Ostracods

Cytherelloidea circumscripta, Lower Jurassic Source: BGR

Ostracods are small crustaceans with double-flapped shells of calcium carbonate and chitin in the scale of 0.2 - 30 millimeters. Due to their double-flapped structure, they are also known as ostracods. In their growth development they go through up to 8 molting stages. Ostracods are found in all aquatic habitats such as puddles, rivers, lakes and oceans. In the oceans they colonize all water depths, from the tidal influenced shallow water to the deep sea.

Ostracods have been handed down since the Cambrian and since then have provided valuable guide fossils of the earth's history. About 33,000 recent and fossil species are bibliographically described. Ostracods are very diverse and highly specialized. For this reason, ostracod societies react sensitively to changing environmental conditions and are recently used in environmental monitoring. They are also of great importance for palaeoenvironmental analysis due to the occurrence of different species in certain sea basin and freshwater areas and the resulting facies areas.

Application areas of ostracods in BGR und LBEG

Ostracods represent a very important fossil group in the biostratigraphical classification of rocks of the Mesozoic in Lower Saxony. With the aid of the ostracods, for example, the very thick but often lithologically monotonous claystone sequence of the Lower Jurassic and the Lower Cretaceous can be subdivided biostratigraphically.

Literature

Luppold, F. W. & Weiss, W. (1997): Geologische Stadtkarte Hannover 1 : 25 000, Karte A: Festgestein und Erläuterungen. – [in] Rohde, P. & Becker-Platen, J. D. (1997): Geologische Stadtkarte Hannover 1 : 25 000, Karte A Festgestein, Karte B Grundwasser, Karte C Geotechnik: 154 Seiten, 37 Abbildungen, 5 Tabellen, 3 Karte, Hannover.

Luppold, F. W., Rohde, P. & Weiss, W. (2001)[2003]: Karte der Festgesteinsverbreitung 1 : 50 000 und neue Gliederung der Kreide-Schichten durch Mikrofossilien – besonders Ostrakoden – im Gebiet Hannover. – Bericht Naturhistorische Gesellschaft Hannover, 143: 27-97, 8 Abbildungen, 4 Tabellen, 10 Tafaln, 1 Karte., Hannover.