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Deltatheroida
Deltatheroida is an extinct group of basal metatherians that were distantly related to modern marsupials. The majority of known members of the group lived in the Cretaceous; one species, '' Gurbanodelta kara'', is known from the late Paleocene ( Gashatan) of China. Their fossils are restricted to Central Asia and North America. This order can be defined as all metatherians closer to '' Deltatheridium'' than to Marsupialia. These mammals possessed primitive tritubercular (three-cusped) lower molars that were not tribosphenic. This is awkward because tribosphenic molars are commonly found in most therian mammals (there exist some exceptions such as anteaters and some whales, which have no teeth at all). When they were first identified in the 1920s, they were believed to be placentals and possible ancestors of the "creodonts" (a polyphyletic group of extinct carnivorous mammals from the Paleogene and Miocene), but this was later disproven. Nonetheless, deltatheroideans do conver ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Metatheria
Metatheria is a mammalian clade that includes all mammals more closely related to marsupials than to placentals. First proposed by Thomas Henry Huxley in 1880, it is a more inclusive group than the marsupials; it contains all marsupials as well as many extinct non-marsupial relatives. There are three extant subclasses of mammals, one being metatherians: # monotremes: egg laying mammals like the platypus and the echidna, #metatheria: marsupials, which includes three American orders ( Didelphimorphia, Paucituberculata and Microbiotheria) and four Australasian orders ( Notoryctemorphia, Dasyuromorphia, Peramelemorphia and Diprotodontia), and the #eutherians: placental mammals, consisting of four superorders divided into 21 orders. Metatherians belong to a subgroup of the northern tribosphenic mammal clade or Boreosphenida. They differ from all other mammals in certain morphologies like their dental formula, which includes about five upper and four lower incisors, a canine ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tsagandelta
''Tsagandelta'' (meaning "white crest") is a genus of deltatheroidean therian mammal that lived in Asia during the Late Cretaceous. Distantly related to modern marsupials, it is part of Deltatheroida, a lineage of carnivorous metatherians common in the Cretaceous of Asia and among the most successful non-theropod carnivores of the region. It represents the first known mammal from the Bayan Shireh Formation. Discovery and naming The holotype was first discovered and collected in 2002 during the field expedition conducted by the Mongolian Academy of Sciences and the American Museum of Natural History, the specimen only preserved a partial left dentary. It was discovered on the outcrops at the Tsagan Tsonj locality in the Bayan Shireh Formation, the age is estimated to be around 102 million to 86 million years ago, between the Cenomanian and Santonian stages of the Late Cretaceous epoch. The generic name, ''Tsagandelta'', is derived from the Mongolian цагаан (tsagaan, meaning ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Oklatheridium
''Oklatheridium'' is an extinct genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial n ... of deltatheroidan.B. M. Davis, R. L. Cifelli, and Z. Kielan-Jaworowska. 2008. 1. Earliest Evidence of Deltatheroida (Mammalia: Metatheria) from the Early Cretaceous of North America. Mammalian Evolutionary Morphology: A Tribute to Frederick S. Szalay 3-24 References Prehistoric metatherians Cretaceous mammals of North America Fossil taxa described in 2008 Prehistoric mammal genera {{cretaceous-mammal-stub ... [...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 Ear ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pappotheriidae
''Pappotherium'' is an extinct genus of mammals from the Albian (early Cretaceous) of Texas, US, known from a fossilized maxilla fragment bearing two tribosphenic molars, discovered within the Glen Rose Formation near Decatur, Wise County, Texas. The fossil was discovered by Bob H. Slaughter within some deposits dating back to 112.6 – 109 million years ago. On the basis of the morphology of the molars' cusps, in 1965 Slaughter established the new genus ''Pappotherium'' and the new species ''P. pattersoni''; he also created an apposite family, Pappotheriidae. Both this family and the genus are nowadays still monotypic. Slaughter argued that ''Pappotherium'' should have been a basal form close to the metatherian- eutherian divergence point; this mammal likely was an arboreal insectivore. Etymologically speaking, the name ''Pappotherium'' is a compound of the Latin words ''pappus'' (from ancient Greek πάππος, ''páppos'', “grandfather”) and ''therium'' (from ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Deltatheridiidae
Deltatheridiidae is an extinct family of basal carnivorous metatherians that lived in the Cretaceous and were closely related to marsupials. Their fossils are restricted to Central Asia ( Mongolia and Uzbekistan) and North America ( United States - Oklahoma, Texas, Utah, Wyoming). They mostly disappeared in the KT event, but a ghost lineage, currently represented by '' Gurbanodelta'', survived until the late Paleocene by decreasing in size and becoming insectivorous. The family consist in six genera:Xijun Ni; Qiang Li; Thomas A. Stidham; Lüzhou Li; Xiaoyu Lu; Jin Meng (2016). "A late Paleocene probable metatherian (?deltatheroidan) survivor of the Cretaceous mass extinction". Scientific Reports. 6: Article number 38547. . *'' Atokatheridium'' *'' Deltatheridium'' *'' Deltatheroides'' *'' Gurbanodelta'' *'' Lotheridium'' *''Oklatheridium'' *'' Nanocuris'' *''Sulestes'' *''Tsagandelta ''Tsagandelta'' (meaning "white crest") is a genus of deltatheroidean theria ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Atokatheridium
''Atokatheridium'' is an extinct genus of Deltatheridiidae Deltatheridiidae is an extinct family of basal carnivorous metatherians that lived in the Cretaceous and were closely related to marsupials. Their fossils are restricted to Central Asia ( Mongolia and Uzbekistan) and North America ( United S ... from Cretaceous of United States.Z. Kielan-Jaworowska and R. L. Cifelli. 2001. Primitive boreosphenidan mammal (?Deltatheroida) from the Early Cretaceous of Oklahoma. Acta Palaeontologica Polonica 46(3):377-391. References Prehistoric metatherians Cretaceous mammals of North America Fossils of the United States Fossil taxa described in 2001 Prehistoric mammal genera {{cretaceous-mammal-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Marsupialia
Marsupials are any members of the mammalian infraclass Marsupialia. All extant marsupials are endemic to Australasia, Wallacea and the Americas. A distinctive characteristic common to most of these species is that the young are carried in a pouch. Marsupials include opossums, Tasmanian devils, kangaroos, koalas, wombats, wallabies, bandicoots, and the extinct thylacine. Marsupials represent the clade originating from the last common ancestor of extant metatherians, the group containing all mammals more closely related to marsupials than to placentals. They give birth to relatively undeveloped young that often reside in a pouch located on their mothers' abdomen for a certain amount of time. Close to 70% of the 334 extant species occur on the Australian continent (the mainland, Tasmania, New Guinea and nearby islands). The remaining 30% are found in the Americas—primarily in South America, thirteen in Central America, and one species, the Virginia opossum, in North Am ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Molar (tooth)
The molars or molar teeth are large, flat teeth A tooth ( : teeth) is a hard, calcified structure found in the jaws (or mouths) of many vertebrates and used to break down food. Some animals, particularly carnivores and omnivores, also use teeth to help with capturing or wounding prey, te ... at the back of the mouth. They are more developed in mammal, mammals. They are used primarily to comminution, grind food during mastication, 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 sometimes vestigial. Human anatomy In humans, the molar teeth have either four or five cusp (dentistry), 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 Third molar, wisdom tooth. It is the last tooth to appear, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Early Cretaceous
The Early Cretaceous (geochronological name) or the Lower Cretaceous ( chronostratigraphic name), is the earlier or lower of the two major divisions of the Cretaceous. It is usually considered to stretch from 145 Ma to 100.5 Ma. Geology Proposals for the exact age of the Barremian-Aptian boundary ranged from 126 to 117 Ma until recently (as of 2019), but based on drillholes in Svalbard the defining early Aptian Oceanic Anoxic Event 1a (OAE1a) was carbon isotope dated to 123.1±0.3 Ma, limiting the possible range for the boundary to c. 122–121 Ma. There is a possible link between this anoxic event and a series of Early Cretaceous large igneous provinces (LIP). The Ontong Java- Manihiki- Hikurangi large igneous province, emplaced in the South Pacific at c. 120 Ma, is by far the largest LIP in Earth's history. The Ontong Java Plateau today covers an area of 1,860,000 km2. In the Indian Ocean another LIP began to form at c. 120 Ma, the Kergue ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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