Ammonitoidea

1 definition found

From The Collaborative International Dictionary of English v.0.48 [gcide]:

  Ammonitoidea \Am*mon`i*toid"e*a\, n. pl. [NL., fr. Ammonite +
     -oid.] (Zool.)
     An extensive group of fossil cephalopods often very abundant
     in Mesozoic rocks. See {Ammonite}.
     [1913 Webster]