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Mesonychian
Mesonychia ("middle claws") is an extinct taxon of small- to large-sized carnivorous ungulates related to artiodactyls. Mesonychids first appeared in the early Paleocene, went into a sharp decline at the end of the Eocene, and died out entirely when the last genus, ''Mongolestes'', became extinct in the early Oligocene. In Asia, the record of their history suggests they grew gradually larger and more predatory over time, then shifted to scavenging and bone-crushing lifestyles before the group became extinct. Mesonychids probably originated in China, where the most primitive mesonychid, ''Yangtanglestes'', is known from the early Paleocene. They were also most diverse in Asia, where they occur in all major Paleocene faunas. Since other predators, such as creodonts and Carnivora, were either rare or absent in these animal communities, mesonychids most likely dominated the large predator niche in the Paleocene of eastern Asia. One genus, ''Dissacus'', had successfully spread to Eur ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Carnivora
Carnivora is a Clade, monophyletic order of Placentalia, placental mammals consisting of the most recent common ancestor of all felidae, cat-like and canidae, dog-like animals, and all descendants of that ancestor. Members of this group are formally referred to as carnivorans, and have evolved to specialize in eating flesh. The order is the fifth largest order of mammals, comprising at least 279 species. Carnivorans live on every major landmass and in a variety of habitats, ranging from the cold polar regions to the hyper-arid region of the Sahara Desert to the open seas. They come in a very large array of different body plans in contrasting shapes and sizes. Carnivora can be divided into two subclades: the cat-like Feliformia and the dog-like Caniformia, which are differentiated based on the structure of their ear bones and cranial features. The feliforms include families such as the felidae, cats, the hyenas, the mongooses and the viverridae, civets. The majority of felifor ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Triisodontidae
Triisodontidae is an extinct, probably paraphyletic, or possibly invalid family of mesonychian placental mammals. Most triisodontid genera lived during the Paleocene in North America, but the genus ''Andrewsarchus'' (if it is a mesonychian, and not an artiodactyl) is known from the middle Eocene of Asia. Triisodontids were the first relatively large predatory mammals to appear in North America following the extinction of the non-bird dinosaurs. They differ from other mesonychian families in having less highly modified teeth. Because of their comparatively simpler teeth, the Triisodontids are regarded as basal mesonychids. A recent study found them to be a paraphyletic In taxonomy (general), taxonomy, a group is paraphyletic if it consists of the group's most recent common ancestor, last common ancestor and most of its descendants, excluding a few Monophyly, monophyletic subgroups. The group is said to be pa ... assemblage of stem-mesonychians.Sarah L. Shelley, Thomas E. Wi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dissacus
''Dissacus'' is a genus of extinct carnivorous jackal to coyote-sized mammals within the family Mesonychidae, an early group of hoofed mammals that evolved into hunters and omnivores. Their fossils are found in Paleocene to Early Eocene aged strata in France, Asia and southwest North America, from 66 to 50.3 mya, existing for approximately . Orientation patch analysis of the molar teeth of the North American ''D. praenuntius'' suggests it was an omnivore that ate a lot of meat, not an exclusive meat-eater like a cat or weasel. It shared its environment with more omnivorous mammals of a similar body size. Though they are not ancestral to Carnivora, ''Dissacus'' species may have had similar roles in Paleocene-early Eocene environments as the foxes and other small canids that evolved later: generalized hunters who also ate fruit or other foods, and caught small animals that lived on the ground. The bear-sized ''Ankalagon'' is closely related to ''Dissacus''. Some paleontologists c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pachyaena
''Pachyaena'' (literally, "thick hyena") was a genus of heavily built, relatively short-legged mesonychids, early Cenozoic mammals that evolved before the origin of either modern hoofed animals or carnivores, and combined characteristics similar to both. The genus likely originated from Asia and spread to Europe, and from there to North America across a land bridge in what is now the North Atlantic ocean. Various described species of ''Pachyaena'' ranged in size from a coyote to a bear. However, recent work indicates that ''Pachyaena'' is paraphyletic, with ''P. ossifraga'' being closer to '' Synoplotherium'', '' Harpagolestes'' and ''Mesonyx'' than to ''P. gigantea''. Unlike many mesonychids, ''Pachyaena'' is known from skeletal material in addition to skulls and jaws. Analysis of three wolf- to bear-sized species from the early Eocene of Wyoming (Willwood formation) indicates they all had many adaptations for running, including paraxonic compressed feet with a vestigial first ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Yangtanglestes
''Yantanglestes'' is a genus of small, Chinese mesonychid with slender jaws that first appeared during the Early Paleocene in the Thanetian stage. It was found throughout Asia. It is the oldest known mesonychid. ''Yantanglestes'' became extinct during the Nongshanian division of the Late Paleocene,Missiaen, Pieter. "亚洲早古近纪哺乳动物生物年代学与生物地理学的新认识."古脊椎动物学报 49.1 (2011)paper/ref> and lived sympatrically with its descendant genera, including ''Dissacus'', ''Sinonyx ''Sinonyx'' ("Chinese claw") is a genus of extinct, superficially wolf-like mesonychid mammals from the late Paleocene of China (about 56 million years ago). It is within the family Mesonychidae, and cladistic analysis of a skull of ''Sinonyx'' ...'' and '' Jiangxia''. References External linksScience Mesonychids Paleocene mammals Thanetian life Paleocene mammals of Asia Paleogene China Prehistoric animals of China Fossil taxa described in 1980 Pr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mesonychidae
Mesonychidae (meaning "middle claws") is an extinct family of small to large-sized omnivorous-carnivorous mammals. They were endemic to North America and Eurasia during the Early Paleocene to the Early Oligocene, and were the earliest group of large carnivorous mammals in Asia. They are not closely related to any living mammals. Mesonychid taxonomy has long been disputed and they have captured popular imagination as "wolves on hooves," animals that combine features of both ungulates and carnivores. Skulls and teeth have similar features to early whales, and the family was long thought to be the ancestors of cetaceans. Recent fossil discoveries have overturned this idea; the consensus is that whales are highly derived artiodactyls. Some researchers now consider the family a sister group either to whales or to artiodactyls, close relatives rather than direct ancestors. Other studies define Mesonychia as basal to all ungulates, occupying a position between Perissodactyla and Ferae. I ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ankalagon
''Ankalagon saurognathus'' is an extinct carnivorous mammal of the family Mesonychidae, endemic to North America during the Paleocene epoch (63.3—60.2 mya), existing for approximately . Known from the Paleocene Nacimiento Formation of New Mexico, ''Ankalagon'' is the largest mesonychid known from the Paleocene of North America, and it provides the best evidence for sexual dimorphism in mesonychids. Description The main feature that distinguishes ''A. saurognathus'' from the ancestral ''Dissacus'' species is its size: ''Ankalagon'' grew to be as large as a bear,Paleocene mammals of the world "Carnivores, creodonts and carnivorous ungulates: Mammals become predators" as compared to the coyote or jackal-sized species of ''Dissacus''. In fact, the only North American mesonychids that surpassed ''Ankala ... [...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 Chicxulub impact, an asteroid impact and possibly volcanism, marked the beginning of the Paleocene and killed off 75% of living 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. In the Pal ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Leigh Van Valen
Leigh Van Valen (August 12, 1935 – October 16, 2010) was a U.S. 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 Valen also ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Jackal
Jackals are medium-sized canids native to Africa and Eurasia. While the word "jackal" has historically been used for many canines of the subtribe canina, in modern use it most commonly refers to three species: the closely related black-backed jackal (''Lupulella mesomelas'') and side-striped jackal (''Lupulella adusta'') of sub-Saharan-Africa, and the golden jackal (''Canis aureus'') of south-central Europe and Asia. The African golden wolf (''Canis lupaster'') was also formerly considered as a jackal. While they do not form a monophyletic clade, all jackals are opportunistic omnivores, predators of small to medium-sized animals and proficient scavengers. Their long legs and curved canine teeth are adapted for hunting small mammals, birds, and reptiles, and their large feet and fused leg bones give them a physique well-suited for long-distance running, capable of maintaining speeds of for extended periods of time. Jackals are crepuscular, most active at dawn and dusk. Their ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
New Mexico
) , population_demonym = New Mexican ( es, Neomexicano, Neomejicano, Nuevo Mexicano) , seat = Santa Fe , LargestCity = Albuquerque , LargestMetro = Tiguex , OfficialLang = None , Languages = English, Spanish ( New Mexican), Navajo, Keres, Zuni , Governor = , Lieutenant Governor = , Legislature = New Mexico Legislature , Upperhouse = Senate , Lowerhouse = House of Representatives , Judiciary = New Mexico Supreme Court , Senators = * * , Representative = * * * , postal_code = NM , TradAbbreviation = N.M., N.Mex. , area_rank = 5th , area_total_sq_mi = 121,591 , area_total_km2 = 314,915 , area_land_sq_mi = 121,298 , area_land_km2 = 314,161 , area_water_sq_mi = 292 , area_water_km2 = 757 , area_water_percent = 0.24 , population_as_of = 2020 , population_rank = 36th , 2010Pop = 2,117,522 , population_density_rank = 45th , 2000DensityUS = 17.2 , 2000Density = 6.62 , MedianHouseholdIncome = $51,945 , IncomeRank = 45th , AdmittanceOrder = ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Plantigrade
151px, Portion of a human skeleton, showing plantigrade habit In terrestrial animals, plantigrade locomotion means walking with the toes and metatarsals flat on the ground. It is one of three forms of locomotion adopted by terrestrial mammals. The other options are digitigrade, walking on the toes with the heel and wrist permanently raised, and unguligrade, walking on the nail or nails of the toes (the hoof) with the heel/wrist and the digits permanently raised. The leg of a plantigrade mammal includes the bones of the upper leg (femur/humerus) and lower leg (tibia and fibula/radius and ulna). The leg of a digitigrade mammal also includes the metatarsals/metacarpals, the bones that in a human compose the arch of the foot and the palm of the hand. The leg of an unguligrade mammal also includes the phalanges, the finger and toe bones. Among extinct animals, most early mammals such as pantodonts were plantigrade. A plantigrade foot is the primitive condition for mammals; digit ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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