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Words related to ordovician

Or·do·vi·cian
O o

  • chain coral

    coral of the extinct genus Halysites, from the Ordovician and Silurian periods, consisting of oval, laterally compressed corallites united to form a chainlike structure.

  • graptolite

    any colonial animal of the extinct class Graptolithina, most common in the Ordovician and Silurian Periods, thought to be related to the pterobranchs.

  • nautiloid

    a mollusk of the subclass Nautiloidea, including nautiluses and many fossil species that were abundant in the Ordovician and Silurian periods.

  • ostracoderm

    any of several extinct jawless fishes of the Ordovician, Silurian, and Devonian periods, having the body enclosed in an armor of bony plates.
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