The ammonites are a diverse subclass of widespread cephalopod mollusks from the Early Devonian-Late Cretaceous of the entire world. They, as a whole, were named in 1884 by Karl Alfred von Zittel. They were another group of successful animals (swimming in the oceans for about 334 million years), and are more closely related to squid and octopi than they are to the nautiloids.
Physiology[]
Ammonites were unique mollusks. Many of them had a curly shell, and, although it is unknown how long their arms were, it can be assumed that they were long enough to capture food; as well as this, their eyes may have been as large as those of squid and octopi, and they may have had a small, keratinous beak hiding between their circular row of arms. Their bodies would have been covered in smooth skin, and mostly covered by their hard shells.
Diet[]
Ammonites were carnivores, either living as predators or suspension feeders. Predatory ammonites likely had long, hooked arms used for getting a hold of struggling prey, as well as a keratinous, scissor-like beak for crushing them and tearing them to pieces.
Ammonite genera (note that those are not all the ones that exist)[]
Goniatites[]
Goniatites is a goniatitid goniatitid ammonite from the Early Devonian-Late Triassic of Czech Republic, Spain, the United States of America, Germany, Ireland, Morocco, the United Kingdom, and Italy. It was officially named in 1825 by Wilhelm de Haan. It would have swam in inland seas, as opposed to the open ocean preference of other ammonites. It was a predator, feeding on small invertebrates.
Asteroceras[]
Asteroceras is an arietitid ammonitid ammonite from the Late Triassic-Early Jurassic of the United States of America, Canada, China, Germany, Hong Kong, Hungary, Turkey, and the United Kingdom. It was named in 1815 by James Sowerby. It was a truly big ammonite, and had the generic ammonite lifestyle, swimming around in open oceans. It was a predator, feeding on small invertebrates.
Perisphinctes[]
Perisphinctes is a perisphinctid ammonitid ammonite from the Middle-Late Jurassic of the entire world. It was named in 1869 by Wilhelm Heinrich Waagen. It lived the generic ammonite lifestyle, and often serves as an index fossil for the Jurassic. It was a predator, feeding on small invertebrates.
Baculites[]
Baculites is a baculitid ammonitid ammonite from the Late Cretaceous of the entire world. It was named in 1801 by Jean-Baptiste Lamarck. It was a unique ammonite, as its shell was somewhat straightened out, somewhere between the completely straight shells of Paleozoic nautiloids such as Orthoceras, Cameroceras, and Endoceras, and the completely curled shells of other ammonites. It was a planktivore, sucking up colonies of plankton drifting through the water.
Parapuzosia[]
Parapuzosia is a desmoceratid ammonitid ammonite from the Late Cretaceous of France, Germany, Spain, the United States of America, and Cuba. It was officially named in 1913 by Ronald M. Nowak. It was the biggest ammonite to exist; however, it still would have been prey to predators such as Tylosaurus. It was a predator, feeding on small invertebrates.
In popular culture[]
Due to documentaries and books focusing on prehistoric animals, ammonites have become the most popular prehistoric mollusks to have ever existed. Since then, they have been featured in major pieces of media like Fantasia and Dinosaur Revolution; in these pieces of media, they are often depicted as squid-like predators with long tentacles. So far, their biggest public appearance was in the first episode of the 1999 documentary, Walking with Dinosaurs, where the widespread ammonite genus, Perisphinctes, was shown as a common animal in Jurassic Britain, living alongside the many marine reptiles that swam the seas (and had sometimes tried to eat it).