|
Vincelestidae
''Vincelestes'' ("Vince's thief") is an extinct genus of actively mobile mammal, that lived in what would be South America during the Early Cretaceous from 130 to 112 Annum, mya, existing for approximately . Description ''Vincelestes neuquenianus'' is the only species known to date. Specimens were found in La Amarga Formation of southern Neuquén Province, Argentina. The remains of only nine individuals were recovered from this site. The back teeth of ''Vincelestes'' were similar to those of therians in that they were capable of cutting and grinding. This enabled them to process food more efficiently. Diet In one study on Mesozoic mammal mandibles, ''Vincelestes'' plots with herbivorous and omnivorous taxa. Phylogeny Although not the direct ancestor of therians, ''Vincelestes'' is important because it gives an idea of what the ancestor of both placental and marsupial mammals might have looked like, and also gives an indication of when these mammals may have originated. Some ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Barremian
The Barremian is an age in the geologic timescale (or a chronostratigraphic stage) between 129.4 ± 1.5 Ma (million years ago) and 121.4 ± 1.0 Ma). It is a subdivision of the Early Cretaceous Epoch (or Lower Cretaceous Series). It is preceded by the Hauterivian and followed by the Aptian Stage.See Gradstein ''et al.'' (2004) or the online geowhen database (link below) Stratigraphic definitions The original type locality for the Barremian Stage is in the vicinity of the village of Barrême, Alpes-de-Haute-Provence, France. Henri Coquand defined the stage and named it in 1873. The base of the Barremian is determined by the first appearance of the ammonites ''Spitidiscus hugii'' and ''Spitidiscus vandeckii''. The end of the Barremian is determined by the geomagnetic reversal at the start of the M0r chronozone, which is biologically near the first appearance of the ammonite '' Paradeshayesites oglanlensis''. Regional equivalents The Barremian falls in the Gallic epoch, a su ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Marsupial
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 America, n ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fossil Taxa Described In 1986
A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, Seashell, shells, exoskeletons, stone imprints of animals or microbes, objects preserved in #Resin, amber, hair, petrified wood and DNA remnants. The totality of fossils is known as the ''fossil record''. Paleontology is the study of fossils: their age, method of formation, and evolutionary significance. Specimens are usually considered to be fossils if they are over 10,000 years old. The oldest fossils are around 3.48 billion years old to 4.1 billion years old. Early edition, published online before print. The observation in the 19th century that certain fossils were associated with certain rock stratum, strata led to the recognition of a geological timescale and the relative ages of different fossils. The development of radiometric dating techniques in the early 20th century allowed scientists to quantitativ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fossils Of Argentina
A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserved in amber, hair, petrified wood and DNA remnants. The totality of fossils is known as the ''fossil record''. Paleontology is the study of fossils: their age, method of formation, and evolutionary significance. Specimens are usually considered to be fossils if they are over 10,000 years old. The oldest fossils are around 3.48 billion years old to 4.1 billion years old. Early edition, published online before print. The observation in the 19th century that certain fossils were associated with certain rock strata led to the recognition of a geological timescale and the relative ages of different fossils. The development of radiometric dating techniques in the early 20th century allowed scientists to quantitatively measure the absolute ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cretaceous Argentina
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] |
Early Cretaceous Mammals Of South America
{{disambiguation, geo ...
Early may refer to: History * The beginning or oldest part of a defined historical period, as opposed to middle or late periods, e.g.: ** Early Christianity ** Early modern Europe Places in the United States * Early, Iowa * Early, Texas * Early Branch, a stream in Missouri * Early County, Georgia Other uses * ''Early'' (Scritti Politti album), 2005 * ''Early'' (A Certain Ratio album), 2002 * Early (name) * Early effect, an effect in transistor physics * Early Records, a record label * the early part of the morning See also * Earley (other) Earley is a town in England. Earley may also refer to: * Earley (surname), a list of people with the surname Earley * Earley (given name), a variant of the given name Earlene * Earley Lake, a lake in Minnesota *Earley parser, an algorithm *Earley ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aptian Genus Extinctions
The Aptian is an age in the geologic timescale or a stage in the stratigraphic column. It is a subdivision of the Early or Lower Cretaceous Epoch or Series and encompasses the time from 121.4 ± 1.0 Ma to 113.0 ± 1.0 Ma (million years ago), approximately. The Aptian succeeds the Barremian and precedes the Albian, all part of the Lower/Early Cretaceous. The Aptian partly overlaps the upper part of the Western European Urgonian Stage. The Selli Event, also known as OAE1a, was one of two oceanic anoxic events in the Cretaceous Period, which occurred around 120 Ma and lasted approximately 1 to 1.3 million years. The Aptian extinction was a minor extinction event hypothesized to have occurred around 116 to 117 Ma.Archangelsky, Sergio.The Ticó Flora (Patagonia) and the Aptian Extinction Event" ''Acta Paleobotanica'' 41(2), 2001, pp. 115-22. Stratigraphic definitions The Aptian was named after the small city of Apt in the Provence region of France, which is also known for its cry ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Barremian Genus First Appearances
The Barremian is an age in the geologic timescale (or a chronostratigraphic stage) between 129.4 ± 1.5 Ma (million years ago) and 121.4 ± 1.0 Ma). It is a subdivision of the Early Cretaceous Epoch (or Lower Cretaceous Series). It is preceded by the Hauterivian and followed by the Aptian Stage.See Gradstein ''et al.'' (2004) or the online geowhen database (link below) Stratigraphic definitions The original type locality for the Barremian Stage is in the vicinity of the village of Barrême, Alpes-de-Haute-Provence, France. Henri Coquand defined the stage and named it in 1873. The base of the Barremian is determined by the first appearance of the ammonites ''Spitidiscus hugii'' and ''Spitidiscus vandeckii''. The end of the Barremian is determined by the geomagnetic reversal at the start of the M0r chronozone, which is biologically near the first appearance of the ammonite '' Paradeshayesites oglanlensis''. Regional equivalents The Barremian falls in the Gallic epoch, a subdiv ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Australosphenida
The Australosphenida are a clade of mammals, containing mammals with tribosphenic molars, known from the Jurassic to Mid-Cretaceous of Gondwana. They are thought to have acquired their tribosphenic molars independently from those of Tribosphenida. Fossils of australosphenidans have been found from the Jurassic of Madagascar and Argentina, and Cretaceous of Australia and Argentina. Monotremes have also been considered a part of this group in some studies, but this is disputed. Taxonomy This grouping includes the following taxa: *†Henosferidae, including the genera '' Ambondro'', ''Asfaltomylos'', and ''Henosferus'' from the Jurassic of Argentina and Madagascar. *†Ausktribosphenidae, including the genera ''Ausktribosphenos'', '' Bishops'' from the Lower Cretaceous of Australia and Mid-Cretaceous of Argentina *†''Vincelestes'', sometimes recovered as an australosphenidan (when not inversely considered a cladotherian).Nicholas Chimento, Frederico Agnolin, Agustin Martinelli, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Placental
Placental mammals (infraclass Placentalia ) are one of the three extant subdivisions of the class Mammalia, the other two being Monotremata and Marsupial 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 po ...ia. Placentalia contains the vast majority of extant mammals, which are partly distinguished from monotremes and marsupials in that the fetus (biology), fetus is carried in the uterus of its mother to a relatively late stage of development. The name is something of a misnomer considering that marsupials also nourish their fetuses via a placenta, though for a relatively briefer period, giving birth to less developed young which are then nurtured for a period inside the mother's pouch (marsupial), pouch. Anatomical features Placental mammals are anatomically distinguished from othe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aptian
The Aptian is an age in the geologic timescale or a stage in the stratigraphic column. It is a subdivision of the Early or Lower Cretaceous Epoch or Series and encompasses the time from 121.4 ± 1.0 Ma to 113.0 ± 1.0 Ma (million years ago), approximately. The Aptian succeeds the Barremian and precedes the Albian, all part of the Lower/Early Cretaceous. The Aptian partly overlaps the upper part of the Western European Urgonian Stage. The Selli Event, also known as OAE1a, was one of two oceanic anoxic events in the Cretaceous Period, which occurred around 120 Ma and lasted approximately 1 to 1.3 million years. The Aptian extinction was a minor extinction event hypothesized to have occurred around 116 to 117 Ma.Archangelsky, Sergio.The Ticó Flora (Patagonia) and the Aptian Extinction Event" ''Acta Paleobotanica'' 41(2), 2001, pp. 115-22. Stratigraphic definitions The Aptian was named after the small city of Apt in the Provence region of France, which is also known for its cry ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Theria
Theria (; Greek: , wild beast) is a subclass of mammals amongst the Theriiformes. Theria includes the eutherians (including the placental mammals) and the metatherians (including the marsupials) but excludes the egg-laying monotremes. Characteristics Therian mammals give birth (''see viviparity'') to live young without a shelled egg. This is possible thanks to key proteins called syncytins which allow exchanges between the mother and its offspring through a placenta, even rudimental ones such as in marsupials. Genetic studies have suggested a viral origin of syncytins through the endogenization process. The marsupials and the placental mammals evolved from a common therian ancestor that gave live birth by suppressing the mother's immune system. While the marsupials continued to give birth to an underdeveloped fetus after a short pregnancy, the ancestors of placental mammals gradually evolved a prolonged pregnancy. Therian mammals no longer have the coracoid bone, con ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
_(white_background).jpg "Click for more on -> Marsupial")
