Smithsonian National Museum of Natural History Geologic Time The Story of a Changing Earth
Presented by the Department of Paleobiology.
The Ordovician
Contents
Eon Overview
Reef Ecosystems and the Paleozoic Fauna
New Animals as Biostratigraphic Tools
Ordovician Climate and Plate Tectonics
Evidence
Ordovician trilobite
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sample
Starfish
references and links
Foundational Concepts
Dating Methods
Earth Processes
Life Processes
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Ordovician Climate and Plate Tectonics
During the Ordovician, tectonic activity occurred in New England and the British Isles as North America moved toward the equator and began to collide with Europe. This led to mountain-building along these major plate margins. As plates continued to shift in position, diverse faunas were brought into contact with one another. Plate movement may also have contributed to the formation of the first Paleozoic ice age, as the southern continent of Gondwana moved over the South Pole. Glaciers began to form in what is now the Sahara region of Africa. This climate change was possibly associated with the mass extinction at the end of the Ordovician. These tectonic clues allow scientists to make sense out of geologic patterns in the Earth, and to map present-day continents and islands onto these old deposits.

The Ordovician world was dominated by diverse marine environments, mostly populated by a wide variety of invertebrate animals. Nearly all the major animal groups were evolving rapidly in the Ordovician, developing into many new species. Terrestrial plants were still rare so the land was probably a relatively barren desert. In fact, there is evidence for continental glaciation on Gondwana (North Africa and elsewhere). As a result, the globe was divided between mostly warm, shallow, tropical and subtropical marine zones and cold, barren terrestrial regions.




Overview | Reef Ecosystems and the Paleozoic Fauna | New Animals as Biostratigraphic Tools
Ordovician Climate and Plate Tectonics



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