Authentic unpolished fossilized Goniatite, 2.6 cm diameter, 400 million years old, Devonian, Morocco

Description

Goniatites are an extinct group of marine cephalopods related to ammonites that form the order Goniatitida. Goniatites appeared during the Middle Devonian, about 400 million years ago, and became extinct at the end of the Permian, about 250 million years ago.

All goniatites possessed an external shell divided internally into gas-filled chambers, giving the animal the ability to float in water. An open chamber at the front of the shell provided a living space for the goniatite, with access to water through a ventral opening. The morphology and lifestyle of goniatites were probably similar to those of their later relatives, the ammonites, being able to swim freely in the ocean and having a head with two eyes and well-developed arms (or tentacles).

The typical goniatite has a specific suture on the shell that gives it the name “goniatite.” A distinctive “zigzag” pattern is present in some of the sutures.

Goniatites are found in North America, Europe, North Africa and Australasia where they are used as index fossils in age determination and stratigraphic correlation. Notable accumulations of goniatites are found in certain limestones in the west of Ireland (notably Slieve Anierin), which are full of beautifully preserved goniatite fossils. They are also found in the marine Carboniferous coal beds of Europe and in the Pennsylvanian marine rocks of Arkansas. Large numbers of goniatites are also found in the Devonian rocks of Morocco.