Description
Fossil Fish knightia, Eocene period 40- 50 million years ago
This Fossil fish is an excellent example and the actual fish measures 10cm in length. The details are very well preserved and is a very well defined example. The typical adult size of the Knightia fish range from 7cm to 12 cm with very few larger specimens.
Knightia were a species of freshwater fish resembling the herring that lived in large shoals 40-50 million years ago. This fossil comes from the Green River Formation, in South West Wyoming, USA. This area was once one vast lake with an abundance of food which meant that the fish thrived. Their diet was largely consisting of plankton, algae and also ostracods, tiny flea size shrimps. Likewise the Knightia themselves would have been an important part of the diet of larger fish, birds and turtles. Some years, maybe due to fluctuating temperatures, many fish died with sediment quickly covering them. This is now a world famous area for fossil fish, knightia being the species most that frequently occurs.
The Green River Formation is a very fossiliferous area along three distinct basins following the course of the Green River. However the name of the actual lake that produces the knightia fossil fish is the aptly named ‘Fossil Lake’. The mud and sediment here had very fine grains which helped preserve these delicate fossils. The various fossil beds span a period of 5 million years and produce a variety of other fossils. Larger fish such as the Diplomystus and Asterotrygon a freshwater stingray are more infrequent discoveries. Other fossils include the Borealosuchus crocodile, bats and a strange armadillo like mammal the Brachianodon westorum.
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