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Cyclurus
''Cyclurus'' (Ancient Greek for "rounded tail") is an extinct genus of freshwater Amiidae, amiid Actinopterygii, ray-finned fish known from the Late Cretaceous to the Rupelian, Early Oligocene across much of the Northern Hemisphere. It is thought to be the closest relative of the extant Bowfin, bowfins in the genus ''Amia (fish), Amia'', although species of ''Cyclurus'' were significantly smaller in size compared to ''Amia''. Evolution Remains of ''Cyclurus'' are first known from western North America during the Maastrichtian stage of the Cretaceous with the species ''C. fragosus'', with the genus having presumably diverged from ''Amia (fish), Amia'' shortly before. Potential earlier remains are known from the Campanian. Alongside ''Amia'', ''Cyclurus'' survived the Cretaceous–Paleogene extinction event, Cretaceous-Paleogene extinction event in a Refugium (population biology), refugium in western North America. Shortly afterwards, it saw a dramatic range expansion over the Pa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Amia (fish)
''Amia'', commonly called bowfin, is a genus of Actinopterygii, ray-finned fish related to gars in the infraclass Holostei. They are regarded as taxonomy (biology), taxonomic relict species, relicts, being the sole surviving species of the order (biology), order Amiiformes and clade Halecomorphi, which dates from the Triassic to the Eocene, persisting to the present. There are two living species in ''Amia'', ''Amia calva'' and ''Amia ocellicauda'', and a number of extinct species which have been described from the fossil record. Etymology The genus name ''Amia'' derives from the Ancient Greek and Latin name for an unknown fish (most likely the Atlantic bonito) referred to by ancient and medieval authors including Pliny the Elder, Isidore of Seville, and Thomas of Cantimpré. Evolution and phylogeny ''Amia'' is thought to have diverged from its Sister group, sister genus, ''Cyclurus'', during the Late Cretaceous. These two genera, their sister amiine ''Pseudoamiatus'', and the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Amiidae
The Amiidae are a family of basal ray-finned fishes. The bowfin and the eyespot bowfin ('' Amia ocellicauda'') are the only two species to survive today, although additional species in all four subfamilies of Amiidae are known from Jurassic, Cretaceous, and Eocene fossils. Bowfins are now found throughout eastern North America, typically in slow-moving backwaters, canals, and ox-bow lakes. When the oxygen level is low (as often happens in still waters), the bowfin can rise to the surface and gulp air into its swim bladder, which is lined with blood vessels and can serve as a primitive lung. Amiidae is a monophyletic group that has numerous synapomorphic characters. Amiidae were widespread and particularly rich in species during the Eocene era. During this era, they appeared to be confined almost exclusively to fresh water. Taxonomy The family is divided into five subfamilies, with 16 genera *Amiidae **Subfamily Amiinae (latest Cretaceous -Present) ***Genus '' Amia'' ***Genus ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ivan Yefremov
Ivan Antonovich (Antipovich) Yefremov, sometimes Efremov (; 23 April 1908 – 5 October 1972) was a Soviet paleontologist, science-fiction author and social thinker. He founded taphonomy, the study of fossilization patterns. Biography He was born in the village of Vyritsa in Saint Petersburg Governorate on 23 April 1908. His parents divorced during the Russian Revolution. His mother married a Red Army commander and left the children in Kherson to be cared for by an aunt who soon died of typhus. Yefremov survived on his own for some time, after which he joined a Red Army unit as a "son of the regiment" and went to Perekop with it. In 1921, he was discharged and went to Petrograd (now Saint Petersburg) to study. He completed his education there while combining his studies with a variety of odd jobs. He later commented that "the Revolution was also my own liberation from philistinism" (). Academic career In 1956, due to the influence of academician Petr Sushkin, he bec ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Maastrichtian
The Maastrichtian ( ) is, in the International Commission on Stratigraphy (ICS) geologic timescale, the latest age (geology), age (uppermost stage (stratigraphy), stage) of the Late Cretaceous epoch (geology), Epoch or Upper Cretaceous series (stratigraphy), Series, the Cretaceous geologic period, Period or system (stratigraphy), System, and of the Mesozoic geologic era, Era or Erathem. It spanned the interval from . The Maastrichtian was preceded by the Campanian and succeeded by the Danian (part of the Paleogene and Paleocene). It is named after the city of Maastricht, the capital and largest city of the Limburg (Netherlands), Limburg province in the Netherlands. The Cretaceous–Paleogene extinction event (formerly known as the Cretaceous–Tertiary period, Tertiary extinction event) occurred at the end of this age. In this extinction event, mass extinction, many commonly recognized groups such as non-avian dinosaurs, plesiosaurs and mosasaurs, as well as many other lesser-kn ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Thanetian
The Thanetian is, in the International Commission on Stratigraphy, ICS Geologic timescale, the latest age (geology), age or uppermost stage (stratigraphy), stratigraphic stage of the Paleocene epoch (geology), Epoch or series (stratigraphy), Series. It spans the time between . The Thanetian is preceded by the Selandian Age and followed by the Ypresian Age (part of the Eocene). The Thanetian is sometimes referred to as the Late Paleocene. Stratigraphic definition The Thanetian was established by Switzerland, Swiss geologist Eugène Renevier in 1873. The Thanetian is named after the Thanet Formation, the oldest Cenozoic deposit of the London Basin, which was first identified in the area of Kent (southern England) known as the Isle of Thanet. The base of the Thanetian Stage is laid at the base of magnetic chronozone C26n. The references profile (Global Boundary Stratotype Section and Point) is in the Zumaia section (43° 18'N, 2° 16'W) at the beach of Itzurun, Pais Vasco, northern ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hell Creek Formation
The Hell Creek Formation is an intensively studied division of mostly Upper Cretaceous and some lower Paleocene rocks in North America, named for exposures studied along Hell Creek, near Jordan, Montana. The Formation (stratigraphy), formation stretches over portions of Montana, North Dakota, South Dakota, and Wyoming. In Montana, the Hell Creek Formation overlies the Fox Hills Formation. The site of Pompeys Pillar National Monument is a small isolated section of the Hell Creek Formation. In 1966, the Hell Creek Fossil Area was designated as a National Natural Landmark by the National Park Service. It is a series of fresh and brackish-water clays, mudstones, and sandstones deposited during the Maastrichtian and Danian (respectively, the end of the Cretaceous period and the beginning of the Paleogene) by fluvial activity in fluctuating river channels and deltas and very occasional peaty swamp deposits along the low-lying eastern continental margin fronting the late Cretaceous West ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Wyoming
Wyoming ( ) is a landlocked U.S. state, state in the Mountain states, Mountain West subregion of the Western United States, Western United States. It borders Montana to the north and northwest, South Dakota and Nebraska to the east, Idaho to the west, Utah to the southwest, and Colorado to the south. With an estimated population of 587,618 as of 2024, Wyoming is the List of U.S. states and territories by population, least populous state despite being the List of U.S. states and territories by area, 10th largest by area, and it has the List of U.S. states by population density, second-lowest population density after Alaska. The List of capitals in the United States, state capital and List of municipalities in Wyoming, most populous city is Cheyenne, Wyoming, Cheyenne, which had a population of 65,132 in 2020. Wyoming's western half consists mostly of the ranges and rangelands of the Rocky Mountains; its eastern half consists of high-elevation prairie, and is referred to as th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
South Dakota
South Dakota (; Sioux language, Sioux: , ) is a U.S. state, state in the West North Central states, North Central region of the United States. It is also part of the Great Plains. South Dakota is named after the Dakota people, Dakota Sioux tribe, which comprises a large portion of the population—with nine Indian reservation, reservations in the state—and has historically dominated the territory. South Dakota is the List of U.S. states and territories by area, 17th-largest by area, the List of U.S. states and territories by population, fifth-least populous, and the List of U.S. states and territories by population density, fifth-least densely populated of the List of U.S. states, 50 United States. Pierre, South Dakota, Pierre is the List of capitals in the United States, state capital, and Sioux Falls, South Dakota, Sioux Falls, with a population of about 213,900, is South Dakota's List of cities in South Dakota, most populous city. The state is bisected by the Missouri Ri ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
North Dakota
North Dakota ( ) is a U.S. state in the Upper Midwest, named after the indigenous Dakota people, Dakota and Sioux peoples. It is bordered by the Canadian provinces of Saskatchewan and Manitoba to the north and by the U.S. states of Minnesota to the east, South Dakota to the south, and Montana to the west. North Dakota is part of the Great Plains region, characterized by broad prairies, steppe, temperate savanna, badlands, and farmland. North Dakota is the List of U.S. states and territories by area, 19th-largest state by area, but with a population of just under 800,000, the List of U.S. states and territories by population, fourth-least populous and List of U.S. states by population density, fourth-least densely populated. The List of capitals in the United States, state capital is Bismarck, North Dakota, Bismarck and the List of cities in North Dakota, most populous city is Fargo, North Dakota, Fargo, which accounts for nearly a fifth of the state's population; both cities ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Montana
Montana ( ) is a landlocked U.S. state, state in the Mountain states, Mountain West subregion of the Western United States. It is bordered by Idaho to the west, North Dakota to the east, South Dakota to the southeast, Wyoming to the south, and the Provinces and territories of Canada, Canadian provinces of Alberta, British Columbia, and Saskatchewan to the north. It is the List of U.S. states and territories by area, fourth-largest state by area, but the List of U.S. states and territories by population, eighth-least populous state and the List of U.S. states and territories by population density, third-least densely populated state. Its List of capitals in the United States, capital is Helena, Montana, Helena, while the List of municipalities in Montana, most populous city is Billings, Montana, Billings. The western half of the state contains numerous mountain ranges, while the eastern half is characterized by western prairie terrain and badlands, with smaller mountain ranges f ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Scollard Formation
The Scollard Formation is an Upper Cretaceous to lower Palaeocene stratigraphic unit of the Western Canada Sedimentary Basin in southwestern Alberta. Its deposition spanned the time interval from latest Cretaceous to early Paleocene, and it includes sediments that were deposited before, during, and after the Cretaceous-Paleogene (K-Pg) extinction event. It is significant for its fossil record, and it includes the economically important coal deposits of the Ardley coal zone. Lithology The Scollard Formation consists primarily of sandstones and siltstones, interbedded with mudstones and, in the upper portion, coal seams, as well as minor amounts of bentonite. The sediments were eroded from the Canadian Cordillera, and were transported eastward by river systems and deposited in fluvial channel and floodplain environments. Stratigraphy The Scollard is usually classified as the uppermost formation of the Edmonton Group, although some early workers included it in the overlying ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Alberta
Alberta is a Provinces and territories of Canada, province in Canada. It is a part of Western Canada and is one of the three Canadian Prairies, prairie provinces. Alberta is bordered by British Columbia to its west, Saskatchewan to its east, the Northwest Territories to its north, and the U.S. state of Montana to its south. Alberta and Saskatchewan are the only two landlocked Canadian provinces. The eastern part of the province is occupied by the Great Plains, while the western part borders the Rocky Mountains. The province has a predominantly humid continental climate, continental climate, but seasonal temperatures tend to swing rapidly because it is so arid. Those swings are less pronounced in western Alberta because of its occasional Chinook winds. Alberta is the fourth largest province by area, at , and the fourth most populous, with 4,262,635 residents. Alberta's capital is Edmonton; its largest city is Calgary. The two cities are Alberta's largest Census geographic units ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
