic | ||||||||||||
| 360 to 220 million years | ||||||||||||
| Systematics | ||||||||||||
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| Scientific name | ||||||||||||
| Eugeneodontida | ||||||||||||
| Zangerl , 1981 |
The Eugeneodontida or Eugeneodontiformes are an order of shark-like, fossil cartilaginous fish that lived from the Upper Devonian to the end of the Triassic . Their characteristic features are very large teeth in the lower jaw, with replacement teeth that were formed on a large tooth spiral. The teeth that are in use are arranged in a plaster-like manner and, similar to many rays , served to crush hard-shelled prey.
Systematics
The Eugeneodontida are divided into two systematic groups, the Caseodontoidea and the Edestoidea:
The Caseodontoidea had a spindle-shaped, shark -like body with only one dorsal fin , which sat directly above the pectoral fins and which was supported by a large, triangular cartilage plate. The caudal fin was externally symmetrical and was also supported by strong cartilage. Pelvic girdle and pelvic fins are absent. Among them u. a. the well-known genus Fadenia , as well as Caseodus and Ornithoprion .
The Edestoidea probably had a skeleton that was only slightly calcified and unsuitable for fossilization . Apart from the teeth and the tooth-bearing parts of the skull, little is known of them. Among them were u. a. the genera Edestus , Sarcoprion and Helicoprion .
The external systematic position of the eugeneodontida is still uncertain. Nelson it provides provisionally to the Holocephali , including the now extant chimaeras (Chimaeriformes) are, with whom they have some features of the skull anatomy together. Other scientists see them outside of Holocephali and Elasmobranchii .
Caseodus , graphic reconstruction
Edestus protopirata , hypothetical reconstruction
Sarcoprion edax , hypothetical reconstruction
Helicoprion bessonovi , hypothetical reconstruction
literature
- Robert L. Carroll: Paleontology and Evolution of the Vertebrates , Thieme, Stuttgart (1993), ISBN 3-13-774401-6 .
- Joseph S. Nelson : Fishes of the World. 4th edition. John Wiley & Sons, Hoboken NJ et al. 2006, ISBN 0-471-25031-7 .
