eurypterid vs arthropod

eurypterid and arthropod both are nouns.

Word	Noun	Adjective	Verb	Adverb
eurypterid	Yes	No	No	No
arthropod	Yes	No	No	No

As nouns, arthropod is a hypernym of eurypterid; that is, arthropod is a word with a broader meaning than eurypterid:

eurypterid: large extinct scorpion-like arthropod considered related to horseshoe crabs
arthropod: invertebrate having jointed limbs and a segmented body with an exoskeleton made of chitin

eurypterid (noun)	arthropod (noun)
large extinct scorpion-like arthropod considered related to horseshoe crabs	invertebrate having jointed limbs and a segmented body with an exoskeleton made of chitin