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The Ordovician - The oldest group of fish the ostracodemrs...

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The Ordovician The Ordovician plant record consists solely of spored with a trilete mark, a y-shaped feature formed when the spores were formed by (presumably) meiosis. One possible interpretation of the presence of spores is that the land plant (trilete) spore have evolved prior to the move of plant ancestral types onto land. The vertebrates evolved during the Cambrian period, possibly from a creature similar to the Burgess Shale animal Pikaia or an organism similar to the "conodont" animal.
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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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