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Purgatorius
''Purgatorius'' is a genus of seven extinct eutherian species typically believed to be the earliest example of a primate or a proto-primate, a primatomorph precursor to the Plesiadapiformes, dating to as old as 66 million years ago. The first remains (''P. unio'' and ''P. ceratops'') were reported in 1965, from what is now eastern Montana's Tullock Formation (early Paleocene, Puercan), specifically at Purgatory Hill (hence the animal's name) in deposits believed to be about 63 million years old, and at Harbicht Hill in the lower Paleocene section of the Hell Creek Formation. Both locations are in McCone County. They have also been found in the Ravenscrag Formation and widely discovered in the early Paleocene Bug Creek Group, along with leptictids. These deposits were once thought to be late Cretaceous, but it is now clear that they are Paleocene channels with time-averaged fossil assemblages. It is thought to have been rat-sized ( long and 1.3 ounces (about 37 grams)) and a diur ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Purgatorius PNAS
''Purgatorius'' is a genus of seven extinct eutherian species typically believed to be the earliest example of a primate or a proto-primate, a primatomorph precursor to the Plesiadapiformes, dating to as old as 66 million years ago. The first remains (''P. unio'' and ''P. ceratops'') were reported in 1965, from what is now eastern Montana's Tullock Formation (early Paleocene, Puercan), specifically at Purgatory Hill (hence the animal's name) in deposits believed to be about 63 million years old, and at Harbicht Hill in the lower Paleocene section of the Hell Creek Formation. Both locations are in McCone County. They have also been found in the Ravenscrag Formation and widely discovered in the early Paleocene Bug Creek Group, along with leptictids. These deposits were once thought to be late Cretaceous, but it is now clear that they are Paleocene channels with time-averaged fossil assemblages. It is thought to have been rat-sized ( long and 1.3 ounces (about 37 grams)) and a diurn ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Plesiadapiformes
Plesiadapiformes (" Adapid-like" or "near Adapiformes") is a group of Primates, a sister of the Dermoptera. While none of the groups normally directly assigned to this group survived, the group appears actually not to be literally extinct (in the sense of having no living descendants) as the remaining primates (the crown primates or "Euprimates") appear to be derived Plesiadapiformes, as a sister of e.g. the Carpolestidae. The term Plesiadapiformes may still be used for all primates which are not crown primates, but this usage is paraphyletic. When the crown primates are cladistically granted, it becomes an obsolete junior synonym to primates. ''Purgatorius'' is believed to be a basal Plesiadapiformes. Plesiadapiformes first appear in the fossil record between 65 and 55 million years ago, although many were extinct by the beginning of the Eocene. They may have been the first mammals to have finger nails in place of claws. In 1990, K.C. Beard attempted to link the Plesiadapiforme ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Plesiadapiforms
Plesiadapiformes (" Adapid-like" or "near Adapiformes") is a group of Primates, a sister of the Dermoptera. While none of the groups normally directly assigned to this group survived, the group appears actually not to be literally extinct (in the sense of having no living descendants) as the remaining primates (the crown primates or "Euprimates") appear to be derived Plesiadapiformes, as a sister of e.g. the Carpolestidae. The term Plesiadapiformes may still be used for all primates which are not crown primates, but this usage is paraphyletic. When the crown primates are cladistically granted, it becomes an obsolete junior synonym to primates. ''Purgatorius'' is believed to be a basal Plesiadapiformes. Plesiadapiformes first appear in the fossil record between 65 and 55 million years ago, although many were extinct by the beginning of the Eocene. They may have been the first mammals to have finger nails in place of claws. In 1990, K.C. Beard attempted to link the Plesiadapiforme ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Primate
Primates are a diverse order of mammals. They are divided into the strepsirrhines, which include the lemurs, galagos, and lorisids, and the haplorhines, which include the tarsiers and the simians (monkeys and apes, the latter including humans). Primates arose 85–55 million years ago first from small terrestrial mammals, which adapted to living in the trees of tropical forests: many primate characteristics represent adaptations to life in this challenging environment, including large brains, visual acuity, color vision, a shoulder girdle allowing a large degree of movement in the shoulder joint, and dextrous hands. Primates range in size from Madame Berthe's mouse lemur, which weighs , to the eastern gorilla, weighing over . There are 376–524 species of living primates, depending on which classification is used. New primate species continue to be discovered: over 25 species were described in the 2000s, 36 in the 2010s, and three in the 2020s. Primates have large bra ... [...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] |
Primates
Primates are a diverse order of mammals. They are divided into the strepsirrhines, which include the lemurs, galagos, and lorisids, and the haplorhines, which include the tarsiers and the simians (monkeys and apes, the latter including humans). Primates arose 85–55 million years ago first from small terrestrial mammals, which adapted to living in the trees of tropical forests: many primate characteristics represent adaptations to life in this challenging environment, including large brains, visual acuity, color vision, a shoulder girdle allowing a large degree of movement in the shoulder joint, and dextrous hands. Primates range in size from Madame Berthe's mouse lemur, which weighs , to the eastern gorilla, weighing over . There are 376–524 species of living primates, depending on which classification is used. New primate species continue to be discovered: over 25 species were described in the 2000s, 36 in the 2010s, and three in the 2020s. Primates have large bra ... [...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] |
Palaeocene
The Paleocene, ( ) or Palaeocene, is a geological epoch that lasted from about 66 to 56 million years ago (mya). It is the first epoch of the Paleogene Period in the modern Cenozoic 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 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 Paleocene, the continents of the Northern Hemisphere were still connected via ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Protungulatum
''Protungulatum'' ('first ungulate') is a extinct genus of pan-euungulate mammals within extinct family Protungulatidae, and also one of the earliest known placental mammals in the fossil record, that lived in North America from the Late Cretaceous to early Paleocene.Maeva Orliac (2016."The inner ear of ''Protungulatum'' (Pan-Euungulata, Mammalia)"Journal of Mammalian Evolution 23(4) Fossils of this genus were first found in the Bug Creek Anthills in northeastern Montana. The Bug Creek Anthills were initially believed to be Late Cretaceous (latest Maastrichtian) because of the presence of the remains of non-avian dinosaurs and common Cretaceous mammals, but these were later shown to have been reworked from Late Cretaceous strata, and consequently the Bug Creek Anthills are currently believed to be Early Paleocene (Puercan) in age. Remains from the Ravenscrag Formation of Saskatchewan, Canada have been assigned to ''Protungulatum donnae''. These remains may also be Cretaceous ... [...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] |
Tree Shrew
The treeshrews (or tree shrews or banxrings) are small mammals native to the tropical forests of South and Southeast Asia. They make up the entire order Scandentia, which split into two families: the Tupaiidae (19 species, "ordinary" treeshrews), and the Ptilocercidae (one species, the pen-tailed treeshrew). Though called 'treeshrews', and despite having previously been classified in Insectivora, they are not true shrews, and not all species live in trees. They are omnivores; among other things, treeshrews eat fruit. Treeshrews have a higher brain to body mass ratio than any other mammal, including humans, but high ratios are not uncommon for animals weighing less than . Among orders of mammals, treeshrews are closely related to primates, and have been used as an alternative to primates in experimental studies of myopia, psychosocial stress, and hepatitis. Name The name '' Tupaia'' is derived from ''tupai'', the Indonesian word for squirrel, and was provided by Sir Stamford ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cretaceous Mammals
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 by the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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