3-449: Kosmoceratidae is an extinct ammonite family from the Callovian (Middle Jurassic) to Early Cretaceous . Kosmoceratidae are probably the most polymorphic groups of Jurassic ammonites. These ammonoids have a more or less tabulate venter, with lateral or ventrolateral tubercles. The aptychus is double valved with a concentrically ribbed surface. This Ammonitina -related article
6-506: Is a stub . You can help Misplaced Pages by expanding it . Ammonitida 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 . The Phylloceratina
9-815: Is the ancestral stock, derived from the Ceratitida near the end of the Triassic . The Phylloceratina gave rise to the Lytoceratina near the beginning of the Jurassic which in turn gave rise to the highly specialized Ancyloceratina near the end of the Jurassic. Both the Phylloceratina and Lytoceratina gave rise to various stocks combined in the Ammonitina. These four suborders are further divided into different stocks, comprising various families combined into superfamilies. Some like
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