Ammonitoidea
Pronunciation : Am*mon`i*toid"e*a
Part of Speech : n. pl.
Etymology : [NL., fr. Ammonite + -oid.] (Zo?l.)
Definition : Defn: An extensive group of fossil cephalopods often very abundant in Mesozoic rocks. See Ammonite.
Source : Webster's Unabridged Dictionary, 1913