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Saber-toothed Predator
A saber-tooth (alternatively spelled sabre-tooth) is any member of various extinct groups of predatory therapsids, predominantly carnivoran mammals, that are characterized by long, curved saber-shaped canine teeth which protruded from the mouth when closed. Saber-toothed mammals have been found almost worldwide from the Eocene epoch to the end of the Pleistocene epoch 42 million years ago ( mya) – 11,000 years ago (kya). One of the best-known genera is the machairodont or "saber-toothed cat" ''Smilodon'', the species of which, especially ''S. fatalis'', are popularly referred to as "saber-toothed tigers", although they are not closely related to tigers ('' Panthera''). Despite some similarities, not all saber-tooths are closely related to saber-toothed cats or felids in-general. Instead, many members are classified into different families of Feliformia, such as Barbourofelidae and Nimravidae; the oxyaenid "creodont" genera ''Machaeroides'' and '' Apataelurus''; and two exti ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Saber Tooth 2
A sabre (French language, French: Help:IPA/French, [ˈsabʁ], or saber in American English) is a type of backsword with a curved blade associated with the light cavalry of the Early Modern warfare, early modern and Napoleonic period, Napoleonic periods. Originally associated with Central European cavalry such as the hussars, the sabre became widespread in Western Europe during the Thirty Years' War. Lighter sabres also became popular with infantry of the early 17th century. In the 19th century, models with less curving blades became common and were also used by heavy cavalry. The military sabre was used as a duelling weapon in academic fencing in the 19th century, giving rise to a discipline of modern Sabre (fencing), sabre fencing (introduced in the Fencing at the 1896 Summer Olympics, 1896 Summer Olympics) loosely based on the characteristics of the historical weapon in that it allows for cuts as well as thrusts. Etymology The English ''sabre'' is recorded from the 1670s, a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Oxyaenidae
Oxyaenidae ("sharp hyenas") is a family of extinct carnivorous placental mammals. Traditionally classified in order Creodonta, this group is now classified in its own order Oxyaenodonta ("sharp tooth hyenas") within clade Pan-Carnivora in mirorder Ferae. The group contains four subfamilies comprising fourteen genera. Oxyaenids were the first to appear during the late Paleocene in North America, while smaller radiations of oxyaenids in Europe and Asia occurred during the Eocene. Etymology The name of order Oxyaenodonta comes , name of hyena genus ''Hyaena'' and . The name of family Oxyaenidae comes , name of hyena genus ''Hyaena'' and taxonomic suffix ":wikt:-idae#Suffix, -idae". Description They were superficially cat-like mammals that plantigrade, walked on flat feet, in contrast to modern cats, which digitigrade, walk and run on their toes. Anatomically, characteristic features include a short, broad skull, deep jaws, and teeth designed for crushing rather than shearing, as in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
La Brea Tar Pits
La Brea Tar Pits is an active paleontological research site in urban Los Angeles. Hancock Park was formed around a group of tar pits where natural asphalt (also called asphaltum, bitumen, or pitch; ''brea'' in Spanish) has seeped up from the ground for tens of thousands of years. Over many centuries, the bones of trapped animals have been preserved. The George C. Page Museum is dedicated to researching the tar pits and displaying specimens from the animals that died there. La Brea Tar Pits is a registered National Natural Landmark. Formation Tar pits are composed of heavy oil fractions called gilsonite, which seeps from the Earth as oil. Crude oil seeps up along the 6th Street Fault from the Salt Lake Oil Field, which underlies much of the Fairfax District north of Hancock Park. The oil reaches the surface and forms pools, becoming asphalt as the lighter fractions of the petroleum biodegrade or evaporate. The asphalt then normally hardens into stubby mounds. The pools and mou ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mammoth
A mammoth is any species of the extinct elephantid genus ''Mammuthus'', one of the many genera that make up the order of trunked mammals called proboscideans. The various species of mammoth were commonly equipped with long, curved tusks and, in northern species, a covering of long hair. They lived from the Pliocene epoch (from around 5 million years ago) into the Holocene at about 4,000 years ago, and various species existed in Africa, Europe, Asia, and North America. They were members of the family Elephantidae, which also contains the two genera of modern elephants and their ancestors. Mammoths are more closely related to living Asian elephants than African elephants. The oldest representative of ''Mammuthus'', the South African mammoth (''M. subplanifrons''), appeared around 5 million years ago during the early Pliocene in what is now southern and eastern Africa. Descendant species of these mammoths moved north and continued to propagate into numerous subsequent spe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ground Sloth
Ground sloths are a diverse group of extinct sloths in the mammalian superorder Xenarthra. The term is used to refer to all extinct sloths because of the large size of the earliest forms discovered, compared to existing tree sloths. The Caribbean ground sloths, the most recent survivors, lived in the Antilles, possibly until 1550 BCE. However, radiocarbon dating suggests an age of between 2819 and 2660 BCE for the last occurrence of ''Megalocnus'' in Cuba. Ground sloths had been extinct on the mainland of North and South America for 10,000 years or more. They survived 5,000–6,000 years longer in the Caribbean than on the American mainland, which correlates with the later colonization of this area by humans. Much ground sloth evolution took place during the late Paleogene and Neogene of South America, while the continent was isolated. At their earliest appearance in the fossil record, the ground sloths were already distinct at the family level. The presence ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Maxillary Canine
In human dentistry, the maxillary canine is the tooth located laterally (away from the midline of the face) from both maxillary lateral incisors of the mouth but mesial (toward the midline of the face) from both maxillary first premolars. Both the maxillary and mandibular canines are called the "cornerstone" of the mouth because they are all located three teeth away from the midline, and separate the premolars from the incisors. The location of the canines reflect their dual function as they complement both the premolars and incisors during mastication, commonly known as chewing. Nonetheless, the most common action of the canines is tearing of food. The canines often erupt in the upper gums several millimeters above the gum line. The canine teeth are able to withstand the tremendous lateral pressure caused by chewing. There is a single cusp on canines, and they resemble the prehensile teeth found in carnivorous animals such as the extinct saber-toothed cat. Though relatively the s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Convergent Evolution
Convergent evolution is the independent evolution of similar features in species of different periods or epochs in time. Convergent evolution creates analogous structures that have similar form or function but were not present in the last common ancestor of those groups. The cladistic term for the same phenomenon is homoplasy. The recurrent evolution of flight is a classic example, as flying insects, birds, pterosaurs, and bats have independently evolved the useful capacity of flight. Functionally similar features that have arisen through convergent evolution are ''analogous'', whereas '' homologous'' structures or traits have a common origin but can have dissimilar functions. Bird, bat, and pterosaur wings are analogous structures, but their forelimbs are homologous, sharing an ancestral state despite serving different functions. The opposite of convergence is divergent evolution, where related species evolve different traits. Convergent evolution is similar to parallel evo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Marsupial
Marsupials are any members of the mammalian infraclass Marsupialia. All extant marsupials are endemic to Australasia, Wallacea and the Americas. A distinctive characteristic common to most of these species is that the young are carried in a pouch. Marsupials include opossums, Tasmanian devils, kangaroos, koalas, wombats, wallabies, bandicoots, and the extinct thylacine. Marsupials represent the clade originating from the last common ancestor of extant metatherians, the group containing all mammals more closely related to marsupials than to placentals. They give birth to relatively undeveloped young that often reside in a pouch located on their mothers' abdomen for a certain amount of time. Close to 70% of the 334 extant species occur on the Australian continent (the mainland, Tasmania, New Guinea and nearby islands). The remaining 30% are found in the Americas—primarily in South America, thirteen in Central America, and one species, the Virginia opossum, in North America, n ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Deltatheroida
Deltatheroida is an extinct group of basal metatherians that were distantly related to modern marsupials. The majority of known members of the group lived in the Cretaceous; one species, '' Gurbanodelta kara'', is known from the late Paleocene (Gashatan) of China. Their fossils are restricted to Central Asia and North America. This order can be defined as all metatherians closer to ''Deltatheridium'' than to Marsupialia. These mammals possessed primitive tritubercular (three-cusped) lower molars that were not tribosphenic. This is awkward because tribosphenic molars are commonly found in most therian mammals (there exist some exceptions such as anteaters and some whales, which have no teeth at all). When they were first identified in the 1920s, they were believed to be placentals and possible ancestors of the "creodonts" (a polyphyletic group of extinct carnivorous mammals from the Paleogene and Miocene), but this was later disproven. Nonetheless, deltatheroideans do converge on ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sparassodonta
Sparassodonta (from Ancient Greek, Greek ['], to tear, rend; and , gen. [', '], tooth) is an extinct order (biology), order of carnivore, carnivorous metatherian mammals native to South America, related to modern marsupials. They were once considered to be true marsupials, but are now thought to be a separate side branch that split before the last common ancestor of all modern marsupials. A number of these mammalian predators closely resemble placental predators that evolved separately on other continents, and are cited frequently as examples of convergent evolution. They were first described by Florentino Ameghino, from fossils found in the Santa Cruz beds of Patagonia. Sparassodonts were present throughout South America's long period of "splendid isolation" during the Cenozoic; during this time, they shared the niches for large warm-blooded predators with the flightless Phorusrhacidae, terror birds. Previously, it was thought that these mammals died out in the face of competit ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Thylacosmilidae
Thylacosmilidae is an extinct Family (biology), family of metatherian predators, related to the modern marsupials, which lived in South America between the Miocene and Pliocene epochs. Like other South American mammalian predators that lived prior to the Great American Biotic Interchange, these animals belonged to the order Sparassodonta, which occupied the ecological niche of many eutherian mammals of the order Carnivora from other continents. The family's most notable feature are the elongated, laterally flattened fangs, which is a remarkable evolutionary convergence with other saber-toothed mammals like ''Barbourofelis'' and ''Smilodon''. Taxonomic history The family Thylacosmilidae was originally erected by Riggs in 1933, to accommodate ''Thylacosmilus'', found in the Pliocene Brochero Formation of Argentina. Later, the family was demoted to a subfamily, as Thylacosmilinae, within Borhyaenidae, a group of superficially canid-like sparassodonts, under the assumption that '' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Metatheria
Metatheria is a mammalian clade that includes all mammals more closely related to marsupials than to placentals. First proposed by Thomas Henry Huxley in 1880, it is a more inclusive group than the marsupials; it contains all marsupials as well as many extinct non-marsupial relatives. There are three extant subclasses of mammals, one being metatherians: #monotremes: egg laying mammals like the platypus and the echidna, #metatheria: marsupials, which includes three American orders ( Didelphimorphia, Paucituberculata and Microbiotheria) and four Australasian orders (Notoryctemorphia, Dasyuromorphia, Peramelemorphia and Diprotodontia), and the # eutherians: placental mammals, consisting of four superorders divided into 21 orders. Metatherians belong to a subgroup of the northern tribosphenic mammal clade or Boreosphenida. They differ from all other mammals in certain morphologies like their dental formula, which includes about five upper and four lower incisors, a canine, three pre ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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