ammonite

(redirected from Ammonitida)
Also found in: Dictionary, Thesaurus, Encyclopedia, Wikipedia.

ammonite

(ăm′ə-nīt′)
n.
1. An extinct cephalopod mollusk of the order Ammonitida of the Permian to Cretaceous Periods, having a thick, usually coiled shell characterized by intricate suture patterns where the septa between individual chambers join the outer shell wall.
2. An ammonoid.

am′mo·nit′ic (-nĭt′ĭk) adj.

ammonite

a name given to a large group of fossil cephalopod molluscs of late Palaeozoic and Mesozoic time that possessed a spiral shell very similar to that of Nautilus.