ammonitler

Ammonites are an extinct group of marine molluscs belonging to the subclass Ammonoidea, which falls within the phylum Mollusca. They are closely related to modern cephalopods, such as squid, octopus, and nautilus. Ammonites were characterized by their distinctive coiled shells, which typically took the form of a flat spiral, though some species exhibited more complex coiling patterns, including uncoiled or irregularly coiled shells. These shells were chambered, with the animal inhabiting only the outermost chamber. The internal chambers were filled with gas or liquid, allowing the ammonite to control its buoyancy in the water column.

Fossils of ammonites are abundant in marine sedimentary rocks dating from the Devonian period (around 400 million years ago) to the end of the Cretaceous period (around 66 million years ago). Their widespread distribution and rapid evolution made them valuable index fossils for geologists, helping to date rock layers. Ammonites varied greatly in size, from less than a centimeter to over two meters in diameter. They were predators, likely feeding on small invertebrates and fish. The diversity of ammonite forms and their relatively short geological lifespan make them a rich subject for paleontological study, offering insights into ancient marine ecosystems and evolutionary processes. Their extinction, along with that of the dinosaurs, marks a significant event in Earth's history.