Description
- Freshwater Bony Fish in natural matrix
- Species: Knightia alta
- Age: Eocene, 50 Million Years Old
- Source: Wyoming Green River Formation, USA
- Size: 75-100mm fish
- Image shows exact item received.
Fish fossils from the USA are some of the most valuable and diverse fossils in the world, and are incredibly important to palaeontologists and evolutionary biologists. They span an extensive range of geological periods, from the Devonian, through the Cretaceous, and into the Eocene epoch; allowing an almost complete history of fish biology and evolution to be established. Many of these fish fossils have been found in the Green River Formation; one of the most famous fossil sites in the world, located in Wyoming, Colorado, and Utah. The Green River Formation is a geologic formation that records the cycle of sedimentation in a series of mountain lakes in three different basins. Although most of the fossils collected from the Green River Formation (GRF) are fishes, many other animals have been found including crocodilians, lizards, snakes, birds, bats, horses, amphibians, gastropods, crustaceans, and insects.
This fish fossil is of a Knightia species, Knightia is an extinct genus of bony fish that lived in the freshwater lakes and rivers of North America and Asia during the Eocene, 56 to 33.9 million years ago. These small fish belong to the same taxonomic family as herring and sardines, and resembled the them closely enough that both Knightia alta and Knightia eocaena were originally described as species of true herring in the genus Clupea. It is believed Knightia fed on algae and diatoms, as well as insects and occasionally smaller fish, a diet similar to their modern day cousins. Knightia fish had heavy scales, and small conical teeth. Rows of dorsal and ventral scutes ran from the back of the head to the medial fins. Often fossils of these animals are found in close proximity, even on top of one another, leading palaeontologists to believe these were a shoaling fish that lived in large groups.
