| Clonograptus | |
|---|---|
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| Graptolites, like this Amplexograptus from the Ordovician near Caney Springs, Tennessee are good zone fossils. A zone fossil must have a short time span but a common animal of the time. Graptolites became extinct at the end of the Devonian. | |
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| Genus: | Clonograptus |
Clonograptus is a genus of graptolites. Groups of these animals were connected by stalklike structures to a central region. Species of Clonograptus are zone fossils, and can be used to find the precise age of Ordovician rocks. [1]
