Ammonites
(AM mun ites)
Specimen location: Varies
Like squid and octopus, ammonites belong to the class Cephalopoda, meaning "feet-on-head." The head and arms of the ammonites extended from their chambered and typically coiled shells. Ammonites first appeared nearly 225 million years ago; the last species died along with the dinosaur extinction approximately 65 million years ago.
Bacultes sp.
Ammonites were usually tightly coiled. A few species had loose coils and others were more irregular. A very few types such as Baculites, were straight except fo the very end.
When all of the external shell surface is removied, an intricate suture pattern can be seen, as in this specimen. The ammonite occupied only the outermost chamber at any one time.
Rhaebocera halli
All ammonites have internally compartmentalized shells, as seen here. The body of
Dunveganoce
Many ammonites have strong ribbing. In some species, the ribs even have short spines.
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