Fossil Record of Cephalopod1

Fossil Record of Cephalopod1 - fossils The first of these...

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Fossil Record of Cephalopods During much of their evolutionary history cephalopods possessed a hard shell. Their abundance, the presence of a shell, and the environments they lived in led to an excellen fossil record for the group. The Ordovician period saw the exolution and spread of coiled, swimming cephalopods. This group, the nautiloids (shown in Figure 10), resembles somewhat their living distant relatives the chambered nautilus and squids. During the Devonian period Cephalopods ammonoid group known as the goniatites appeared. These coiled, chambered nautiloids, some of which are shown in Figure 11, left a great many fossils, some of which are quite aesthetically appealing.
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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
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Unformatted text preview: 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 . Differences between the groups are shown in Figure 12. The cephalopods recovered from the extinction of the goniatites at the close of the Paleozoic era and developed a remarkably similar group, the ceratites. These coiled, chambered animals, such as the one shown in Figure 12, had slightly more complex sutures than did the goniatites. However, the Ceratites also went extinct during the middle Mesozoic era....
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This note was uploaded on 11/29/2011 for the course BIO BSC1010 taught by Professor Gwenhauner during the Fall '10 term at Broward College.

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Fossil Record of Cephalopod1 - fossils The first of these...

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