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The Devonian - known as the goniatites These coiled...

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The Devonian The Devonian period (410 to 360 million years ago) saw a continued diversifiaction of life on the land, including the first terrestrial vertebrates , the amphibians , and the first forests of trees. In the waters fish continued their diversification with the rise of the lobe-finned and ray-finned fish. Invertebrates such as crinoids, coral, and brachiopods thrived in shallow seas during the Devonian. Invertebrates Brachiopods continued their diversification in the Devonian seas. One important group, the spiriferids, produced shells with elongated hinges, as seen in the image below. The Devonian marked the time of greatest brachiopod diversity, approximately 200 genera have been described.
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Cephalopods also underwent an increase in forms, notably the ammonoid group
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Unformatted text preview: known as the goniatites. These coiled, chambered nautiloids left a great many fossils, some of which are quite aesthetically appealing. The ammonoids underwent three separate diversifications from a nautiloid-like stock. In each case the fold pattern of sutures became more complex. These sutire patterns are fantastic characters for identifying species, making ammonoids excellent index fossils. The first of these occurrences was the goniatites, a group that ranged from the Devonian to the Permian. The ceratites are a Triassic group, while the last group, the ammonites ranged from the Triassic to the Cretaceous . Ammonoids finally went extinct in the great end-of-the- Cretaceous extinction. Nautiloids are represented today by the Nautilus ....
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