Ostracods
In: Méndez Dot, J.A.; Méndez Baamonde, J. (Ed.) (2026). Atlas of tropical carbonates: As exemplified by facies of Venezuela: past and present. Springer: Cham. ISBN 978-3-031-25493-2. XXVI, 515 pp. https://dx.doi.org/10.1007/978-3-031-25494-9, meer
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| Auteurs | | Top |
- Méndez Dot, J.A.
- Méndez Baamonde, J.
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| Abstract |
Ostracods (Phylum Arthropoda, Subphylum Crustacea) of the class Ostracoda are one of the best-documented groups within the animal kingdom. They have a well-documented fossil record from the Ordovician to the Present. This class is divided into two subclasses: Myodocopa and Podocopa. Members of the first are weakly calcified, exclusively nekto-planktonic and nekto-benthic swimming ostracods. Members of the subclass Podocopa (the focus of this chapter) secrete a well-calcified bivalve exoskeleton, known as a carapace, which is composed of low-Mg calcite and fossilizes easily. Podocopans consist of three extant orders, all first appearing in the Ordovician: Palaeocopida, Platycopida, and Podocopida. Palaeocopids, mainly confined to Paleozoic strata, are not common in modern settings. Platycopids are exclusively marine ostracods, moderately common in Mesozoic strata, and common in modern oceans. Members of the order Podocopida (inhabiting marine, fresh, and brackish water environments) are the most common, both in the fossil record and in modern oceans. Most ostracods are benthic heterotrophs that thrive mainly in the neritic zone. They are common components of heterozoan carbonates deposited during low-oxygen (but not anoxic) “kenoxic” events throughout the Phanerozoic. Therefore, the Heterozoan factory governs carbonate production in ostracod-rich deposits. Low Mg-calcite podocopan ostracod carapaces are widely used as geochemical proxies (e.g., δ18O with Mg/Ca and Sr/Ca ratios) for paleoenvironmental interpretations in sediments from the early Paleozoic to the Present. |
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