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Ammonoids are extinct spiral shelled cephalopods comprising the subclass Ammonoidea. They are more closely related to living coleoids (i.e., octopuses , squid and cuttlefish ) than they are to shelled nautiloids (such as the living Nautilus ). [ 1 ]
Parapuzosia seppenradensis is the largest known species of ammonite. [1] It lived during the Lower Campanian Epoch of the Late Cretaceous period, in marine environments in what is now Westphalia, Germany.
This list of ammonites is a comprehensive listing of genera that are included in the subclass †Ammonoidea, excluding purely vernacular terms. The list includes genera that are commonly accepted as valid, as well as those that may be invalid or doubtful ( nomina dubia ), or were not formally published ( nomina nuda ), as well as junior ...
Agoniatitida, also known as the Anarcestida, is the ancestral order within the cephalopod subclass Ammonoidea originating from bactritoid nautiloids, that lived in what would become Africa, Asia, Australia, Europe, and North America during the Devonian from about the lower boundary of Zlichovian stage (corresponding to late Pragian, after 409.1 mya) into Taghanic event during upper middle ...
They come in various forms, including evolute shells where all whorls are exposed, and strongly involute shells with only the outer whorl visible. Shells may be heavily ribbed, with some featuring nodes and spines, while others are completely smooth. Some shells have broad, rounded venters (the outer rim), while others have a sharp, keel-like ...
Acanthodiscus is found in shallow water sediments in both the Tethyan and Boreal realms where it is used as an index fossil.In fact, the International Commission on Stratigraphy (ICS) has assigned the First Appearance Datum of Acanthodiscus radiatus, the first species of the genus, as the defining biological marker for the start of the Hauterivian stage of the Cretaceous, ~132.9 million years ago.
The shell forms a loose open helical spiral in the early stages, ending in one or two straight shafts in the mature adult. Surface ornament consists of prominent rounded nodes on the lower and upper flanks, connected by strong looped ribs. The nodes may have been the bases of long sharp spines.
Parapuzosia is an extinct genus of desmoceratid ammonites from the Cenomanian to the Campanian of Africa, Europe, and North America. [2] They are typically very large ammonites, reaching diameters of 60 cm (2.0 ft) or more, with the largest species measuring around 2 m (6.6 ft). [3]