eurypterid
/jʊəˈrɪptərɪd/noun
1- 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.板足鲎（指一种巨大的海洋化石节肢动物）。
1.1
- Subclass Eurypterida, class Merostomata, subphylum Chelicerata.板足鲎亚纲, 肢口纲, 有螯肢亚门动物。
词源
late 19th cent.: from modern Latin Eurypterus (genus name), from EURY-+ Greek pteron 'wing'+-ID2 .