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Australosphenida
The Australosphenida are a proposed infraclass of mammals within subclass Yinotheria. Today, there are only five surviving species, which live in Australia and New Guinea, but fossils have been found in Madagascar and Argentina. The surviving species consist of the platypus and four species of echidna. Contrary to other known crown mammals, they retained postdentary bones as shown by the presence of a postdentary trough. The extant members (monotremes) developed the mammalian middle ear independently. Taxonomy This grouping includes the following taxa: *Monotremata, divided into the families Ornithorhynchidae (platypus), Steropodontidae and Tachyglossidae (echidnas) and the genus ''Kryoryctes'' *†Henosferidae, including the genera ''Ambondro'', ''Asfaltomylos'', and ''Henosferus'' from the Jurassic of Argentina and Madagascar. *†Ausktribosphenidae, including the genera ''Ausktribosphenos'', ''Bishops'' from the Middle Jurassic to Lower Cretaceous of Australia. *†Kollikodont ...
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Ambondro (genus)
''Ambondro mahabo'' is a mammal from the Middle Jurassic (Bathonian) Isalo III Formation (about 167 million years ago) of Madagascar. The only described species of the genus ''Ambondro'', it is known from a fragmentary lower jaw with three teeth, interpreted as the last premolar and the first two molars. The premolar consists of a central cusp with one or two smaller cusps and a cingulum (shelf) on the inner, or lingual, side of the tooth. The molars also have such a lingual cingulum. They consist of two groups of cusps: a trigonid of three cusps at the front and a talonid with a main cusp, a smaller cusp, and a crest at the back. Features of the talonid suggest that ''Ambondro'' had tribosphenic molars, the basic arrangement of molar features also present in marsupial and placental mammals. It is the oldest known mammal with putatively tribosphenic teeth; at the time of its discovery it antedated the second oldest example by about 25 million years. Upon its description in 1999, ' ...
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Yinotheria
Yinotheria is a proposed basal subclass clade of crown mammals that contains a few fossils of the Mesozoic and the extant monotremes. Today, there are only five surviving species, which live in Australia and New Guinea, but fossils have been found in England, China, Russia, Madagascar and Argentina. The surviving species consist of the platypus and four species of echidna. Contrary to other known crown mammals, they retained postdentary bones as shown by the presence of a postdentary trough. The extant members (monotremes) developed the mammalian middle ear independently. Evolutionary history According to genetic studies, Yinotheria diverged from other mammals around 220 to 210 million years ago, at some point in the Triassic or Early Jurassic.http://timetree.org/pdf/Madsen2009Chap68.pdf The oldest-known fossils are a bit younger, dating around 168 to 163 million years in the Middle Jurassic. These fossils are the genera ''Pseudotribos'' of China, ''Shuotherium'' of both China and E ...
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Asfaltomylos
''Asfaltomylos'' is an extinct genus of the primitive mammal subclass Australosphenida from the middle Jurassic of Argentina. The type and only species is ''Asfaltomylos patagonicus'', recovered from and named after the Cañadón Asfalto Formation, Cañadón Asfalto Basin of Chubut Province, Patagonia.''Asfaltomylos''
at Fossilworks.org


See also


* ''Argentoconodon'' * ''Condorodon'' * ''
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Ausktribosphenidae
Ausktribosphenidae is a family of mammals from the Early Cretaceous of Australia that are closely related to monotremes. Classification and taxonomy Ausktribosphenidae is closely related to monotremes and hence the two form the yinotherian clade Australosphenida. It includes two species, ''Ausktribosphenos nyktos'' and ''Bishops whitmorei'', both of which are known only from skull and jaw fragments. Morphology Like other Australosphenida, ausktribosphenids have tribosphenic molars. Distribution Given that Ausktribosphenidae has been found in Early Cretaceous deposits in Australia, its occurrence has ramifications for knowledge of early monotreme paleobiogeography because Australia was connected only to Antarctica, and placentals originated in the northern hemisphere and were confined to it until continental drift formed land connections from North America to South America, from Asia to Africa and from Asia to India. The late Cretaceous map shows how the southern continents are sep ...
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Ausktribosphenos
''Ausktribosphenos'' is an extinct genus of mammals from Early Cretaceous of Australia. The only recorded species, ''Ausktribosphenos nyktos'', was found on Flat Rocks, Victoria. References * Category:Cretaceous mammals of Australia Category:Australosphenida Category:Fossil taxa described in 1997 Category:Prehistoric mammal genera {{Cretaceous-animal-stub ...
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Bishops (genus)
''Bishops'' is an extinct genus of mammals from Early Cretaceous of Australia. The only recorded species, ''Bishops whitmorei'', was found on Flat Rocks, Wonthaggi Formation, Victoria. The genus was named in honour of the Dr Barry Bishop, the former Chairman of the Committee for Research and Exploration, National Geographic Society. References * Rich, T. H.; Flannery, T. F.; Trusler, P.; Kool, L.; van Klaveren, N. A. & Vickers-Rich, P. 2001. "A second tribosphenic mammal from the Mesozoic of Australia." ''Records of the Queen Victoria Museum'' 110: 1–9. Category:Cretaceous mammals of Australia Category:Australosphenida Category:Extinct mammals of Australia Category:Prehistoric mammal genera {{Cretaceous-animal-stub ...
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Jurassic
The Jurassic ( ) is a geologic period and stratigraphic system that spanned from the end of the Triassic period million years ago (Mya) to the beginning of the Cretaceous period approximately Mya. The Jurassic constitutes the middle period of the Mesozoic Era. The Jurassic is named after the Jura Mountains in the European Alps, where limestone strata from the period were first identified. The start of the Jurassic was marked by the major Triassic–Jurassic extinction event, associated with the eruption of the Central Atlantic Magmatic Province. The beginning of the Toarcian stage around 183 million years ago is marked by an extinction event associated with widespread oceanic anoxia, ocean acidification and elevated temperatures likely caused by the eruption of the Karoo-Ferrar large igneous provinces. The end of the Jurassic has no clear boundary with the following Cretaceous, and is the only boundary between geological periods to remain formally undefined. By the beginning of t ...
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Henosferus
''Henosferus'' is an extinct genus of australosphenidan mammal from Middle Jurassic of Argentina. The only recorded species, ''Henosferus molus'', was found in the Cañadón Asfalto Formation of the Cañadón Asfalto Basin in Chubut Province, Patagonia.Rougier, G. W., Martinelli, A. G., Forasiepi, A. M. & Novacek, M. J. 2007. ''New Jurassic mammals from Patagonia, Argentina: A reappraisal of australosphenidan morphology and interrelationships''. ''American Museum Novitates'' 3566: 1-54. References Category:Australosphenida Category:Bathonian life Category:Jurassic mammals of South America Category:Middle Jurassic tetrapods of South America Category:Jurassic Argentina Category:Fossils of Argentina Category:Cañadón Asfalto Formation Category:Fossil taxa described in 2007 Category:Prehistoric mammal genera {{paleo-mammal-stub ...
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Molar (tooth)
The molars or molar teeth are large, flat teeth at the back of the mouth. They are more developed in mammals. They are used primarily to grind food during chewing. The name molar derives from Latin, ''molaris dens'', meaning "millstone tooth", from ''mola'', millstone and ''dens'', tooth. Molars show a great deal of diversity in size and shape across mammal groups. The third molar of humans is a vestigial organ, as it has lost its original function. Human anatomy In humans, the molar teeth have either four or five cusps. Adult humans have 12 molars, in four groups of three at the back of the mouth. The third, rearmost molar in each group is called a wisdom tooth. It is the last tooth to appear, breaking through the front of the gum at about the age of 20, although this varies from individual to individual. Race can also affect the age at which this occurs, with statistical variations between groups. In some cases, it may not even erupt at all. The human mouth contains upper (max ...
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Henosferidae
Henosferidae (also spelled "Henospheridae") is an extinct family of Australosphenida, native to Gondwana during the Middle Jurassic. Its defined as a clade including the most recent common ancestor of ''Henosferus'' and ''Asfaltomylos'' and all its descendants. References * Averianov, A. O. & Lopatin, A. V., '"Phylogeny of truconodonts and symmetrodonts and the origin of extinct mammals"', Dokl Biol Sci 436:32-35. * Rougier, G. W., Martinelli, A. G., Forasiepi, A. M. & Novacek, M. J. 2007. New Jurassic mammals from Patagonia, Argentina: A reappraisal of australosphenidan morphology and interrelationships. ''American Museum Novitates'' 3566: 1-54. Category:Jurassic mammals Category:Prehistoric mammal families {{paleo-mammal-stub ...
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Linnaean Taxonomy
Linnaean taxonomy can mean either of two related concepts: # the particular form of biological classification (taxonomy) set up by Carl Linnaeus, as set forth in his ''Systema Naturae'' (1735) and subsequent works. In the taxonomy of Linnaeus there are three kingdoms, divided into ''classes'', and they, in turn, into ''orders'', ''genera'' (singular: ''genus''), and ''species'' (singular: ''species''), with an additional rank lower than species. # a term for rank-based classification of organisms, in general. That is, taxonomy in the traditional sense of the word: rank-based scientific classification. This term is especially used as opposed to cladistic systematics, which groups organisms into clades. It is attributed to Linnaeus, although he neither invented the concept of ranked classification (it goes back to Plato and Aristotle) nor gave it its present form. In fact, it does not have an exact present form, as "Linnaean taxonomy" as such does not really exist: it is a collectiv ...
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Cladotheria
Cladotheria is a group (legion) of mammals that includes the ancestor of Dryolestida, Amphitheriida, Peramuridae and Zatheria (living therians plus all of its ancestors). Phylogeny Below is a cladogram from Rowe (1988) and McKenna and Bell (1997) showing one hypothesis of mammal relationships: Further reading Zofia Kielan-Jaworowska, Richard L. Cifelli, and Zhe-Xi Luo, ''Mammals from the Age of Dinosaurs: Origins, Evolution, and Structure'' (New York: Columbia University Press, 2004), 14, 531. References External links MESOZOIC MAMMALS; Stem zatherians, zatherians & Peramuridae, an internet directory Category:Extant Middle Jurassic first appearances Category:Taxa described in 1975 {{paleo-mammal-stub ...
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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 nearly 80 million years, it is the longest geological period of the entire Phanerozoic, almost surpassing the Ediacaran & Cryogenian in size. 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 t ...
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Genus
Genus (plural genera) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses, in biology. In the hierarchy of biological classification, genus comes above species and below family. In binomial nomenclature, the genus name forms the first part of the binomial species name for each species within the genus. :E.g. ''Panthera leo'' (lion) and ''Panthera onca'' (jaguar) are two species within the genus ''Panthera''. ''Panthera'' is a genus within the family Felidae. The composition of a genus is determined by taxonomists. The standards for genus classification are not strictly codified, so different authorities often produce different classifications for genera. There are some general practices used, however, including the idea that a newly defined genus should fulfill these three criteria to be descriptively useful: # monophyly – all descendants of an ancestral taxon are grouped together (i.e. phylogenetic analysis should clearly ...
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