| Group: | Actinopterygii (Fish) |
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| Specimen Number: | |
| Age: | Early Eocene |
| Where Found: | Green River Formation, Wyoming, USA. |
| Date Found: | 1877 |
| Size: | |
| Original Material: | |
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| Type: | Large Plaque |
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An extinct ray-finned fish related to modern herrings and anchovies. Diplomystus is found worldwide in lower Eocene formations, but is particularly abundant in the famous Green River Formation in Wyoming. Specimen length is generally between 10cm and 20cm, although some samples are known to exceed 50cm. The distinctive upturned mouth is indicative of a surface feeder, and indeed, Diplomystus digestive tracts often contain preserved genera of such biotopes.
Diplomystus serves as the basis for any Eocene collection, and provides rich evolutionary data for phylogenetic, ecological, or morphological studies.
Cope, ED. (1877). A Contribution to the Knowledge of the Ichthyological Fauna of the Green River Shales. Bulletin of the US Geological and Geographical Survey, Vol. 3, Art XXXIV, pp 807-819.
Chang, M, and Maisey, JG. (2003). Redescription of Ellimma branneri and Diplomystus shengliensis, and Relationships of Some Basal Clupeomorphs. American Museum Novitates, No. 3404, pp. 1-35.
Grande, L. (1982). A Revision of the Fossil Genus Diplomystus, With Comments on the Interrelationships of Clupeomorph Fishes. American Museum Novitates, No. 2728, pp. 1-34.
Wilson, MVH. (1981). Eocene Freshwater Fishes from the Coalmont Formation, Colorado. Journal of Paleontology, Vol. 55, No. 3, pp. 671-674.