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Regions of the suture line and variants in suture patterns Ammonite clean cut While nearly all nautiloids show gently curving sutures, the ammonoid suture line (the intersection of the septum with the outer shell) is variably folded, forming saddles ("peaks" that point towards the aperture) and lobes ("valleys" which point away from the aperture).
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.
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
W. A. Cobban and Hook, S. C. 1983 Mid-Cretaceous (Turonian) ammonite fauna from Fence Lake area of west-central New Mexico. Memoir 41, New Mexico Bureau of Mines&Mineral Resources, Socorro NM. W. A. Cobban and Hook, S. C. 1979, Collignoniceras woollgari wooollgari (Mantell) ammonite fauna from Upper Cretaceous of Western Interior, United States.
Of the few genera of ammonites which are thought to have survived the K-Pg extinction event into the Danian period (65-61 Myr) of the Paleogene, Hoploscaphites is the most widely and reliably recorded, with finds in Denmark, the Netherlands and the United States, and a possible record in Turkmenistan.
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. [ 1 ]
Perisphinctes is an extinct genus of ammonite cephalopod. They lived during the Middle to Late Jurassic epochs and serve as an index fossil for that time period. [5] The species P. boweni was named after the English chemist and geologist E. J. Bowen (1898–1980). [6]