Fossil Record of Bivalves

Fossil Record of Bivalves - Mesozoic. These bivalves,...

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Fossil Record of Bivalves Since they have hard shells, the fossil record of this class is remarkably good. Hard shells (or hard parts) are one of the features that make an organism a better candidate to become a fossil. Gastropods, another class of the phylum Mollusca, also become more prevalent in the Ordovician seas. Ordovician deposits yield snails, as well as large, sedentary gastropods such as Maclurites, shown in Figure 6. During the Mesozoic era, bivalves became more abundant and important parts of reefs. They would would remain important parts of the marine fauna throughout the
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Unformatted text preview: Mesozoic. These bivalves, specifically the rudistids (Figure 7), began to play a larger role in reef formation. Rudistid reefs are so named because the rudistid bivalves were the dominant reef-forming organisms. Biodiversity was reduced by mass extinctions at the end of the Triassic and Jurassic periods of the mesozoic era. . The bivalves recovered from the Jurassic extinctions and again became major reef-formers in the numerous shallow marginal seas that encroached onto the continents during the Cretaceous, as shown by Figure 8....
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Fossil Record of Bivalves - Mesozoic. These bivalves,...

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