Amminits

Amminits are a diverse and extinct group of cephalopods that lived from the Devonian period to the end of the Cretaceous period. They are characterized by their coiled, chambered shells. These shells, known as ammonitic shells, were typically planispiral, meaning they coiled in a single plane, although some variations existed. The chambers within the shell were separated by walls called septa, and a tube called a siphuncle ran through these chambers, allowing the ammonite to control its buoyancy.

Amminits were abundant and widespread in ancient oceans, inhabiting a variety of marine environments. Their shells often contained intricate suture patterns where the septa met the outer shell wall, which are important features used by paleontologists for classification and identification. The size of ammonite shells varied greatly, from less than a centimeter to over two meters in diameter.

As predators, ammonites likely fed on smaller marine organisms such as plankton, crustaceans, and other invertebrates. Their coiled shells provided protection from predators, and their ability to control buoyancy likely aided in their movement and hunting strategies. The extinction of ammonites at the end of the Cretaceous period is often linked to the mass extinction event that also wiped out the non-avian dinosaurs. Their fossilized shells are common and have been found on every continent, offering valuable insights into past marine ecosystems and the evolution of life on Earth.