|
Gypsonictopidae
''Gypsonictops'' is an extinct genus of leptictidan mammals of the family Gypsonictopidae, which was described in 1927 by George Gaylord Simpson. Species in this genus were small mammals and the first representatives of the order Leptictida, that appeared during the Upper Cretaceous. The genus is thought to have gone extinct before the Cenozoic began, but there are indications that it may have survived into the early Paleocene. Fossils have been found in the United States, Belgium, and Uzbekistan. Like ''Cimolestes'' or '' Daulestes'', it is possible that they had some distant relationship with the ungulates. It is one of the few eutherians that existed in North America during the Campanian, a period in which the multituberculates and the metatherians were the dominant ones on the continent. Description Like other prehistoric mammals of the Upper Cretaceous in North America, ''Gypsonictops'' had a particular dentition, with five premolars double-rooted in the lower jaw, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Leptictida
Leptictida (''leptos iktis'' "small/slender weasel") is a possibly paraphyletic extinct order of eutherian mammals. Their classification is contentious: according to cladistic studies, they may be (distantly) related to Euarchontoglires (rodents, primates and their relatives), although they are more recently regarded as the first branch to split from basal eutherians. One recent large-scale cladistic analysis of eutherian mammals favored lepictidans as close to the placental crown-clade; and several other recent analyses that included data from Cretaceous non-eutherian mammals found ''Leptictis'' to belong to the superorder Afrotheria. The most recent phylogenetic studies recover it as actually a paraphyletic assemblage leading to Placentalia. Description The leptictids are a characteristic example of the non-specialized placental mammals that took part in the late Cretaceous-Paleocene evolutionary radiation, originally bunched together in the order Insectivora. The leptictids ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Paleocene
The Paleocene ( ), or Palaeocene, is a geological epoch (geology), epoch that lasted from about 66 to 56 mya (unit), million years ago (mya). It is the first epoch of the Paleogene Period (geology), Period in the modern Cenozoic Era (geology), Era. The name is a combination of the Ancient Greek ''palaiós'' meaning "old" and the Eocene Epoch (which succeeds the Paleocene), translating to "the old part of the Eocene". The epoch is bracketed by two major events in Earth's history. The K–Pg extinction event, brought on by an asteroid impact (Chicxulub impact) and possibly volcanism (Deccan Traps), marked the beginning of the Paleocene and killed off 75% of species, most famously the non-avian dinosaurs. The end of the epoch was marked by the Paleocene–Eocene Thermal Maximum (PETM), which was a major climatic event wherein about 2,500–4,500 gigatons of carbon were released into the atmosphere and ocean systems, causing a spike in global temperatures and ocean acidification. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dentition
Dentition pertains to the development of teeth and their arrangement in the mouth. In particular, it is the characteristic arrangement, kind, and number of teeth in a given species at a given age. That is, the number, type, and morpho-physiology (that is, the relationship between the shape and form of the tooth in question and its inferred function) of the teeth of an animal. Terminology Animals whose teeth are all of the same type, such as most non-mammalian vertebrates, are said to have '' homodont'' dentition, whereas those whose teeth differ morphologically are said to have '' heterodont'' dentition. The dentition of animals with two successions of teeth (deciduous, permanent) is referred to as '' diphyodont'', while the dentition of animals with only one set of teeth throughout life is ''monophyodont''. The dentition of animals in which the teeth are continuously discarded and replaced throughout life is termed '' polyphyodont''. The dentition of animals in which the teeth ... [...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] |
Hell Creek
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 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 Western Interior Seaway. T ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Placental
Placental mammals (infraclass Placentalia ) are one of the three extant subdivisions of the class Mammalia, the other two being Monotremata and Marsupialia. Placentalia contains the vast majority of extant mammals, which are partly distinguished from monotremes and marsupials in that the fetus (biology), fetus is carried in the uterus of its mother to a relatively late stage of development. The name is something of a misnomer, considering that marsupials also nourish their fetuses via a placenta, though for a relatively briefer period, giving birth to less-developed young, which are then nurtured for a period inside the mother's pouch (marsupial), pouch. Placentalia represents the only living group within Eutheria, which contains all mammals that are more closely related to placentals than they are to marsupials. Anatomical features Placental mammals are anatomically distinguished from other mammals by: * a sufficiently wide opening at the bottom of the pelvis to allow the birt ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Eutheria
Eutheria (from Greek , 'good, right' and , 'beast'; ), also called Pan-Placentalia, is the clade consisting of Placentalia, placental mammals and all therian mammals that are more closely related to placentals than to marsupials. Eutherians are distinguished from non-eutherians by various phenotypic traits of the feet, ankles, jaws and teeth. All extant eutherians lack epipubic bones, which are present in all other living mammals (marsupials and monotremes). This allows for expansion of the abdomen during pregnancy, though epipubic bones are present in many primitive eutherians. Eutheria was named in 1872 by Theodore Gill; in 1880, Thomas Henry Huxley defined it to encompass a more broadly defined group than Placentalia. The earliest unambiguous eutherians are known from the Early Cretaceous Yixian Formation of China, dating around 120 million years ago. Two tribosphenic mammals, ''Durlstodon'' and ''Durlstotherium'' from the Berriasian age (~145–140 million years ago) of t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sikuomys
''Sikuomys'' is a genus of early eutherian mammals from the Late Cretaceous of Alaska. It is known from a few teeth and part of a jawbone in deposits of Campanian age and, , is the only known Mesozoic The Mesozoic Era is the Era (geology), era of Earth's Geologic time scale, geological history, lasting from about , comprising the Triassic, Jurassic and Cretaceous Period (geology), Periods. It is characterized by the dominance of archosaurian r ... eutherian mammal to have lived north of the then location of the Arctic Circle. Estimated to have weighed between , it was also unusually small for the time, similar in size to a modern shrew. It was likely insectivorous and would probably have used burrows or nests to shelter during the Arctic winter, since it is thought to have been too small to have hibernated or migrated over significant distances. References {{Taxonbar, from=Q123985250 Late Cretaceous mammals of North America Leptictida Fossil taxa described in 2023 Prehi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Susan K
Susan is a feminine given name, the usual English version of Susanna or Susannah. All are versions of the Hebrew name Shoshana, which is derived from the Hebrew ''shoshan'', meaning ''lotus flower'' in Egyptian, original derivation, and several other languages. Variations * Susana, Susanna (or Suzanna), Susannah, Suzana, Suzannah * Susann, Sussan, Suzan, Suzann * Susanne, Suzanne * Susanne * Suzan * Suzanne * Suzette * Susie, Suzy Nicknames Common nicknames for Susan include: * Sue, Susie, Susi (German), Suzi, Suzy, Suzie, Suze, Sanna, Suzie, Sookie, Sukie, Sukey, Subo, Suus (Dutch), Shanti In other languages * Albanian and * * , or * * , or * * , or * Catalan, Estonian and * ** * Czech Czech may refer to: * Anything from or related to the Czech Republic, a country in Europe ** Czech language ** Czechs, the people of the area ** Czech culture ** Czech cuisine * One of three mythical brothers, Lech, Czech, and Rus *Czech (surnam ... and * Danish a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Malcolm C
Malcolm, Malcom, Máel Coluim, or Maol Choluim may refer to: People * Malcolm (given name), includes a list of people and fictional characters * Malcom (footballer) (born 1997), Brazilian football forward * Clan Malcolm * Maol Choluim de Innerpeffray, 14th-century bishop-elect of Dunkeld Nobility * Máel Coluim, Earl of Atholl, Mormaer of Atholl between 1153/9 and the 1190s * Máel Coluim, King of Strathclyde, 10th century * Máel Coluim of Moray, Mormaer of Moray 1020–1029 * Máel Coluim (son of the king of the Cumbrians), possible King of Strathclyde or King of Alba around 1054 * Malcolm I of Scotland (died 954), King of Scots * Malcolm II of Scotland, King of Scots from 1005 until his death * Malcolm III of Scotland, King of Scots * Malcolm IV of Scotland, King of Scots * Máel Coluim, Earl of Angus, the fifth attested post 10th-century Mormaer of Angus * Máel Coluim I, Earl of Fife, one of the more obscure Mormaers of Fife * Maol Choluim I, Earl of Lennox, Mormaer * M� ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Leigh Van Valen
Leigh Van Valen (August 12, 1935 – October 16, 2010) was an American evolutionary biologist. At the time of his death, he was professor emeritus in the Department of Ecology and Evolution at the University of Chicago. Research and interests Amongst other work, Van Valen's proposed "Law of Extinction", known as Van Valen's law, drew upon the apparent constant probability (as opposed to rate) of extinction in families of related organisms, based on data compiled from existing literature on the duration of tens of thousands of genera throughout the fossil record. Van Valen proposed the Red Queen hypothesis (1973), as an explanatory tangent to the Law of Extinction. The Red Queen Hypothesis captures the idea that there is a constant 'arms race' between co-evolving species. Its name is a reference to the Red Queen's race in Lewis Carroll's '' Through the Looking-Glass'', in which the chess board moves such that Alice must continue running just to stay in the same place. Van V ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
