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Solitary Rugose Coral (Un-named)
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This beautiful specimen of a solitary rugose coral was found in the Ordovician Arthur Marble formation in a roadside section in the Cobb Valley, north-west of Nelson. Rugose corals are an extinct order of both solitary and colonial corals, that were especially abundant during the late Palaeozoic. Solitary species, like the one shown here, are sometimes known as horn corals, because the chamber is typically horn-shaped in cross-section (see the depictions at the centre of the drawing by Ernst Haeckel right). They were benthic species, living on the floor of relatively shallow lime-rich seas.
In horn corals each horn (or corallite) comprises a central column (the columella) supporting a set of radiating septa (seen above). The arrangement of these septa varies by species, so helps in identification. This structure provided physical support to the coral - something that was not needed in colonial corals, because each corallite was supported by its neighbours. |
Rugose Corals drawn by Ernst Haeckel Kunstformen der Natur (1904), plate 29
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