Ammonoids: Fossils of Ancient Coiled Cephalopods
Ammonoids are extinct, coiled-shelled cephalopods that belong to the subclass Ammonoidea. Closely related to modern octopuses, squid, and cuttlefish, ammonoids are part of a diverse group that dominated the oceans for millions of years. They first appeared during the Emsian stage of the Early Devonian period and lasted until the Cretaceous–Paleogene extinction event, around 66 million years ago.
Ammonoids, often referred to as ammonites (particularly those from the Ammonitida order), were known for their remarkable diversity, with over 10,000 species described. They are excellent index fossils, helping geologists link rock layers to specific time periods. Their fossilized shells typically form planispirals, although some species also exhibited helically spiraled or non-spiraled forms, known as heteromorphs, especially during the Cretaceous period.
The name "ammonite" is derived from the spiral shape of their shells, which resemble the tightly coiled horns of a ram. The ancient Roman author Pliny the Elder referred to them as "ammonis cornua" (horns of Ammon) due to their resemblance to the horns of the Egyptian god Ammon, often depicted with ram’s horns.
Our collection of ammonoid fossils offers a unique glimpse into the ancient world. Whether you’re a collector, a geology enthusiast, or simply fascinated by these ancient creatures, these fossils make a stunning addition to any collection.