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The resulting spontaneous concentric precipitation of minerals around a fossil, a concretion, is responsible for the outstanding preservation of many ammonite fossils. When ammonites are found in clays , their original mother-of-pearl coating is often preserved.
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 ...
Ammonites franconicus Schlotheim, 1813 Pleuroceras spinatum is a species of ammonite from the lower Jurassic , upper Pliensbachian period (189.6 ± 1.5 – 183.0 ± 1.5 Mya). Species of this genus were fast-moving nektonic carnivore.
Douvilleiceras is a genus of ammonites from the Middle to Late Cretaceous. Its fossils have been found worldwide, in Africa , Asia , Europe , and North and South America . Description
An aptychus is a type of marine fossil. It is a hard anatomical structure, a sort of curved shelly plate, now understood to be part of the body of an ammonite. Paired aptychi have, on rare occasions, been found at or within the aperture of ammonite shells. The aptychus was usually composed of calcite, whereas the ammonite shell was aragonite.
Dactylioceras has been collected from almost every continent, and was one of the most successful ammonite lineages ever.They are abundant throughout Europe, with exceptionally fine specimens found in England and Germany.
Ammolite comes from the fossil shells of the Upper Cretaceous disk-shaped ammonites Placenticeras meeki and Placenticeras intercalare, and (to a lesser degree) the cylindrical baculite, Baculites compressus. Ammonites were cephalopods, that thrived in tropical seas until becoming extinct along with the dinosaurs at the end of the Mesozoic era.
Mortoniceras is an ammonoid genus belonging to the superfamily Acanthocerataceae, named by Meek in 1876, based on Ammonites vespertinu, named by Morton in 1834. Mortoniceras is the type genus of the Mortoniceratinae, one of 4 subfamilies in the Brancoceratidae which is part of the Acanthocerataceae (renamed Acanthoceratoidea to conform with the ...