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A primary difference between ammonites and nautiloids is the siphuncle of ammonites (excepting Clymeniina) runs along the ventral periphery of the septa and camerae (i.e., the inner surface of the outer axis of the shell), while the siphuncle of nautiloids runs more or less through the center of the septa and camerae.
Nautiloids are typically considered one of three main groups of cephalopods, along with the extinct ammonoids (ammonites) and living coleoids (such as squid, octopus, and kin). While ammonoids and coleoids are monophyletic clades with exclusive ancestor-descendant relationships, this is not the case for nautiloids.
This list of ammonites is a comprehensive listing of genera that are included in the subclass †Ammonoidea, excluding purely vernacular terms. The list includes genera that are commonly accepted as valid, as well as those that may be invalid or doubtful ( nomina dubia ), or were not formally published ( nomina nuda ), as well as junior ...
This is a list of common chemical compounds with chemical formulae and CAS numbers, indexed by formula. This complements alternative listing at list of inorganic compounds . There is no complete list of chemical compounds since by nature the list would be infinite.
This glossary of chemistry terms is a list of terms and definitions relevant to chemistry, including chemical laws, diagrams and formulae, laboratory tools, glassware, and equipment. Chemistry is a physical science concerned with the composition, structure, and properties of matter , as well as the changes it undergoes during chemical reactions ...
Nautiloids were much more extensive and varied 200 million years ago. The ancestors of all Coleoidea (shell-less Cephalopods) once possessed shells, and many early cephalopod species are only known from shell remains. Following the K-Pg extinction event most nautiloid species went extinct, while members of Coleoidea managed to survive ...
Any shells with complex sutures were assigned to the genus Ammonites. This definition persisted for nearly 200 years, from the time of the genera's 1758 inception by Carl Linnaeus to 1949, when paleobiologist Arthur K. Miller provided a detailed description of the shell of N. pompilius, becoming the type species of the genus.
The chemical species can be an atom, molecule, ion, or radical, with a specific chemical name and chemical formula. [ 2 ] In supramolecular chemistry , chemical species are structures created by forming or breaking bonds between molecules, such as hydrogen bonding , dipole-dipole bonds , etc. [ 3 ] These types of bonds can determine the ...