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Paraloxoceras
''Paraloxoceras'' is a genus of straight shelled, orthoconic nautiloid cephalopods, now extinct, that lived during the Early Carboniferous. Fossils have been found in Europe and central Asia; the type, ''P. konincki'', named by Flower, came from Belgium. The shell of ''Paraloxoceras'' is slightly depressed, with straight sutures. Septa are fairly close spaced. The siphuncle is located about halfway between the center and the venter with segments that are broadly expanded into the chambers. As typical for the subfamily, ''Paraloxoceras'' contains organic endosiphuncular deposits penetrated by a canal system similar to that found in actinocerids but differs in the having a protoconch characteristic of the pseudorthocerids. During grow of the animal the shell expands dorsally with the distance between the dorsum and siphuncle increasing while the separation between the venter and siphuncle remains at a more or less constant. Related genera include ''Pseudactinoceras'', ''Macro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
List Of Nautiloids
This list of nautiloids is a comprehensive listing of all genera that have ever been included in the subclass Nautiloidea, excluding purely vernacular terms. The list includes all commonly accepted genera, but also genera that are now considered invalid, doubtful (''nomina dubia''), or were not formally published (''nomina nuda''), as well as junior synonyms of more established names, and genera that are no longer considered nautiloids. Most of the listed genera are found in Part K of the ''Treatise on Invertebrate Paleontology''. Some, added since the year of publication (1964) are found simply in various scientific journals and special publications. The named genera are based on type specimens which are housed in various museums and other academic institutions worldwide, available to interested researchers. Note that ''Allonautilus'' and ''Nautilus'' are the only extant genera. A *†'' Acanthonautilus'' *†'' Acaroceras'' *†''Acleistoceras'' *†'' Acrosphaerorthoceras'' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Carboniferous
The Carboniferous ( ) is a geologic period and system of the Paleozoic that spans 60 million years from the end of the Devonian Period million years ago ( Mya), to the beginning of the Permian Period, million years ago. The name ''Carboniferous'' means "coal-bearing", from the Latin '' carbō'' ("coal") and '' ferō'' ("bear, carry"), and refers to the many coal beds formed globally during that time. The first of the modern 'system' names, it was coined by geologists William Conybeare and William Phillips in 1822, based on a study of the British rock succession. The Carboniferous is often treated in North America as two geological periods, the earlier Mississippian and the later Pennsylvanian. Terrestrial animal life was well established by the Carboniferous Period. Tetrapods (four limbed vertebrates), which had originated from lobe-finned fish during the preceding Devonian, became pentadactylous in and diversified during the Carboniferous, including early amphibian line ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Animal
Animals are multicellular, eukaryotic organisms in the Kingdom (biology), biological kingdom Animalia. With few exceptions, animals Heterotroph, consume organic material, Cellular respiration#Aerobic respiration, breathe oxygen, are Motility, able to move, can Sexual reproduction, reproduce sexually, and go through an ontogenetic stage in which their body consists of a hollow sphere of Cell (biology), cells, the blastula, during Embryogenesis, embryonic development. Over 1.5 million Extant taxon, living animal species have been Species description, described—of which around 1 million are Insecta, insects—but it has been estimated there are over 7 million animal species in total. Animals range in length from to . They have Ecology, complex interactions with each other and their environments, forming intricate food webs. The scientific study of animals is known as zoology. Most living animal species are in Bilateria, a clade whose members have a Symmetry in biology#Bilate ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mollusc
Mollusca is the second-largest phylum of invertebrate animals after the Arthropoda, the members of which are known as molluscs or mollusks (). Around 85,000 extant species of molluscs are recognized. The number of fossil species is estimated between 60,000 and 100,000 additional species. The proportion of undescribed species is very high. Many taxa remain poorly studied. Molluscs are the largest marine phylum, comprising about 23% of all the named marine organisms. Numerous molluscs also live in freshwater and terrestrial habitats. They are highly diverse, not just in size and anatomical structure, but also in behaviour and habitat. The phylum is typically divided into 7 or 8 taxonomic classes, of which two are entirely extinct. Cephalopod molluscs, such as squid, cuttlefish, and octopuses, are among the most neurologically advanced of all invertebrates—and either the giant squid or the colossal squid is the largest known invertebrate species. The gastropods ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cephalopod
A cephalopod is any member of the molluscan class Cephalopoda (Greek plural , ; "head-feet") such as a squid, octopus, cuttlefish, or nautilus. These exclusively marine animals are characterized by bilateral body symmetry, a prominent head, and a set of arms or tentacles (muscular hydrostats) modified from the primitive molluscan foot. Fishers sometimes call cephalopods "inkfish", referring to their common ability to squirt ink. The study of cephalopods is a branch of malacology known as teuthology. Cephalopods became dominant during the Ordovician period, represented by primitive nautiloids. The class now contains two, only distantly related, extant subclasses: Coleoidea, which includes octopuses, squid, and cuttlefish; and Nautiloidea, represented by ''Nautilus'' and ''Allonautilus''. In the Coleoidea, the molluscan shell has been internalized or is absent, whereas in the Nautiloidea, the external shell remains. About 800 living species of cephalopods have been ident ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nautiloid
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 rel ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pseudorthocerida
Pseudorthocerida is an order of generally straight longiconic orthoceratoids with a subcentral to marginal cyrtochoanitic siphuncle composed of variably expanded segments which may contain internal deposits that may develop into a continuous parietal lining. (Sweet 1964). Cameral deposits are common and concentrated ventrally. Apices typically have a slight to moderate exogastric curvature The Pseudorthocerida are included in a broad in-group of generally orthoconic cephalopods known as the Orthoceratoidea (Kroger 2008) along with the Ascocerida, Dissidocerida, Lituitida, and Orthocerida. The Pseudorthocerida were among the last living orthoconic nautiloids. One family, the Trematoceratidae, survived into the Triassic Period. Taxonomy Current understanding By current understanding the Pseudorthocerida contains the following families. :Pseudorthoceratidae : Cayutoceratidae :Pseudactinoceratidae :Spyroceratidae :Carbactinoceratidae : Trematoceratidae The Pseudorthocer ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pseudactinoceratidae
Pseudactinoceraidae is a family in the cephalopod order Pseudorthocerida, known from the Upper Devonian and Lower Carboniferous ( Mississippian).Nautiloidea-Orthocerida by Walter C Sweet, Treatise on Invertebrate Paleontology Part K Mollusca 3, R.C Moore (ed) 1964 Pseuactinocerids are characterized by elongated, straight and gently curved shells with a subcentral 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 ... composed of broadly expanded segments in the adult in which there are internal deposits pieced by two series of radial canals. Deposits form initially at the septal openings and grow mostly forward to connect with the next deposit in the anterior part of the next segment. The radial canals connect the interior of the segments with the ends of the connecting rings ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nautiloid
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 rel ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Septum (mollusc Anatomy)
Septa (singular septum) are thin walls or partitions between the internal chambers ( camerae) of the shell of a cephalopod, namely nautiloids or ammonoids. As the creature grows, its body moves forward in the shell to a new living chamber, secreting septa behind it. This adds new chambers to the shell, which can be clearly seen in cross-sections of the shell of the living nautilus, or in ammonoid and nautiloid fossils. The septa are attached to the inside wall of the shell, thus dividing the phragmocone into camerae. Where the septum meets the shell a suture line forms; in some ammonoids these lines became extremely complex and elaborate, providing strength without the necessity of added weight. Elaborate sutures allowed for thinner shells, and hence less time needed for shell growth and less time spent in the vulnerable juvenile stage. The nature and structure of the septa, as with the camerae, and siphuncle, and the presence or absence of deposits, are important in cl ... [...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] |
Actinocerida
The Actinocerida are an order of generally straight, medium to large cephalopods that lived during the early and middle Paleozoic, distinguished by a siphuncle composed of expanded segments that extend into the adjacent chambers, in which deposits formed within contain a system of radial canals and a narrow space along the inner side of the connecting ring known as a paraspatium. (Teichert 1964) Septal necks are generally short and cyrtochoanitic, some being recumbent, some hook shaped. Most grew to lengths of about but some, like the Huroniidae of the Silurian grew significantly larger. Ecology The Actinocerida inhabited shallow to quite deep waters, where they alternated between swimming and lying on the bottom. They were predatory, and able to control their buoyancy to a greater degree than their contemporaries. Derivation The derivation of the Actinocerida remains enigmatic. They first appear late in the Early Ordovician (Cassinian Stage, late Floian) with the Georginida ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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