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Paratornoceratinae
Paratornoceratinae is a subfamily of oxyconic dimeroceratids included in the order Goniatitida, a group of Paleozoic ammonoids, which have closer affinity to living coleoids than to '' Nautilus''. Paratornoceratinae as defined by Ebbighausen, Becker, & Bockwinkel in 2002 comprises three recognised genera with sharp, oxyconic, venters; ''Acrimeroceras ''Acrimeroceras'' is an oxyconic Devonian goniatite and one of three genera included in the subfamily Paratornoceratinae. The others being '' Paratornoceras'' and ''Paratoceras'' or ''ex'' '' Polonites''. ''Acrimeroceras'' has a shell like ...'', '' Paratornoceras'', and '' Polonites''. The shell, as described for the type, ''Paratornoceras'', is subglobular and evolute on young stages, but discoidal and with closed umbilicus in the adult. References * Ebbighausen, V., Becker, R.T. & Bockwinkel, J. (2002): Morphometric Analyses and Taxonomy of oxyconic Goniatites (Paratornoceratinae n. subfam.)... Proceedings of the Geo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Acrimeroceras
''Acrimeroceras'' is an oxyconic Devonian goniatite and one of three genera included in the subfamily Paratornoceratinae. The others being '' Paratornoceras'' and ''Paratoceras'' or ''ex'' '' Polonites''. ''Acrimeroceras'' has a shell like that of ''Paratornoceras'' with biconvex growth lines and constrictions and simple dorsal lobe. The adult shell is extremely compressed, smooth, oxyconic to lanceolate in section. Early growth stages are depressed, subglobular, smooth or ribbed, with an open umbilicus and rounded to suboxyconic venter, which sharpens relatively early during ontogeny. Sutural elements in general are broadly rounded except for the lateral lobe which is pointed and asymmetric. References * Morphometric Analyses and Taxonomy of Oxyconic Goniatites (Paratornoceratinae n. subfam) from the Early Famennean Tafilalt of the (Anti-Atlas, Morocco) in Proceedings of the Geological Survey, 57, Vienna, 2002. * ''Acrimeroceras'' iGoniat TaxonomyAcrimeroceras- Paleodb* Mi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dimeroceratidae
Dimeroceratidae is one of three families in the Dimeroceratoidea, a goniatid superfamily included in the Ammonoidea; extinct shelled cephalopods with adorally convex septa and usually narrow ventro-marginal siphuncles. The family Dimeroceratidae was established for the genus '' Dimeroceras'' which was previously included in the Cheiloceratidae in the Treatise on Invertebrate Paleontology Part L, but differing from the similar subglublar to thickly lenticular ''Cheiloceras ''Cheiloceras'' is a subglobular to thickly lenticular goniatite with a closed umbilicus from the Upper Devonian and type genus for the Cheiloceratidae. ''Cheiloceras'' is sometimes split into at least three subgenera. ''Cheiloceras (Cheilocer ...'' in having a large lateral lobe and the umbilical lobe outside the umbilicus. The Dimeroceratidae are derived from the Cheiloceratid genus '' Torleyoceras'' through the ancestral '' Paradimeroceras'' which gave rise to ''Dimeroceras'', (Saunders et al. 1999). ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Devonian
The Devonian ( ) is a geologic period and system of the Paleozoic era, spanning 60.3 million years from the end of the Silurian, million years ago (Mya), to the beginning of the Carboniferous, Mya. It is named after Devon, England, where rocks from this period were first studied. The first significant adaptive radiation of life on dry land occurred during the Devonian. Free-sporing vascular plants began to spread across dry land, forming extensive forests which covered the continents. By the middle of the Devonian, several groups of plants had evolved leaves and true roots, and by the end of the period the first seed-bearing plants appeared. The arthropod groups of myriapods, arachnids and hexapods also became well-established early in this period, after starting their expansion to land at least from the Ordovician period. Fish reached substantial diversity during this time, leading the Devonian to often be dubbed the Age of Fishes. The placoderms began dominating ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Genus
Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus comes above species and below family (taxonomy), family. In binomial nomenclature, the genus name forms the first part of the binomial species name for each species within the genus. :E.g. ''Panthera leo'' (lion) and ''Panthera onca'' (jaguar) are two species within the genus ''Panthera''. ''Panthera'' is a genus within the family Felidae. The composition of a genus is determined by taxonomy (biology), taxonomists. The standards for genus classification are not strictly codified, so different authorities often produce different classifications for genera. There are some general practices used, however, including the idea that a newly defined genus should fulfill these three criteria to be descriptively useful: # monophyly – all descendants ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Goniatitida
Goniatids, informally goniatites, are Ammonoidea, ammonoid cephalopods that form the order Goniatitida, derived from the more primitive Agoniatitida during the Middle Devonian some 390 million years ago (around Eifelian stage). Goniatites (goniatitids) survived the Late Devonian extinction to flourish during the Carboniferous and Permian only to become Permian–Triassic extinction event, extinct at the end of the Permian some 139 million years later. Morphology All goniatites possessed an external shell, which is divided internally into chambers filled with gas giving it buoyancy during the life of the animal. An open chamber at the front of the shell provided living space for the goniatitid animal, with access to open water through a ventral siphuncle. The general morphology and habit of goniatites was probably similar to that of their later relatives the Ammonitida, ammonites, being free swimming and possessing a head with two well developed eyes and arms (or tentacles). G ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ammonoidea
Ammonoids are a group of extinct marine mollusc animals in the subclass Ammonoidea of the class Cephalopoda. These molluscs, commonly referred to as ammonites, are more closely related to living coleoids (i.e., octopuses, squid and cuttlefish) than they are to shelled nautiloids such as the living ''Nautilus'' species. The earliest ammonites appeared during the Devonian, with the last species vanishing during the Cretaceous–Paleogene extinction event. Ammonites are excellent index fossils, and linking the rock layer in which a particular species or genus is found to specific geologic time periods is often possible. Their fossil shells usually take the form of planispirals, although some helically spiraled and nonspiraled forms (known as heteromorphs) have been found. The name "ammonite", from which the scientific term is derived, was inspired by the spiral shape of their fossilized shells, which somewhat resemble tightly coiled rams' horns. Pliny the Elder ( 79 AD nea ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Coleoidea
Subclass (biology), Subclass Coleoidea, or Dibranchiata, is the grouping of cephalopods containing all the various taxa popularly thought of as "soft-bodied" or "shell-less" (i.e., octopuses, squid and cuttlefish). Unlike its extant sister group, Nautiloidea, whose members have a rigid outer shell for protection, the coleoids have at most an internal cuttlebone, gladius (cephalopod), gladius, or shell that is used for buoyancy or support. Some species have lost their cuttlebone altogether, while in some it has been replaced by a chitinous support structure. A unique trait of the group is the ability to edit their own RNA. The major divisions of Coleoidea are based upon the number of cephalopod limb, arms or tentacles and their structure. The extinct and most primitive form, the Belemnoidea, presumably had ten equally-sized arms in five pairs numbered Dorsum (biology), dorsal to ventral as I, II, III, IV and V. More modern species either modified or lost a pair of arms. The superor ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nautilus
The nautilus (, ) is a pelagic marine mollusc of the cephalopod family Nautilidae. The nautilus is the sole extant family of the superfamily Nautilaceae and of its smaller but near equal suborder, Nautilina. It comprises six living species in two genera, the type of which is the genus ''Nautilus''. Though it more specifically refers to species ''Nautilus pompilius'', the name chambered nautilus is also used for any of the Nautilidae. All are protected under CITES Appendix II. Depending on species, adult shell diameter is between 4 and 10 inches. Nautilidae, both extant and extinct, are characterized by involute or more or less convolute shells that are generally smooth, with compressed or depressed whorl sections, straight to sinuous sutures, and a tubular, generally central siphuncle.Kümmel, B. 1964. Nautiloidae-Nautilida, in the Treatise on Invertebrate Paleontology, Geological Society of America and Univ of Kansas Press, Teichert and Moore eds. Having survived relatively u ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Devonian First Appearances
The Devonian ( ) is a period (geology), geologic period and system of the Paleozoic era, spanning 60.3 million years from the end of the Silurian, million years ago (Mya), to the beginning of the Carboniferous, Mya. It is named after Devon, England, where rocks from this period were first studied. The first significant adaptive radiation of life on dry land occurred during the Devonian. Pteridophyte, Free-sporing vascular plants began to spread across dry land, forming extensive forests which covered the continents. By the middle of the Devonian, several groups of plants had evolved leaves and true roots, and by the end of the period the Pteridospermatophyta, first seed-bearing plants appeared. The arthropod groups of myriapods, arachnids and Hexapoda, hexapods also became well-established early in this period, after starting their expansion to land at least from the Ordovician period. Fish reached substantial diversity during this time, leading the Devonian to often be ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
