Diplomystus
Diplomystus | ||||||||||||
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![]() Diplomystus dentatus |
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Temporal occurrence | ||||||||||||
Upper Cretaceous to Lower Eocene | ||||||||||||
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Systematics | ||||||||||||
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Scientific name | ||||||||||||
Diplomystus | ||||||||||||
Cope , 1877 |
Diplomystus ( synonym : Copeichthys Dollo, 1904) is an extinct genus of fish from the family Ellimmichthyidae from the kinship of the herring-like (Clupeiformes). With over 350,000 individual finds, the genus isthe second most common fish in the Eocene Fossil Butte Member in the North American Green River Formation after Knightia . Other finds that are dated to the Upper Cretaceous are from Lebanon.
features
Diplomystus was up to 65 cm long and had a relatively squat for herring Related body with a deep stomach, similar to the recent pristigasteridae (Pristigasteridae). The genus differs from other Ellimmichthyiden by its scale ridge lying on the dorsal center line, which extended from the back of the head to the base of the dorsal fin, and by the larger number of dorsal scales (usually 22 to 36). The scales were sawn at their rear edge. A keel with saw-like scales also lay along the midline of the abdomen. The head was short and broad, the mouth pointed and more or less above. The supraoccipitalia (skull bones) formed a well-developed crest in Diplomystus . The dorsal fin, which was about the middle of the body, was small and pointed, the anal fin was elongated. The caudal fin was forked.
Systematics
The American paleontologist Edward Drinker Cope assigned Diplomystus to the herring (Clupeidae) in his first description . Today the genus is not considered a member of the herring-like (Clupeiformes), but is assigned to the Ellimmichthyformes, which is the sister group of the herring-like.
Valid species of the genus are:
- Diplomystus dentatus Cope, 1877, early Eocene Fossil Butte Member , type species and only Diplomystus species living in freshwater .
- Diplomystus birdi Woodward, 1895, Upper Cretaceous Lebanon.
- Diplomystus dubertreti Signeux, 1951. Upper Cretaceous Lebanon.
Diplomystus brevissimus (Blainville, 1818) was placed in the genus Armigatus , and Diplomystus longicostatus (Cope, 1886) became the type species of the genus Ellimmichthys . Other Diplomystus species have been synonymous with D. dentatus .
literature
- Karl Albert Frickhinger: Fossils Atlas Fish , Mergus-Verlag, Melle, 1999, ISBN 3-88244-018-X
- Lance Grande: A Revision of the Fossil Genus Diplomystus, With Comments on the Interrelationships of Clupeomorph Fishes American Museum Novitates, 1982, New York, No. 2728
Web links
- † Diplomystus Cope 1877 at the Paleobiology Database.