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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).
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
These ammonites lived in the Jurassic from Sinemurian to Toarcian [2] (age range: 196.5 to 182.0 million years ago). Fossils of this genus can be found in Argentina, Austria, Canada, Chile, China, France, Germany, Hungary, Italy, Morocco, Portugal, Slovakia, Spain, Tunisia, Turkey and United States.
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.
Their shells had ornate ribs whose function is unknown, although some scientists have speculated that these ribs helped strengthen the animals' shells to allow them to live at greater depths where the water pressure is higher.
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 ...
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.
[3] [4] The fossils come in two sizes, the macroconch (female) ranging in size from 95 to 175 millimetres (3.7 to 6.9 in) in diameter and the microconch (male) which ranges from 24 to 41 millimetres (0.94 to 1.61 in). When the animal was alive, the interior of the shell was divided into chambers which were partly filled with air for buoyancy.