Ammonoidea can be divided into six orders:
Agoniatitida: Lower Devonian - Middle Devonian
Clymeniida: Upper Devonian
Goniatitida: Middle Devonian - Upper Permian
Prolecanitida: Upper Devonian - Upper Triassic
Ceratitida: Upper Permian - Upper Triassic
Ammonitida: Lower Jurassic - Upper Cretaceous
If they are geometric with numerous undivided lobes and saddles and eight lobes around the conch, we refer to their pattern as goniatitic, a characteristic of Paleozoic ammonites. Like other cephalopods, ammonites had sharp, beak-like jaws inside a ring of squid-like tentacles that extended from their shells. They used these tentacles to snare prey — plankton, vegetation, fish and crustaceans — similar to the way a squid or octopus hunt today. Ammonites were skilled and successful hunters. They caught their prey while swimming and floating in the water column. This cluster of ammonites cemented together in death would have hunted our ancient seas as keen predators.