rudist
Quick Summary
Rudists were extinct bivalve mollusks that lived during the Cretaceous Period. They are characterized by having one valve that was elongated and conical, with a thick shell, and a smaller, cap-like valve that fit on top. These mollusks were significant marine builders, forming reef-like structures that were often dominant over corals in the Tethyan region. Rudist reef structures are now important sources of petroleum in certain regions. Rudists, along with ammonites and belemnites, became extinct at the end of the Cretaceous Period, an event possibly triggered by an asteroid impact.123
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Cretaceous PeriodCorrelationRudist, inoceramid, and exogyrid bivalves have been used in many areas to subdivide (zone) the Cretaceous Period for the purpose of correlation. Rudist bivalves, for example, have been employed in conjunction with larger foraminiferans to zone sediments of the Tethyan regions in parts of Europe.…
Read MoreRudist, inoceramid, and exogyrid bivalves have been used in many areas to subdivide (zone) the Cretaceous Period for the purpose of correlation. Rudist bivalves, for example, have been employed in conjunction with larger foraminiferans to zone sediments of the Tethyan regions in parts of Europe.…
Read More- Cretaceous PeriodMarine life
…based on the occurrence of rudist-dominated organic reeflike structures. Rudists were large, rather unusual bivalves that had one valve shaped like a cylindrical vase and another that resembled a flattened cap. The rudists were generally dominant over the corals as framework builders. They rarely existed outside the Tethyan region, and…
Read More…based on the occurrence of rudist-dominated organic reeflike structures. Rudists were large, rather unusual bivalves that had one valve shaped like a cylindrical vase and another that resembled a flattened cap. The rudists were generally dominant over the corals as framework builders. They rarely existed outside the Tethyan region, and…
Read More - Cretaceous PeriodMass extinction
Rudist bivalves disappeared, as did bivalves with a reclining life habit, such as Exogyra and Gryphaea. The stratigraphically important inoceramids also died out. Overall, approximately 80 percent of animal species disappeared, making this one of the largest mass extinctions in Earth’s history.
Read MoreRudist bivalves disappeared, as did bivalves with a reclining life habit, such as Exogyra and Gryphaea. The stratigraphically important inoceramids also died out. Overall, approximately 80 percent of animal species disappeared, making this one of the largest mass extinctions in Earth’s history.
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