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Solenochilus
''Solenochilus'', type genus of the Solenochilidae is an extinct cosmopotilian nautilid from the Lower Pennsylvanian to the Lower Permian with a rapidly expanding, coiled globular shell with few whorls, from which prominent spines extend laterally from the umbilical area at maturity. ''Solenochilus'' is derived from the Upper Mississippian '' Acanthonautilus'', principally through evolutionary changes in the siphuncle. The siphuncle in both ''Solenochilus'' and ''Acanthonautilus'' is ventral, running just inside the outer rim of the shell. In both the siphuncle is mostly composed of thin connecting rings. The siphuncle in ''Solenochilus'' is wider and has a more sinuous profile than that of ''Acanthonautilus''. Both swing dorsally between septa, but more so in ''Solenochilus''. In both the septal necks are somewhat long and straight on the ventral side but in ''Solenochilus'' they are cyrtochoanitic and recumbent on the dorsal side, rather than simply curved back, cyrtochoanitic ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Acanthonautilus
''Acanthonautilus'' is an extinct genus in the nautilid family Solenochildae (Aipocerataceae) from the Upper Mississippian of North America and equivalent (uL Carb) strata in Europe, first described by Foord in 1896. ''Acanthonautilus'', like ''Solenochilus'', has an involute, globular shell of few volutions that enlargens with fair rapidity, with prominent lateral spines extending from the umbilical area at maturity. The siphuncle in ''Acanthonautilus'' is narrower than in ''Solenochilu''s and not as sinuous. As with ''Solenochilus'', septal necks on the outer, or ventral, side are straight, but those on the inner, or dosal, side rather than being recumbent are simply curved, cyrtochoanitic. Most of the siphuncle is thin connecting ring which from the outside is slightly ventrally concave and slightly dorsally convex between septa. ''Acanthonautilus'' may have been derived from ''Aipoceras'', or possibly ''Asymptoceras'' and give rise, principally through modification of the s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Solenochilidae
Solenochilidae is a small family of Carboniferous and Early Permian nautilids, similar and related to the Aipoceratidae The Aipoceratidae are a small family of Carboniferous nautilids which have smooth shells and loosely coiled to faintly impressed whorls and in which the aperture may be modified at maturity. The Aipoceratidae include the Lower Carboniferous ''A ... that comprises genera with whorls in contact and which develop laterally projecting umbilical spines by maturity. The included genera '' Solenochilus'' and '' Acanthonautilus'' are quite similar in external form but differ in their siphuncles. Those of ''Solenochilus'' have more strongly inflated siphuncle segments and more tightly curved septal necks. References * Bernhard Kummel, 1964. Nautiloidea - Nautilida; Treatise on Invertebrate Paleontology, Part K. Geological Society of America and University of Kansas Press. Prehistoric nautiloid families Mississippian first appearances Cisuralian extinctions [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Permonautilus
''Permonautilus'' is an extinct genus of nautilids from the Upper Permian of Russia, named and described by Kruglov in 1933. ''Permonautilus'' is an involute, globular, spinose member of the Lirocertidae which are included in the Clydonautilaceae. Whorl sections are broad, with a rounded venter. The umbilicus in the middle of the shell is deep, from which spine-like processes extend laterally in the mature portion near the aperture. The siphuncle in ''Permonautilus'' is subcentral, the suture, slightly sinuous. Externally, ''Permonautilus'' closely resembles the Pennsylvanian - Lower Permian ''Solenochilus'' and the Upper Mississippian ''Acanthonautilus'', both which belong to the superfamily Aipocerataceae: ''Permonautilus'' differs from the latter two genera in the anatomy of the subcentral siphuncle. See also * Nautiloid ** List of nautiloids References * , B. 1964;Nautiloidea—Nautilida, in the Treatise on Invertebrate Paleontology The ''Treatise on Invertebra ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pennsylvanian (geology)
The Pennsylvanian ( , also known as Upper Carboniferous or Late Carboniferous) is, in the International Commission on Stratigraphy, ICS geologic timescale, the younger of two period (geology), subperiods (or upper of two system (stratigraphy), subsystems) of the Carboniferous Period. It lasted from roughly . As with most other geochronology, geochronologic units, the stratum, rock beds that define the Pennsylvanian are well identified, but the exact date of the start and end are uncertain by a few hundred thousand years. The Pennsylvanian is named after the U.S. state of Pennsylvania, where the coal-productive beds of this age are widespread. The division between Pennsylvanian and Mississippian (geology), Mississippian comes from North American stratigraphy. In North America, where the early Carboniferous beds are primarily marine limestones, the Pennsylvanian was in the past treated as a full-fledged geologic period between the Mississippian and the Permian. In parts of Europe, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Permian
The Permian ( ) is a geologic period and stratigraphic system which spans 47 million years from the end of the Carboniferous Period million years ago (Mya), to the beginning of the Triassic Period 251.9 Mya. It is the last period of the Paleozoic Era; the following Triassic Period belongs to the Mesozoic Era. The concept of the Permian was introduced in 1841 by geologist Sir Roderick Murchison, who named it after the region of Perm in Russia. The Permian witnessed the diversification of the two groups of amniotes, the synapsids and the sauropsids ( reptiles). The world at the time was dominated by the supercontinent Pangaea, which had formed due to the collision of Euramerica and Gondwana during the Carboniferous. Pangaea was surrounded by the superocean Panthalassa. The Carboniferous rainforest collapse left behind vast regions of desert within the continental interior. Amniotes, which could better cope with these drier conditions, rose to dominance in place of their am ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nautilida
The Nautilida constitute a large and diverse order of generally coiled nautiloid cephalopods that began in the mid Paleozoic and continues to the present with a single family, the Nautilidae which includes two genera, ''Nautilus'' and ''Allonautilus'', with six species. All told, between 22 and 34 families and 165 to 184 genera have been recognised, making this the largest order of the subclass Nautiloidea. Classification and phylogeny Current classification The current classification of the Nautilida, in prevalent use, is that of Bernhard Kummel (Kummel 1964) in the Treatise which divides the Nautilida into five superfamilies, the Aipocerataceae, Clydonautilaceae, Tainocerataceae, and Trigonocerataceae, mostly of the Paleozoic, and the later Nautilaceae. These include 22 families and some 165 or so genera (Teichert and Moore 1964) Other concepts Shimansky 1962 (in Kummel 1964) divided the Nautilida into five suborders, the mostly Paleozoic Centroceratina, Liroceratina, Rutoc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Siphuncle
The siphuncle is a strand of tissue passing longitudinally through the shell of a cephalopod mollusk. Only cephalopods with chambered shells have siphuncles, such as the extinct ammonites and belemnites, and the living nautiluses, cuttlefish, and ''Spirula''. In the case of the cuttlefish, the siphuncle is indistinct and connects all the small chambers of that animal's highly modified shell; in the other cephalopods it is thread-like and passes through small openings in the septa (walls) dividing the camerae (chambers). Some older studies have used the term siphon for the siphuncle, though this naming convention is uncommon in modern studies to prevent confusion with a mollusc organ of the same name. Function The siphuncle is used primarily in emptying water from new chambers as the shell grows. To perform this task, the cephalopod increases the saltiness of the blood in the siphuncle, and the water moves from the more dilute chamber into the blood through osmosis. At the sam ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Treatise On Invertebrate Paleontology
The ''Treatise on Invertebrate Paleontology'' (or ''TIP'') published by the Geological Society of America and the University of Kansas Press, is a definitive multi-authored work of some 50 volumes, written by more than 300 paleontologists, and covering every phylum, class, order, family, and genus of fossil and extant (still living) invertebrate animals. The prehistoric invertebrates are described as to their taxonomy, morphology, paleoecology, stratigraphic and paleogeographic range. However, taxa with no fossil record whatsoever have just a very brief listing. Publication of the decades-long ''Treatise on Invertebrate Paleontology'' is a work-in-progress; and therefore it is not yet complete: For example, there is no volume yet published regarding the post-Paleozoic era caenogastropods (a molluscan group including the whelk and Common periwinkle, periwinkle). Furthermore, every so often, previously published volumes of the ''Treatise'' are revised. Evolution of the proje ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nautiloids
Nautiloids are a group of marine cephalopods (Mollusca) which originated in the Late Cambrian and are represented today by the living ''Nautilus'' and ''Allonautilus''. Fossil nautiloids are diverse and speciose, with over 2,500 recorded species. They flourished during the early Paleozoic era, when they constituted the main predatory animals. Early in their evolution, nautiloids developed an extraordinary diversity of shell shapes, including coiled morphologies and giant straight-shelled forms ( orthocones). Only a handful of rare coiled species, the nautiluses, survive to the present day. In a broad sense, "nautiloid" refers to a major cephalopod subclass or collection of subclasses (Nautiloidea ''sensu lato''). 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 rela ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pennsylvanian First Appearances
Pennsylvanian may refer to: * A person or thing from Pennsylvania * Pennsylvanian (geology), a geological subperiod of the Carboniferous Period * Pennsylvanian (train), ''Pennsylvanian'' (train), an Amtrak train {{disambiguation ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
