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Cladoselache
''Cladoselache'' is an extinct genus of shark-like chondrichthyan (cartilaginous fish) from the Late Devonian (Famennian) of North America. It was similar in body shape to modern lamnid sharks (such as mako sharks and the great white shark), but was not closely related to lamnids or to any other modern (selachian) shark. As an early chondrichthyan, it had yet to evolve traits of modern sharks such as accelerated tooth replacement, a loose jaw suspension, enameloid teeth, and possibly claspers. Some 20th century studies considered ''Cladoselache'' to be a basal (early-diverging) member of Elasmbobranchii, the fork of cartilaginous fish which leads to modern sharks and rays. More recent studies have identified distinctive traits of the chondrocranium (cartilaginous braincase), dorsal fin spines, and pectoral fin bases. These newly identified features support a close relationship to symmoriiforms, a small group of bizarre chondrichthyans such as the bristle-spined '' Stethacanthu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cladoselache
''Cladoselache'' is an extinct genus of shark-like chondrichthyan (cartilaginous fish) from the Late Devonian (Famennian) of North America. It was similar in body shape to modern lamnid sharks (such as mako sharks and the great white shark), but was not closely related to lamnids or to any other modern (selachian) shark. As an early chondrichthyan, it had yet to evolve traits of modern sharks such as accelerated tooth replacement, a loose jaw suspension, enameloid teeth, and possibly claspers. Some 20th century studies considered ''Cladoselache'' to be a basal (early-diverging) member of Elasmbobranchii, the fork of cartilaginous fish which leads to modern sharks and rays. More recent studies have identified distinctive traits of the chondrocranium (cartilaginous braincase), dorsal fin spines, and pectoral fin bases. These newly identified features support a close relationship to symmoriiforms, a small group of bizarre chondrichthyans such as the bristle-spined '' Stethacanthu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Selachian
Sharks are a group of elasmobranch fish characterized by a cartilaginous skeleton, five to seven gill slits on the sides of the head, and pectoral fins that are not fused to the head. Modern sharks are classified within the clade Selachimorpha (or Selachii) and are the sister group to the rays. However, the term "shark" has also been used to refer to all extinct members of Chondrichthyes with a shark-like morphology, such as hybodonts and xenacanths. The oldest modern sharks are known from the Early Jurassic. They range in size from the small dwarf lanternshark (''Etmopterus perryi''), a deep sea species that is only in length, to the whale shark (''Rhincodon typus''), the largest fish in the world, which reaches approximately in length. Sharks are found in all seas and are common to depths up to . They generally do not live in freshwater, although there are a few known exceptions, such as the bull shark and the river shark, which can be found in both seawater and fresh ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Shark
Sharks are a group of elasmobranch fish characterized by a cartilaginous skeleton, five to seven gill slits on the sides of the head, and pectoral fins that are not fused to the head. Modern sharks are classified within the clade Selachimorpha (or Selachii) and are the sister group to the rays. However, the term "shark" has also been used to refer to all extinct members of Chondrichthyes with a shark-like morphology, such as hybodonts and xenacanths. The oldest modern sharks are known from the Early Jurassic. They range in size from the small dwarf lanternshark (''Etmopterus perryi''), a deep sea species that is only in length, to the whale shark (''Rhincodon typus''), the largest fish in the world, which reaches approximately in length. Sharks are found in all seas and are common to depths up to . They generally do not live in freshwater, although there are a few known exceptions, such as the bull shark and the river shark, which can be found in both seawater and fresh ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chondrichthyan
Chondrichthyes (; ) is a class that contains the cartilaginous fishes that have skeletons primarily composed of cartilage. They can be contrasted with the Osteichthyes or ''bony fishes'', which have skeletons primarily composed of bone tissue. Chondrichthyes are jawed vertebrates with paired fins, paired nares, scales, and a heart with its chambers in series. Extant chondrichthyes range in size from the 10 cm (3.9 in) finless sleeper ray to the 10 m (32 ft) whale shark. The class is divided into two subclasses: Elasmobranchii (sharks, rays, skates, and sawfish) and Holocephali ( chimaeras, sometimes called ghost sharks, which are sometimes separated into their own class). Within the infraphylum Gnathostomata, cartilaginous fishes are distinct from all other jawed vertebrates. Anatomy Skeleton The skeleton is cartilaginous. The notochord is gradually replaced by a vertebral column during development, except in Holocephali, where the notochord stays intact. In some deepwater ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Late 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 al ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cleveland Shale
The Cleveland Shale, also referred to as the Cleveland Member, is a shale geologic formation in the eastern United States. Identification and name The Cleveland Shale was identified in 1870 and named for the city of Cleveland, Ohio. John Strong Newberry, director of the Ohio State Geological Survey, first identified the formation in 1870. He called it the "Cleveland Shale" and designated its type locality at Doan Brook near Cleveland. Details of the type locality and of stratigraphic nomenclature for this unit as used by the U.S. Geological Survey are available on-line at the National Geologic Map Database. Description The primary minerals in the Cleveland Shale are chlorite, illite, pyrite, and quartz. Underground, the Cleveland Shale is black, dull grayish-black, bluish-black, or brownish-black in color. In exposed outcrops, it weathers to red, reddish-brown, or medium brown. Highly weathered rock turns gray. It is fairly fissile, breaking into thin, irregularly shaped ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Symmoriiformes
Symmoriiformes is an extinct order of holocephalians. Originally named Symmoriida by Zangerl (1981), it has subsequently been known by several other names. Lund (1986) synonymized the group with Cladodontida, while Maisey (2008) corrected the name to Symmoriiformes in order to prevent it from being mistaken for a family. The symmoriiform fossils record appear at the beginning of the Carboniferous. Most of them died out at the start of the Permian, but ''Dwykaselachus'' is known from the Artinskian-Kungurian of South Africa. Teeth described from the Valanginian of France and Austria indicate that members of the family Falcatidae might have survived until the Early Cretaceous; however, these teeth were also argued to be more likely neoselachian teeth. Fossil distribution Fossil evidence of Symmoriida have been found at Bear Gulch, Fergus County, Montana, Bethel Quarry, Pike County, Indiana, Kinshozan quarry, Alaska, Gifu Prefecture, Japan, Bashkortostan, Russian Federation and pos ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Frilled Shark
The frilled shark (''Chlamydoselachus anguineus'') and the southern African frilled shark (''Chlamydoselachus africana'') are the two extant species of shark in the family '' Chlamydoselachidae''. The frilled shark is considered a living fossil, because of its primitive, anguilliform (eel-like) physical traits, such as a dark-brown color, amphistyly (the articulation of the jaws to the cranium), and a –long body, which has dorsal, pelvic, and anal fins located towards the tail. The common name, ''frilled shark'', derives from the fringed appearance of the six pairs of gill slits at the shark's throat. The two species of frilled shark are distributed throughout regions of the Atlantic and the Pacific oceans, usually in the waters of the outer continental shelf and of the upper continental slope, where the sharks usually live near the ocean floor, near biologically productive areas of the ecosystem. To live on a diet of cephalopods, smaller sharks, and bony fish, the frilled s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fossil
A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserved in amber, hair, petrified wood and DNA remnants. The totality of fossils is known as the ''fossil record''. Paleontology is the study of fossils: their age, method of formation, and evolutionary significance. Specimens are usually considered to be fossils if they are over 10,000 years old. The oldest fossils are around 3.48 billion years old to 4.1 billion years old. Early edition, published online before print. The observation in the 19th century that certain fossils were associated with certain rock strata led to the recognition of a geological timescale and the relative ages of different fossils. The development of radiometric dating techniques in the early 20th century allowed scientists to quantitatively measure the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lake Erie
Lake Erie ( "eerie") is the fourth largest lake by surface area of the five Great Lakes in North America and the eleventh-largest globally. It is the southernmost, shallowest, and smallest by volume of the Great Lakes and therefore also has the shortest average water residence time. At its deepest point Lake Erie is deep. Situated on the International Boundary between Canada and the United States, Lake Erie's northern shore is the Canadian province of Ontario, specifically the Ontario Peninsula, with the U.S. states of Michigan, Ohio, Pennsylvania, and New York on its western, southern, and eastern shores. These jurisdictions divide the surface area of the lake with water boundaries. The largest city on the lake is Cleveland, anchoring the third largest U.S. metro area in the Great Lakes region, after Greater Chicago and Metro Detroit. Other major cities along the lake shore include Buffalo, New York; Erie, Pennsylvania; and Toledo, Ohio. Situated below Lake Huron, Erie's p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kidney
The kidneys are two reddish-brown bean-shaped organs found in vertebrates. They are located on the left and right in the retroperitoneal space, and in adult humans are about in length. They receive blood from the paired renal arteries; blood exits into the paired renal veins. Each kidney is attached to a ureter, a tube that carries excreted urine to the bladder. The kidney participates in the control of the volume of various body fluids, fluid osmolality, acid–base balance, various electrolyte concentrations, and removal of toxins. Filtration occurs in the glomerulus: one-fifth of the blood volume that enters the kidneys is filtered. Examples of substances reabsorbed are solute-free water, sodium, bicarbonate, glucose, and amino acids. Examples of substances secreted are hydrogen, ammonium, potassium and uric acid. The nephron is the structural and functional unit of the kidney. Each adult human kidney contains around 1 million nephrons, while a mouse kidney contains on ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Famennian
The Famennian is the latter of two faunal stages in the Late Devonian Epoch. The most recent estimate for its duration estimates that it lasted from around 371.1 million years ago to 359.3 million years ago. An earlier 2012 estimate, still used by the International Commission on Stratigraphy, estimated that it lasted from million years ago to million years ago. It was preceded by the Frasnian stage and followed by the Tournaisian stage. Major events In the seas, a novel major group of ammonoid cephalopods called clymeniids appeared, underwent tremendous diversification and spread worldwide, then just as suddenly went extinct. The beginning of the Famennian is marked by the final stages of a major extinction event, the Kellwasser Event, which is the largest component of the Late Devonian Mass extinction. The end of the Famennian experiences a smaller but still quite severe extinction event, the Hangenberg Event. A brief episode of glaciation, possibly linked to the Hangenber ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
