Search results
Results From The WOW.Com Content Network
Iridescent ancient ammonite fossil on display at the American Museum of Natural History, New York City, around 2 feet in diameter. The Ammonoidea can be divided into six orders, listed here starting with the most primitive and going to the more derived: Agoniatitida, Lower Devonian – Middle Devonian; Clymeniida, Upper Devonian
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 ...
Ceratitidae is an extinct family of ammonite cephalopods. Fossils of Ceratitidae are found in the Triassic marine strata throughout the world, including Asia, Europe, the Middle East, North America, and Oceania.
Ammonites with evolute, serpenticone to cadicone shells with ribs, sometimes with tubercules. Members of this family had no keels. while homeomorphic with stephanoceratids and perisphinctids, they had unique shell structure with double shells and flat-topped ribs on the inner shell. Based on suture differences, they are divided into 2 subfamilies.
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 .
Ammonitina comprises a diverse suborder of ammonite cephalopods that lived during the Jurassic and Cretaceous periods of the Mesozoic Era. They are excellent index fossils, and it is often possible to link the rock layer in which they are found to specific geological time periods.
Acanthoceras fossils have been found in Australia, Brazil, Bulgaria, Colombia (Hondita Formation, Prado, Tolima), [2] Denmark, Egypt, Marocco, France, Germany, India ...
Asteroceras stellare, the true star ammonite, is an extinct species of cephalopod belonging to the Ammonite subclass and to the family Arietitidae. [ 1 ] These fast-moving nektonic carnivores lived during the lower Jurassic period, around 196.5 to 189.6 million years ago.