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Ammonoids are also known as ammonites, and are related to living coleoids such as octopuses and squid. They have distinctive septa, sutures and siphuncles, and are used as index fossils for geologic time periods.
Ammonites were ancient marine predators with coiled shells that lived from 416 to 66 million years ago. Learn about their appearance, behavior, evolution, and extinction, and how they are used as index fossils today.
Ammonites were ocean-dwelling molluscs that died out 66 million years ago. Learn about their shells, evolution, extinction and how to identify their species from fossils.
Mar 17, 2021 · Ammonite facts, pictures and information. Ammonites are prehistoric marine mollusks with distinctive curled shells. Once abundant in Earth’s oceans, ammonites – along with the dinosaurs and many other species – became extinct during the Cretaceous-Paleogene Extinction Event that occurred around 66 million years ago.
Ammonites were extinct marine animals with coiled shells similar to nautilus. They are used as guide fossils for stratigraphy and have a worldwide distribution and evolutionary history.
Ammonoids, commonly known as Ammonites, were sea creatures that belonged to the class Cephalopoda. They possessed an outside shell that was coil-like, with the nautilus of today being its most direct counterpart. Approximately 450 million years ago, the Ammonoidea subclass—often known as Ammonites—first emerged.
Aug 6, 2024 · Ammonoid, any of a group of extinct cephalopods (of the phylum Mollusca), forms related to the modern pearly nautilus (Nautilus), that are frequently found as fossils in marine rocks dating from the Devonian Period (began 419 million years ago) to the Cretaceous Period (ended 66 million years ago).
