Definition of eurypterid in English:



  • A giant fossil marine arthropod of a group occurring in the Palaeozoic era. They are related to horseshoe crabs, and resemble large scorpions with a terminal pair of paddle-shaped swimming appendages.

    Subclass Eurypterida, class Merostomata, subphylum Chelicerata

    • ‘Important fossil groups are the trilobites, a large group of Palaeozoic marine arthropods of uncertain affinity, and the eurypterids, Palaeozoic marine forms related to the arachnids.’
    • ‘Dr Selden said the Megarachne, a giant eurypterid or sea scorpion, is closely related to a creature called Woodwardopterus, from the Carboniferous Period, found in Scotland and with relatives in South Africa.’
    • ‘The most remarkable example is the three-dimensionally preserved soft tissues of the giant conodont animal Promissum pulchrum, eurypterids and other arthropods from the Upper Ordovician Soom Shale of South Africa.’
    • ‘Similarly, with the dramatic decline of marine eurypterids (large arthropods) about 410 million years ago, the first large marine predators were lost.’
    • ‘Miller said he also hopes to study the relationship, if any, between Doliodus problematicus and giant, ancient sea scorpions, a type of eurypterid related to horseshoe crabs.’


Late 19th century from modern Latin Eurypterus (genus name), from eury- + Greek pteron ‘wing’ + -id.