ammonite
/ˈamənʌɪt
/noun
An ammonoid fossil, especially one of a later type found chiefly in the Jurassic and Cretaceous periods, typically with intricately frilled suture lines. Compare with ceratite and goniatite.
- Typified by ammonoids of the order Ammonitida.
- The fossil content consists of ammonites, belemnites, brachiopods, echinoderms, bivalves, crinoids, gastropods, ostracodes and benthic foraminifers.
- A feature of especial interest is that, while the youngest Triassic ammonites are quite rare, the oldest Jurassic ammonites are extremely abundant, entering the succession in a veritable flood.
Origin
Mid 18th century: from modern Latin ammonites, from medieval Latin cornu Ammonis 'horn of Ammon', from the fossil's resemblance to the ram's horn associated with Jupiter Ammon (see ammoniacal).