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Ammonites in the permanent collection of The Children's Museum of Indianapolis. At least 57 species of ammonites, which were widespread and belonged to six superfamilies, were extant during the last 500,000 years of the Cretaceous, indicating that ammonites remained highly diverse until the very end of their existence.
Ammonites of prehistoric North America — a marine molluscs group of the prehistoric Cephalopods in North America. Subcategories This category has the following 5 subcategories, out of 5 total.
Although almost all evidence indicated that ammonites did not survive past the K–Pg boundary, there is some scattered evidence that some ammonites lived for a short period of time during the Paleocene epoch, although none survived the Danian (66-61 Ma); [1] they were likely extinct within 500,000 years of the K-Pg extinction event, which ...
Ammonitida or "True ammonites" are an order of ammonoid cephalopods that lived from the Jurassic through Paleocene time periods, commonly with intricate ammonitic sutures. Ammonitida is divided into four suborders, the Phylloceratina , Lytoceratina , Ancyloceratina , and Ammonitina .
Pages in category "Early Jurassic ammonites of North America" The following 6 pages are in this category, out of 6 total. This list may not reflect recent changes. E.
Fossils have been found throughout North America from localities in South Carolina, [1] North Carolina, [2] South Dakota, [3] Maryland, [4] New Jersey [5] and Mexico. [6] There is also evidence of the genus being present from the island of Trinidad , although the material found from here cannot be classified at the species level. [ 7 ]
Oxynoticeras is an extinct genus of ammonite from the Early Jurassic [1] of Europe and North America. [2] This genus is characterized by its smooth shell, with almost invisible undulations on the flank, and a sharp keel. [3] Synonym Oxynotoceras was created by Buckman as misspelling. [4]
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.