A fossil cephalopod shell related to the nautilus. There are many genera and species, and all are extinct, the typical forms having existed only in the Mesozoic age, when they were exceedingly numerous. They differ from the nautili in having the margins of the septa very much lobed or plaited, and the siphuncle dorsal. Also called serpent stone, snake stone, and cornu Ammonis.
Ammonites had a spiral shell similar to the closely related Nautilus. They are also related to squid and octopus. Their name comes from the Egyptian god Ammon (Amun) who is sometimes associated with ram horns similar in shape to ammonites. They appeared around 400 million years ago and evolved very quickly, making them useful for dating rocks. Ammonites became extinct at the same time as the dinosaurs, 65 million years ago.
Sea faring creatures from the Cretaceous period, ammonites were mollusks that built a chambered shell in which they would pump air into the empty chambers which allowed them to float at different levels of the ocean.
a marine organism with a coiled hard shell, that lived from the Lower Devonian and were extinct by the end of the Cretaceous Period.
one of the coiled chambered fossil shells of extinct mollusks
a fossil cephalopod with a curled shell that has the form of the horns on Greek representations of Zeus-Ammon
An extinct type of shelled cephalopod. It has a multi-chambered, generally coiled shell. The chambers of ammonites are separated by complexly corrugated partitions called septa.
In general usage, this is the common name for all the Ammonoidea (see below). As used by palaeontologists, however, this name is used to describe only the most highly evolved members of the Ammonoidea, namely the Phylloceratina, Lytoceratina, Ammonitina, and Ancyloceratina. The more primitive Ammonoidea are instead referred to as goniatites or ceratites.
Fossil of a (usually spiraled) Cephalopod which lived through the Cretaceous period.
The flat, spiral, or coiled fossil shell of an extinct mollusk of the cephalopod group: ammonites are related to the living nautilus.
A type of extinct cephalopod mollusk that had a shell marked with sutures. Especially common in the seas of the Mesozoic Era.
A coiled, chambered fossil shell of a cephalopod mollusk of the extinct order Ammonoidea.
Ammonite - Any ammonoid cephalopod belonging to the order Ammonitida, characterized by a thick, ornamented shell with sutures (seams) having finely divided lobes and saddles. Range: Jurassic to Cretaceous.
An extinct sea creature similar to a snail’s shell. It was one of the very first kinds of life.
Ammonite was an early mollusk, a fast-moving predatory marine invertebrate.
an extinct mollusk that is related to squid and octopus but has a chambered and often spiraled shell. The word ammonite is derived from Ammon, an Egyptian god who took the form of a ram. Ammonites are similar in appearance to a ram's horn.
A Mesozoic cephalopod with flat, spiral shells [LCOTE
Probably the most commonly associated fossil in the world. Ammonite's are an extinct group of marine 'cephalopod molluscs' that thrived during the Jurassic and Cretaceous period (170 - 65 million years ago). Ammonites consisted of a coiled shell within which the creature lived. These agile predators preyed on smaller marine creatures, including fish and shells. The closest living descendent of Ammonite's are Cuttle fish. To learn more about Ammonites click here.
Ammonites are an extinct group of marine animals of the subclass Ammonoidea in the class Cephalopoda, phylum Mollusca. They are excellent index fossils, and it is often possible to link the rock layer in which they are found to specific geological time periods. Ammonites' closest living relative is probably not the modern Nautilus (which they outwardly resemble), but rather the subclass Coleoidea (octopus, squid, and cuttlefish).
