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Toxodon
''Toxodon'' (meaning "bow tooth" in reference to the curvature of the teeth) is an extinct genus of South American mammals from the Late Miocene to early Holocene epochs (Mayoan to Lujanian in the SALMA classification) (about 11.6 million to 11,000 years ago). It is a member of Notoungulata, one of several now extinct orders of hoofed mammals indigenous to South America distinct from living perissodactyls and artiodactyls. It was among the largest and last members of its order, and was probably the most common large hoofed mammal in South America of its time. Taxonomy ''Toxodon'' was one of the last members of Notoungulata, a group of ungulates that had been part of the fauna of South America since the Paleocene. ''Toxodon'' was a member of Toxodontidae a large bodied group including similar, vaguely rhinoceros like forms. Charles Darwin was one of the first to collect ''Toxodon'' fossils, after paying 18 pence for a ''T. platensis'' skull from a farmer in Urugua ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Toxodon Skeleton
''Toxodon'' (meaning "bow tooth" in reference to the curvature of the teeth) is an extinct genus of South American mammals from the Late Miocene to early Holocene epochs (Mayoan to Lujanian in the SALMA classification) (about 11.6 million to 11,000 years ago). It is a member of Notoungulata, one of several now extinct orders of hoofed mammals indigenous to South America distinct from living perissodactyls and artiodactyls. It was among the largest and last members of its order, and was probably the most common large hoofed mammal in South America of its time. Taxonomy ''Toxodon'' was one of the last members of Notoungulata, a group of ungulates that had been part of the fauna of South America since the Paleocene. ''Toxodon'' was a member of Toxodontidae a large bodied group including similar, vaguely rhinoceros like forms. Charles Darwin was one of the first to collect ''Toxodon'' fossils, after paying 18 pence for a ''T. platensis'' skull from a farmer in Urugua ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
South American Land Mammal Age
The South American land mammal ages (SALMA) establish a geologic timescale for prehistoric South American fauna beginning 64.5 Ma during the Paleocene and continuing through to the Late Pleistocene (0.011 Ma). These periods are referred to as ages, stages, or intervals and were established using geographic place names where fossil materials where obtained.Flynn & Swisher, 1995 The basic unit of measure is the first/last boundary statement. This shows that the first appearance event of one taxon is known to predate the last appearance event of another. If two taxa are found in the same fossil quarry or at the same stratigraphic horizon, then their age-range zones overlap. Background South America was an island continent for much of the Cenozoic, or the "Age of Mammals". As a result, its mammals evolved in their own unique directions, as Australia and Madagascar still have today. Paleogeographic timeline A simplified paleogeographic timeline of South America: * 66 Ma – Sout ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Notoungulata
Notoungulata is an extinct order of mammalian ungulates that inhabited South America from the early Paleocene to the Holocene, living from approximately 61 million to 11,000 years ago. Notoungulates were morphologically diverse, with forms resembling animals as disparate as rabbits and rhinoceroses. Notoungulata are the largest group of South American native ungulates, with over 150 genera in 14 families having been described, divided into two major subgroupings, Typotheria and Toxodontia. Notoungulates first diversified during the Eocene. Their diversity declined during the Late Neogene, with only the large toxodontids persisting until the end of the Pleistocene. Collagen analysis suggests that notoungulates are closely related to litopterns, another group of South American ungulates, and their closest living relatives being perissodactyls (odd-toed ungulates), including rhinoceroses, tapirs and equines. but their relationships to other South American ungulates are uncertain ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Toxodontidae
Toxodontidae is an extinct family of notoungulate mammals, known from the Oligocene to the Holocene (11,000 BP) of South America, with one genus, ''Mixotoxodon'', also known from the Pleistocene of Central America and southwestern North America (Texas).E. Lundelius, et al. 2013. The first occurrence of a toxodont (Mammalia, Notoungulata) in the United States. ''Journal of Vertebrate Paleontology'', Vol 33, No 1, pp. 229–23DOI:10.1080/02724634.2012.711405/ref> They somewhat resembled rhinoceroses, and had teeth with high crowns and open roots, suggesting that they often fed on tough pampas grass. However, isotopic analyses have led to the conclusion that the most recent forms were grazing and browsing generalists. Taxonomy The endemic notoungulate and litoptern ungulates of South America have been shown by studies of collagen and mitochondrial DNA sequences to be a sister group to the perissodactyl Odd-toed ungulates, mammals which constitute the taxonomic order Peris ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Macrauchenia
''Macrauchenia'' ("long llama", based on the now-invalid llama genus, ''Auchenia'', from Greek "big neck") was a large, long-necked and long-limbed, three-toed native South American mammal in the order Litopterna. The genus gives its name to its family, the Macraucheniidae or "robust litopterns". Like other litopterns, it is most closely related to the odd-toed ungulates ( Perissodactyla), from which litopterns diverged approximately 66 million years ago. The oldest fossils in the genus date to the late Miocene, around seven million years ago, and ''M. patachonica'' disappears from the fossil record during the late Pleistocene, around 20,000-10,000 years ago. ''M. patachonica'' is one of the last and best known member of the family and is known primarily from the Luján Formation in Argentina, but is known from localities across southern South America. Another genus of macraucheniid ''Xenorhinotherium'' was present in northeast Brazil and Venezuela during the Late Pleistocene. Th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rhynchippus
''Rhynchippus'' ("Snout Horse") is an extinct genus of notoungulate mammals from the Late Oligocene ( Deseadan in the SALMA classification) of South America. The genus was first described by Florentino Ameghino in 1897 and the type species is ''R. equinus'', with lectotype MACN A 52–31. Fossils of ''Rhynchippus'' have been found in the Agua de la Piedra and Sarmiento Formations of Argentina, the Salla and Petaca Formations of Bolivia, the Tremembé Formation of Brazil,''Rhynchippus'' at Fossilworks.org and the Moquegua Formation of |
Litoptern
Litopterna (from grc, λῑτή πτέρνα "smooth heel") is an extinct order of fossil hoofed mammals from the Cenozoic era. The order is one of the five great orders of South American ungulates that were endemic to the continent, until the Great American Biotic Interchange brought new ungulate species. Like other endemic South American mammals, their relationship to other mammal groups had long been unclear, but recent genetic and proteomic evidence indicates that their closest living relatives are Perissodactyls (odd-toed ungulates) including horses, rhinoceros, and tapirs, and that litopterns are closely related to notoungulates, another widespread group of South American ungulates. There were two major groups of litopterns: Proterotheriidae and Macraucheniidae. Proterotheriids were medium to large animals that evolved adaptations for fast running, and occupied a variety of niches that elsewhere were filled by animals such as goats and antelopes, mouse deer, and hors ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Perissodactyl
Odd-toed ungulates, mammals which constitute the taxonomic order Perissodactyla (, ), are animals—ungulates—who have reduced the weight-bearing toes to three (rhinoceroses and tapirs, with tapirs still using four toes on the front legs) or one (equines, third toe) of the five original toes. The non-weight-bearing toes are either present, absent, vestigial, or positioned posteriorly. By contrast, the even-toed ungulates bear most of their weight equally on four or two (an even number) of the five toes: their third and fourth toes. Another difference between the two is that odd-toed ungulates digest plant cellulose in their intestines rather than in one or more stomach chambers as even-toed ungulates, with the exception of Suina, do. The order includes about 17 species divided into three families: Equidae (horses, asses, and zebras), Rhinocerotidae (rhinoceroses), and Tapiridae (tapirs). Despite their very different appearances, they were recognized as related families ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Charles Darwin
Charles Robert Darwin ( ; 12 February 1809 – 19 April 1882) was an English naturalist, geologist, and biologist, widely known for his contributions to evolutionary biology. His proposition that all species of life have descended from a common ancestor is now generally accepted and considered a fundamental concept in science. In a joint publication with Alfred Russel Wallace, he introduced his scientific theory that this branching pattern of evolution resulted from a process he called natural selection, in which the struggle for existence has a similar effect to the artificial selection involved in selective breeding. Darwin has been described as one of the most influential figures in human history and was honoured by burial in Westminster Abbey. Darwin's early interest in nature led him to neglect his medical education at the University of Edinburgh; instead, he helped to investigate marine invertebrates. His studies at the University of Cambridge's Christ's ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Collagen
Collagen () is the main structural protein in the extracellular matrix found in the body's various connective tissues. As the main component of connective tissue, it is the most abundant protein in mammals, making up from 25% to 35% of the whole-body protein content. Collagen consists of amino acids bound together to form a triple helix of elongated fibril known as a collagen helix. It is mostly found in connective tissue such as cartilage, bones, tendons, ligaments, and skin. Depending upon the degree of mineralization, collagen tissues may be rigid (bone) or compliant (tendon) or have a gradient from rigid to compliant (cartilage). Collagen is also abundant in corneas, blood vessels, the gut, intervertebral discs, and the dentin in teeth. In muscle tissue, it serves as a major component of the endomysium. Collagen constitutes one to two percent of muscle tissue and accounts for 6% of the weight of the skeletal muscle tissue. The fibroblast is the most common ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sister Group
In phylogenetics, a sister group or sister taxon, also called an adelphotaxon, comprises the closest relative(s) of another given unit in an evolutionary tree. Definition The expression is most easily illustrated by a cladogram: Taxon A and taxon B are sister groups to each other. Taxa A and B, together with any other extant or extinct descendants of their most recent common ancestor (MRCA), form a monophyletic group, the clade AB. Clade AB and taxon C are also sister groups. Taxa A, B, and C, together with all other descendants of their MRCA form the clade ABC. The whole clade ABC is itself a subtree of a larger tree which offers yet more sister group relationships, both among the leaves and among larger, more deeply rooted clades. The tree structure shown connects through its root to the rest of the universal tree of life. In cladistic standards, taxa A, B, and C may represent specimens, species, genera, or any other taxonomic units. If A and B are at the same taxo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rodent
Rodents (from Latin , 'to gnaw') are mammals of the order Rodentia (), which are characterized by a single pair of continuously growing incisors in each of the upper and lower jaws. About 40% of all mammal species are rodents. They are native to all major land masses except for New Zealand, Antarctica, and several oceanic islands, though they have subsequently been introduced to most of these land masses by human activity. Rodents are extremely diverse in their ecology and lifestyles and can be found in almost every terrestrial habitat, including human-made environments. Species can be arboreal, fossorial (burrowing), saltatorial/richochetal (leaping on their hind legs), or semiaquatic. However, all rodents share several morphological features, including having only a single upper and lower pair of ever-growing incisors. Well-known rodents include mice, rats, squirrels, prairie dogs, porcupines, beavers, guinea pigs, and hamsters. Rabbits, hares, and pikas, wh ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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