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Ammonites. Smithsonian Institution Press. ISBN 978-1-58834-024-5. Walker, Cyril and Ward, David. Fossils. Dorling, Kindersley Limited, London, 2002. A Broad Brush History of the Cephalopoda by Dr. Neale Monks, from The Cephalopod Page. Ammonite maturity, pathology and old age By Dr. Neale Monks, from The Cephalopod Page. Essay about the life ...
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.
Shell of Pleuroceras spinatum can reach a diameter of about 45–54 millimetres (1.8–2.1 in).These ammonites have a planulate shell with a quadrate whorl section, bearing strong radial ribs ending in ventro-lateral tubercles. The venter is tabulate with a strong serrated keel.
Dactylioceras was a widespread genus of ammonites from the Lower Jurassic period, [1] approximately 180 million years ago . [2] and Like many other ammonites, the genus Dactylioceras is extremely important in biostratigraphy, being a key index fossil for identifying their region of the Jurassic. It had a nearly cosmopolitan distribution during ...
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
Lewesiceras is a genus of large ammonites belonging to the order Ammonitida and the family Pachydiscidae. They lived in the late Cretaceous period, in the Cenomanian and Turonian ages, which occurred 99.6-89.3 million years ago. These shelled ammonoids were nektonic, fast-moving and carnivorous.
These ammonites have a strongly ribbed shell and ammonitic suture. Early whorls are coronate, which later become round, then oval in section. Primary ribs may have swellings (bullae) at the umbilicus or are without. In early stages primary ribs branch mid flank at prominent lateral tubercles.
Fossils (Smithsonian Handbooks) by David Ward; Cephalopods Present and Past: New Insights and Fresh Perspectives by Neil H. Landman, Richard Arnold Davis, and Royal H. Mapes; Ammonoid Paleobiology (Topics in Geobiology) by Neil H. Landman, Kazushige Tanabe, and Richard Arnold Davis; Guide to Fossils (Firefly Pocket series) by Firefly Books