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Triconodontidae
Triconodontidae is an extinct family of small, carnivorous mammals belonging to the order Eutriconodonta, endemic to what would become Asia, Europe, North America and probably also Africa and South America during the Jurassic through Cretaceous periods at least from 190–70.6 mya. Triconodontids can be distinguished from other eutriconodonts by the shape of their molars, which bore three main cusps of roughly equal size. During occlusion, the upper and lower molars interlocked tightly, producing a self-sharpening cutting edge. Historically, the triconodontids were thought to have a different occlusion pattern than other eutriconodonts, with the middle cusp of the lower molar (cusp a) fitting between the middle cusp (cusp A) and the front cusp (cusp B) of the upper molar, as in the basal mammaliaform ''Morganucodon''. However, a 2020 study on ''Priacodon'' suggests that triconodontids occluded their molars in the same manner as other eutriconodonts (so-called "embrasure occlusio ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Eutriconodonta
Eutriconodonta is an order of early mammals. Eutriconodonts existed in Asia, Africa, Europe, North and South America during the Jurassic and the Cretaceous periods. The order was named by Kermack ''et al.'' in 1973 as a replacement name for the paraphyletic Triconodonta. Traditionally seen as the classical Mesozoic small mammalian insectivores, discoveries over the years have shown them to be among the best examples of the diversity of mammals in this time period, including a vast variety of bodyplans, ecological niches and locomotion methods. Classification "Triconodonta" had long been used as the name for an order of early mammals which were close relatives of the ancestors of all present-day mammals, characterized by molar teeth with three main cusps on a crown that were arranged in a row. The group originally included only the family Triconodontidae and taxa that were later assigned to the separate family Amphilestidae, but was later expanded to include other taxa such ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Volaticotherini
Volaticotherini is a clade of eutriconodont mammals from the Mesozoic. In addition to the type genus ''Volaticotherium'', it includes the genera ''Argentoconodon'', ''Ichthyoconodon'', and potentially ''Triconolestes''. Since most remains are primarily teeth, they are foremostly diagnosticated by their highly distinctive molar (tooth), molars. However, the remains of one species, ''Volaticotherium antiquum'', show that at least some members of this clade were capable of Gliding flight, gliding. and ''Argentoconodon'' shares similar post-cranial features that also indicate aerial locomotion. As such, this clade contains some of the oldest known aerial mammals, alongside the various gliding haramiyidans. Definition Volaticotherini is phylogenetically defined as the clade derived from the most recent common ancestor of ''Argentoconodon'', ''Ichthyoconodon,'' and ''Volaticotherium''. History ''Ichthyoconodon'' was the first described member of this group, back in 1995, previously ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Jugulator Amplissimus
''Jugulator'' is an extinct genus of mammals from the Cretaceous of North America. It contains one species, ''Jugulator amplissimus''. A eutriconodont, it is known from the Cedar Mountain Formation, and is both a large sized and possibly ecologically specialised taxon, showcasing the diversity of mammals in the Mesozoic. Description ''Jugulator'' is known primarily from isolated teeth and dentaries. The species is most distinctive in regards to its large size, being among the largest mammals in the region, some lower molars exceeding 5 mm in length and with an estimated body weight of about 750 g. The medial lower incisor is greatly enlarged, with a mitten-shaped crown that bears sharp cutting surfaces. Phylogeny Always recognised as a triconodontid eutriconodont, the most recent phylogenetic studies recover ''Jugulator'' as the sister taxon of a clade comprising ''Volaticotherium'', '' Ichthyoconodon'', '' Triconolestes'', and '' Argentoconodon'', known as Volaticotherini ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Alticonodon
''Alticonodon'' is a genus of extinct mammal from the Late Cretaceous of North America. It is the geologically youngest known eutriconodont, and is a fairly more specialised animal than earlier representatives of this clade. Description ''Alticonodon'' is currently a monotypic genus, represented exclusively by ''A. lindoei''. It is known from the Milk River Formation deposits of the early Campanian of Alberta, Canada. It is known from two specimens: a dentary fragment bearing two molars, and an isolated lower last molar. Classification ''Alticonodon'' has been consistently recovered as a triconodontid, and more specifically as an alticonodontine, though the latter term may be redundant in relation to the rest of Triconodontidae. Biology Compared to earlier eutriconodonts, ''Alticonodon'' has molars better specialised for shearing. As eutriconodonts as a group had shearing molars due to their carnivorous habits, it can be inferred that ''Alticonodon'' was hypercarnivorous. This ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Triconodon
''Triconodon'' ("three coned tooth") is a genus of extinct mammal from the Early Cretaceous of England and France with two known species: ''T. mordax'' and ''T. averianovi''. First described in 1859 by Richard Owen,R. Owen. 1859. Palaeontology. '' Encyclopedia Britannica, 8th ed.'' 17:91-176 . Wagner/P. Wagner it is the type genus for the order Triconodonta, a group of mammals characterised by their three-cusped (triconodont) molar teeth. Since then, this "simplistic" type of dentition has been understood to be either ancestral for mammals or else to have evolved multiple times, rendering "triconodonts" a paraphyletic or polyphyletic assemblage respectively, but several lineages of "triconodont" mammals do form a natural, monophyletic group, known as Eutriconodonta, of which ''Triconodon'' is indeed part of. ''Triconodon'', therefore, is significant in the understanding of the evolution of mammals by originating the understanding of the "triconodont" grade and eutriconodont ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Priacodon
''Priacodon'' is an extinct genus of Late Jurassic eutriconodont mammal from the Alcobaça Formation of Portugal and the Morrison Formation of the midwestern United States. It is present in stratigraphic zones 4–6 of the latter.Foster, J. (2007). "Appendix." ''Jurassic West: The Dinosaurs of the Morrison Formation and Their World''. Indiana University Press. pp. 327–329. The genus contains four known species: ''Priacodon ferox'', ''Priacodon fruitaensis'', ''Priacodon lulli'' and ''Priacodon robustus''. Jaw and teeth A study on the jaw and teeth of ''Priacodon'' suggests that eutriconodonts, while specialised towards carnivory, had a more passive jaw roll than modern therian carnivores. It also demonstrates that embrasure occlusion was present in all eutriconodonts, as opposed to one-to-one patterns as previously assumed for the family Triconodontidae. See also * Paleobiota of the Morrison Formation The Morrison Formation is a distinctive sequence of Late Jurassic sedime ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Carnivorous
A carnivore , or meat-eater (Latin, ''caro'', genitive ''carnis'', meaning meat or "flesh" and ''vorare'' meaning "to devour"), is an animal or plant whose food and energy requirements derive from animal tissues (mainly muscle, fat and other soft tissues) whether through hunting or scavenging. Nomenclature Mammal order The technical term for mammals in the order Carnivora is ''carnivoran'', and they are so-named because most member species in the group have a carnivorous diet, but the similarity of the name of the order and the name of the diet causes confusion. Many but not all carnivorans are meat eaters; a few, such as the large and small cats (felidae) are ''obligate'' carnivores (see below). Other classes of carnivore are highly variable. The Ursids, for example: While the Arctic polar bear eats meat almost exclusively (more than 90% of its diet is meat), almost all other bear species are omnivorous, and one species, the giant panda, is nearly exclusively herbivorous. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Meiconodon
''Meiconodon'' is an extinct genus of alticonodontine triconodontid which existed in China during the early Cretaceous period ( Aptian/Albian age). It was described by Nao Kusuhashi, Yaoming Hu, Yuanqing Wang, Satoshi Hirasawa and Hiroshige Matsuoka in 2009 and the type species In zoological nomenclature, a type species (''species typica'') is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the species that contains the biological type specime ... is ''Meiconodon lii''. References Cretaceous mammals Eutriconodonts Fossil taxa described in 2009 Extinct mammals of Asia Taxa named by Nao Kusuhashi Taxa named by Yaoming Hu Taxa named by Yuanqing Wang Taxa named by Satoshi Hirasawa Taxa named by Hiroshige Matsuoka Prehistoric mammal genera {{cretaceous-mammal-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cusp (anatomy)
A cusp is a pointed, projecting, or elevated feature. In animals, it is usually used to refer to raised points on the crowns of teeth. The concept is also used with regard to the leaflets of the four heart valves. The mitral valve, which has two cusps, is also known as the bicuspid valve, and the tricuspid valve has three cusps. In humans A cusp is an occlusal or incisal eminence on a tooth. Canine teeth, otherwise known as cuspids, each possess a single cusp, while premolars, otherwise known as bicuspids, possess two each. Molars normally possess either four or five cusps. In certain populations the maxillary molars, especially first molars, will possess a fifth cusp situated on the mesiolingual cusp known as the Cusp of Carabelli. Buccal Cusp- One other variation of the upper first premolar is the 'Uto-Aztecan' upper premolar. It is a bulge on the buccal cusp that is only found in Native American Indians, with highest frequencies of occurrence in Arizona. The name is no ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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 sometimes vestigial. 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 (maxillary) and lower (mandib ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Annum
A year or annus is the orbital period of a planetary body, for example, the Earth, moving in its orbit around the Sun. Due to the Earth's axial tilt, the course of a year sees the passing of the seasons, marked by change in weather, the hours of daylight, and, consequently, vegetation and soil fertility. In temperate and subpolar regions around the planet, four seasons are generally recognized: spring, summer, autumn and winter. In tropical and subtropical regions, several geographical sectors do not present defined seasons; but in the seasonal tropics, the annual wet and dry seasons are recognized and tracked. A calendar year is an approximation of the number of days of the Earth's orbital period, as counted in a given calendar. The Gregorian calendar, or modern calendar, presents its calendar year to be either a common year of 365 days or a leap year of 366 days, as do the Julian calendars. For the Gregorian calendar, the average length of the calendar year (the mea ... [...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 Earth b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
