Ammonoidea - Wikipedia Ammonoids are excellent index fossils, and they have been frequently used to link rock layers in which a particular species or genus is found to specific geologic time periods
Ammonoid | Mesozoic, Extinct, Shell | Britannica 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)
2. 3 Ammonoidea - Digital Atlas of Ancient Life Ammonoidea, or ammonoids, constitute one of the most important clades of extinct invertebrate animals Their lovely shells have long made them favorites of collectors and their fossils have been known since ancient times
What is an ammonite? - Natural History Museum Ammonites were shelled cephalopods that died out about 66 million years ago Fossils of them are found all around the world, sometimes in very large concentrations The often tightly wound shells of ammonites may be a familiar sight, but how much do you know about the animals that once lived inside? What were ammonites?
Fossil Focus: Ammonoids – PALAEONTOLOGY [online] Ammonoids (Ammonoidea) are an extinct group of marine invertebrates with an external shell They were cephalopods, and hence closely related to modern cuttlefish, squid, octopuses and the pearly nautilus
Ammonoid - New World Encyclopedia The words "ammonoid" and "ammonite" are both commonly used to refer to any member of subclass Ammonoidea However, in stricter usage, the term "ammonite" is reserved for members of suborder (or order) Ammonitina
Suture Patterns within Subclass Ammonoidea | Natural History . . . All ammonoids show some type of suture pattern The term "suture pattern" refers to the featured line that makes contact with the septa and the interior of the aragonitic shell Ammonoid suture patterns show more complexity in comparison to the nautiloids whose sutures are comparatively simple