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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.
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.
The line where each septum meets the outer shell is called the suture or suture line. Like other true ammonites, Baculites have intricate suture patterns on their shells that can be used to identify different species. A fossil cast of the shell of a Baculites grandis on display at the North American Museum of Ancient Life in Lehi, Utah.
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
Fossil evidence supports this general idea since swarms of hatchling ammonitellae fossils are known although there are no associated egg fossils. [2] One of the eggs preserved in the Kimmeridge Clay ammonite egg cluster K1486 bears crystalline phosphate on its surface. Since phosphate is mobile only in organic form this suggests the eggs were ...
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.