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Mesozoic Mammals Of Madagascar
Several mammals are known from the Mesozoic of Madagascar. The Bathonian (middle Jurassic) '' Ambondro'', known from a piece of jaw with three teeth, is the earliest known mammal with molars showing the modern, tribosphenic pattern that is characteristic of marsupial and placental mammals. Interpretations of its affinities have differed; one proposal places it in a group known as Australosphenida with other Mesozoic tribosphenic mammals from the southern continents (Gondwana) as well as the monotremes, while others favor closer affinities with northern (Laurasian) tribosphenic mammals or specifically with placentals. At least five species are known from the Maastrichtian (late Cretaceous), including a yet undescribed species known from a nearly complete skeleton that may represent a completely new group of mammals. The gondwanathere ''Lavanify'', known from two teeth, is most closely related to other gondwanatheres found in India and Argentina. Two other teeth may represent anothe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mammal
Mammals () are a group of vertebrate animals constituting the class (biology), class Mammalia (), characterized by the presence of mammary glands which in Female#Mammalian female, females produce milk for feeding (nursing) their young, a neocortex (a region of the brain), fur or hair, and three ossicles, middle ear bones. These characteristics distinguish them from reptiles (including birds) from which they Genetic divergence, diverged in the Carboniferous, over 300 million years ago. Around 6,400 extant taxon, extant species of mammals have been described divided into 29 Order (biology), orders. The largest Order (biology), orders, in terms of number of species, are the rodents, bats, and Eulipotyphla (hedgehogs, Mole (animal), moles, shrews, and others). The next three are the Primates (including humans, apes, monkeys, and others), the Artiodactyla (cetaceans and even-toed ungulates), and the Carnivora (cats, dogs, pinniped, seals, and others). In terms of cladistic ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lavanify
''Lavanify'' is a mammalian genus from the late Cretaceous (probably Maastrichtian, about 71 to 66 million years ago) of Madagascar. The only species, ''L. miolaka'', is known from two isolated teeth, one of which is damaged. The teeth were collected in 1995–1996 and described in 1997. The animal is classified as a member of Gondwanatheria, an enigmatic extinct group with unclear phylogenetic relationships, and within Gondwanatheria as a member of the family Sudamericidae. ''Lavanify'' is most closely related to the Indian '' Bharattherium''; the South American '' Sudamerica'' and ''Gondwanatherium'' are more distantly related. Gondwanatheres probably ate hard plant material. ''Lavanify'' had high- crowned, curved teeth. One of the two teeth is 11.2 mm high and shows a deep furrow and, is centered laterally in the crown, a V-shaped area that consists of dentine. The other, damaged, tooth is 9.8 mm high and has at least one deep cavity (infundibulum). Charac ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dinosaur
Dinosaurs are a diverse group of reptiles of the clade Dinosauria. They first appeared during the Triassic period, between 243 and 233.23 million years ago (mya), although the exact origin and timing of the evolution of dinosaurs is the subject of active research. They became the dominant terrestrial vertebrates after the Triassic–Jurassic extinction event 201.3 mya; their dominance continued throughout the Jurassic and Cretaceous periods. The fossil record shows that birds are feathered dinosaurs, having evolved from earlier theropods during the Late Jurassic epoch, and are the only dinosaur lineage known to have survived the Cretaceous–Paleogene extinction event approximately 66 mya. Dinosaurs can therefore be divided into avian dinosaurs—birds—and the extinct non-avian dinosaurs, which are all dinosaurs other than birds. Dinosaurs are varied from taxonomic, morphological and ecological standpoints. Birds, at over 10,700 living species ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bishops Whitmorei
''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 Dr Barry Bishop, the former Chairman of the Committee for Research and Exploration, National Geographic Society The National Geographic Society (NGS), headquartered in Washington, D.C., United States, is one of the largest non-profit scientific and educational organizations in the world. Founded in 1888, its interests include geography, archaeology, .... References Further reading * 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. Cretaceous mammals of Australia Australosphenida Extinct mammals of Australia {{cretaceous-mammal-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Henosferus
''Henosferus'' is an extinct genus of australosphenidan mammal from Lower Jurassic of Argentina. The only recorded species, ''Henosferus molus'', was found in the Cañadón Asfalto Formation of the Cañadón Asfalto Basin in Chubut Province Chubut ( es, Provincia del Chubut, ; cy, Talaith Chubut) is a province in southern Argentina, situated between the 42nd parallel south (the border with Río Negro Province), the 46th parallel south (bordering Santa Cruz Province), the Andes ran ..., 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. The species is known only from 3 lower jaws and possibly an upper molar. References Australosphenida Bathonian life Jurassic mammals of South America Middle Jurassic tetrapods of South America Jurassic Argentina Fossils of Argentina C ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Asfaltomylos
''Asfaltomylos'' is an extinct genus of the primitive mammal subclass Australosphenida from the 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. at .org See also * '''' * '''' * '' |
Boreosphenida
Tribosphenida is a group (infralegion) of mammals that includes the ancestor of ''Hypomylos'', Aegialodontia and Theria (the last common ancestor of marsupials and placentals plus all of its descendants). Its current definition is more or less synonymous with Boreosphenida. Characteristics Tribosphenid mammals were originally grouped on the basis of triangular or V-shaped ( tribosphenic) molars. Since then, other unrelated mammal groups have been found to have tribosphenic molars, such as the australosphenidans (a group that includes the still extant monotremes), suggesting that as a synapomorphy this is fundamentally useless as it evolved multiple times among mammals. However, a clade between the aforementioned groups, the "true Tribosphenida" or Boreosphenida, is still identifiable, united by characteristics such as the lack of a mesial cingulid and of a triangulated trigonid on the last premolar. They are also united by postcranial features such as the presence of a mo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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 Victoria most commonly refers to: * Victoria (Australia), a state of the Commonwealth of Australia * Victoria, British Columbia, provincial capital of British Columbia, Canada * Victoria (mythology), Roman goddess of Victory * Victoria, Seychelle .... References Cretaceous mammals of Australia Australosphenida Fossil taxa described in 1997 Prehistoric mammal genera {{cretaceous-mammal-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Clade
A clade (), also known as a monophyletic group or natural group, is a group of organisms that are monophyletic – that is, composed of a common ancestor and all its lineal descendants – on a phylogenetic tree. Rather than the English term, the equivalent Latin term ''cladus'' (plural ''cladi'') is often used in taxonomical literature. The common ancestor may be an individual, a population, or a species (extinct or extant). Clades are nested, one in another, as each branch in turn splits into smaller branches. These splits reflect evolutionary history as populations diverged and evolved independently. Clades are termed monophyletic (Greek: "one clan") groups. Over the last few decades, the cladistic approach has revolutionized biological classification and revealed surprising evolutionary relationships among organisms. Increasingly, taxonomists try to avoid naming taxa that are not clades; that is, taxa that are not monophyletic. Some of the relationships between org ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Zhe-Xi Luo
Zhe-Xi Luo (Chinese 骆泽喜; pinyin: Luò Zéxǐ) is an American paleontologist of Chinese origin, specializing in vertebrate paleontology, particularly mammal evolution, morphology, and systematics. Background Born in China in 1958, he came to the United States in 1982 as one of the first Chinese students. Under the Sino-US agreement, students were expected to return to their homeland after graduation, but after the 1989 Tiananmen Square massacre, US President George H. W. Bush agreed that around 80,000 Chinese students would remain in the United States. Zhe-Xi Luo and his wife were in this group. Luo gained his Bachelor's in Geology, Stratigraphy and Paleontology in 1982 from Nanjing University's Department of Geology, before completing his PhD in Paleontology at the University of California at Berkeley, Museum of Paleontology in 1989. He then completed a postdoctoral fellowship in Mammalian Evolutionary Morphology at Harvard University, Museum of Comparative Zoology in 1 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Premolar
The premolars, also called premolar teeth, or bicuspids, are transitional teeth located between the canine and molar teeth. In humans, there are two premolars per quadrant in the permanent set of teeth, making eight premolars total in the mouth. They have at least two cusps. Premolars can be considered transitional teeth during chewing, or mastication. They have properties of both the canines, that lie anterior and molars that lie posterior, and so food can be transferred from the canines to the premolars and finally to the molars for grinding, instead of directly from the canines to the molars. Human anatomy The premolars in humans are the maxillary first premolar, maxillary second premolar, mandibular first premolar, and the mandibular second premolar. Premolar teeth by definition are permanent teeth distal to the canines, preceded by deciduous molars. Morphology There is always one large buccal cusp, especially so in the mandibular first premolar. The lower sec ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ambondro Mahabo
''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 19 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
