Unformatted text preview: The oldest group of fish, the ostracodemrs, first appeared during the Cambrian, before their extinction at the close of the devonian. The Ordovician. was a time of great transgression of the seas onto the continents, producing a great many habitats in which new forms of life, such as fish, could develop. The exact appearance of the Ordovician fish in unclear. What we do have is fragments of hard coverings of soft tissue....
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- Fall '10
- Biology, Cambrian, Burgess Shale, Ordovician plant record