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Falcatus Falcatus 01
''Falcatus'' is an extinct genus of falcatid chondrichthyan which lived during the early Carboniferous Period in Bear Gulch bay in what is now Montana. Description This fish was quite small, only getting to around 25–30 cm or 10-12 inches long. This is about as big as some of the smallest sharks around today, like the pygmy laternshark. Falcatus was a chondricthian known as a "cladodont-toothed stethacanthid holocephalan". The first material known from the genus were the prominent fin spines that curve anteriorly over the head of the animal. When first described in 1883 from the St. Louis Limestone, these remains were given the name ''Physonemus falcatus''. However, in 1985, fossils of a new type of condrichthyan from Montana were described that displayed a high degree of sexual dimorphism. The same spines that were previously named ''P. falcatus'' were found on one of the morphs, identified as the male due to the presence of valvae.The morphology of ''Falcatus fal ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Viséan
The Visean, Viséan or Visian is an age in the ICS geologic timescale or a stage in the stratigraphic column. It is the second stage of the Mississippian, the lower subsystem of the Carboniferous. The Visean lasted from to Ma. It follows the Tournaisian age/stage and is followed by the Serpukhovian age/stage. Name and definitions The Viséan Stage was introduced by Belgian geologist André Dumont in 1832. Dumont named this stage after the city of Visé in Belgium's Liège Province. Before being used as an international stage, the Visean Stage was part of the (West) European regional geologic time scale, in which it followed the Tournaisian Stage and is followed by the Namurian Stage. In the North American regional scale, the Visean Stage correlates with the upper Osagean, the Meramecian and lower Chesterian stages. In the Chinese regional time scale, it correlates with the lower and middle Tatangian series.; 2006: ''Global time scale and regional stratigraphic reference sca ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chimaera
Chimaeras are cartilaginous fish in the order Chimaeriformes , known informally as ghost sharks, rat fish, spookfish, or rabbit fish; the last three names are not to be confused with rattails, Opisthoproctidae, or Siganidae, respectively. At one time a "diverse and abundant" group (based on the fossil record), their closest living relatives are sharks and rays, though their last common ancestor with them lived nearly 400 million years ago. Today, they are largely confined to deep water. Description and habits Chimaeras live in temperate ocean floors down to deep, with few occurring at depths shallower than . Exceptions include the members of the genus ''Callorhinchus'', the rabbit fish and the spotted ratfish, which locally or periodically can be found at shallower depths. Consequently, these are also among the few species from the chimaera order kept in public aquaria. They live in all the oceans except for the Arctic and Antarctic oceans. They have elongated, soft ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Delphyodontos
''Delphyodontos dacriformes'' is a prehistoric holocephalid fish from the middle Carboniferous-aged Bear Gulch Limestone Lagerstätte, during the Bashkirian Stage in Montana. The adult form is unknown, as the only fossil specimens are of aborted fetuses or recently born young.Lund, R. 1980. Viviparity and intrauterine feeding in a new holocephalan fish from the Lower Carboniferous of Montana. Science, 209: 697‑699. Sharp teeth and fecal matter in the fossils suggests that ''Delphyodontos'' practiced intrauterine cannibalism, like some modern sharks, such as sand tiger shark The sand tiger shark (''Carcharias taurus''), gray nurse shark, spotted ragged-tooth shark or blue-nurse sand tiger, is a species of shark that inhabits subtropical and temperate waters worldwide. It inhabits the continental shelf, from sandy sho ...s. Appearance According to the fossils, the recently born would have resembled tadpoles with small, but sharp beaks. Because of the evidence suggesting int ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Listracanthus
''Listracanthus'' is a genus of extinct chondrichthyan with uncertain affinities. Species of ''Listracanthus'' are known primarily from their tremendous, feather-like denticles, which range up to four inches in length. The denticles had a large main spine, from which secondary spines emanate from the sides, like the barbs of a feather or a comb. ''Listracanthus'' first appeared in late Carboniferous strata in North America, and eventually disappear from the fossil record some time during the Early Triassic. The appearance of these sharks are largely unknown. However, author and illustrator Ray Troll Ray Troll (born March 4, 1954) is an American artist based in Ketchikan, Alaska. He is best known for his scientifically accurate and often humorous artwork. His most well-known design is "Spawn Till You Die", which has appeared in many places inc ... mentions in his book, ''Sharkabet'', about how paleontologist Rainer Zangerl once discovered a large shale slab containing a lo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Agassizodus
''Agassizodus'' is an extinct genus of eugeneodont holocephalan from the Carboniferous. It belongs to the family Helicoprionidae, which is sometimes called Agassizodontidae. Like other members of its family, it possessed a symphyseal tooth whorl, which was likely present at the tip of the lower jaw and associated with lateral crushing toothplates. The type species, ''A. variabilis'', was originally named ''Lophodus variabilis'' until the name "Lophodus" was determined to be preoccupied. ''A. variabilis'' was originally based on tooth fragments from the Pennsylvanian of Illinois, but the authors who named the genus (St. John and Worthen, 1875) also referred a massive jaw from Osage County, Kansas Osage County (county code OS) is a county located in the U.S. state of Kansas. As of the 2020 census, the county population was 15,766. Its county seat is Lyndon, and its most populous city is Osage City. The county was originally organized i .... The Osage jaw shared some simi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Oxygen
Oxygen is the chemical element with the symbol O and atomic number 8. It is a member of the chalcogen group in the periodic table, a highly reactive nonmetal, and an oxidizing agent that readily forms oxides with most elements as well as with other compounds. Oxygen is Earth's most abundant element, and after hydrogen and helium, it is the third-most abundant element in the universe. At standard temperature and pressure, two atoms of the element bind to form dioxygen, a colorless and odorless diatomic gas with the formula . Diatomic oxygen gas currently constitutes 20.95% of the Earth's atmosphere, though this has changed considerably over long periods of time. Oxygen makes up almost half of the Earth's crust in the form of oxides.Atkins, P.; Jones, L.; Laverman, L. (2016).''Chemical Principles'', 7th edition. Freeman. Many major classes of organic molecules in living organisms contain oxygen atoms, such as proteins, nucleic acids, carbohydrates, and fats, as ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Asphyxia
Asphyxia or asphyxiation is a condition of deficient supply of oxygen to the body which arises from abnormal breathing. Asphyxia causes generalized hypoxia, which affects primarily the tissues and organs. There are many circumstances that can induce asphyxia, all of which are characterized by the inability of a person to acquire sufficient oxygen through breathing for an extended period of time. Asphyxia can cause coma or death. In 2015, about 9.8 million cases of unintentional suffocation occurred which resulted in 35,600 deaths. The word asphyxia is from Ancient Greek "without" and , "squeeze" (throb of heart). Causes Situations that can cause asphyxia include but are not limited to: airway obstruction, the constriction or obstruction of airways, such as from asthma, laryngospasm, or simple blockage from the presence of foreign materials; from being in environments where oxygen is not readily accessible: such as underwater, in a low oxygen atmosphere, or in a vacuum; envir ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lagoon
A lagoon is a shallow body of water separated from a larger body of water by a narrow landform, such as reefs, barrier islands, barrier peninsulas, or isthmuses. Lagoons are commonly divided into ''coastal lagoons'' (or ''barrier lagoons'') and ''atoll lagoons''. They have also been identified as occurring on mixed-sand and gravel coastlines. There is an overlap between bodies of water classified as coastal lagoons and bodies of water classified as estuaries. Lagoons are common coastal features around many parts of the world. Definition and terminology Lagoons are shallow, often elongated bodies of water separated from a larger body of water by a shallow or exposed shoal, coral reef, or similar feature. Some authorities include fresh water bodies in the definition of "lagoon", while others explicitly restrict "lagoon" to bodies of water with some degree of salinity. The distinction between "lagoon" and "estuary" also varies between authorities. Richard A. Davis Jr. restrict ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mudflat
Mudflats or mud flats, also known as tidal flats or, in Ireland, slob or slobs, are coastal wetlands that form in intertidal areas where sediments have been deposited by tides or rivers. A global analysis published in 2019 suggested that tidal flat ecosystems are as extensive globally as mangroves, covering at least of the Earth's surface. / They are found in sheltered areas such as bays, bayous, lagoons, and estuaries; they are also seen in freshwater lakes and salty lakes (or inland seas) alike, wherein many rivers and creeks end. Mudflats may be viewed geologically as exposed layers of bay mud, resulting from deposition of estuarine silts, clays and aquatic animal detritus. Most of the sediment within a mudflat is within the intertidal zone, and thus the flat is submerged and exposed approximately twice daily. A recent global remote sensing analysis estimated that approximately 50% of the global extent of tidal flats occurs within eight countries (Indonesia, China, Austral ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Big Snowy Mountains
The Big Snowy Mountains ( ats, níichʔibííkʔa, lit=it is never summer) are a small mountain range south of Lewistown in Fergus County, Montana. Considerably east of and isolated from the main crest of the Northern Rockies, they are one of the few points of significant elevation in the immediate area and are considered one of Montana's island ranges. The range's highest elevation is . The smaller Little Snowy Mountains are a contiguous range immediately to the east. About 112,000 acres of the Big Snowies are roadless, the bulk of this on the Lewis and Clark National Forest, as well as 6,870 acres in the Twin Coulees Wilderness Study Area on adjacent BLM land; 98,000 acres of the National Forest land are also a Wilderness Study Area. The Big Snowies feature a long, relatively level east-west summit ridge, rising above timberline, that culminates in Greathouse Peak, the highest point in the range. On a clear day the view from the top of Greathouse Peak extends from Canada to Y ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cretaceous
The Cretaceous ( ) is a geological period that lasted from about 145 to 66 million years ago (Mya). It is the third and final period of the Mesozoic Era, as well as the longest. At around 79 million years, it is the longest geological period of the entire Phanerozoic. The name is derived from the Latin ''creta'', "chalk", which is abundant in the latter half of the period. It is usually abbreviated K, for its German translation ''Kreide''. The Cretaceous was a period with a relatively warm climate, resulting in high eustatic sea levels that created numerous shallow inland seas. These oceans and seas were populated with now- extinct marine reptiles, ammonites, and rudists, while dinosaurs continued to dominate on land. The world was ice free, and forests extended to the poles. During this time, new groups of mammals and birds appeared. During the Early Cretaceous, flowering plants appeared and began to rapidly diversify, becoming the dominant group of plants across the Earth b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
