|
Eutriconodonts
Eutriconodonta is an order of early mammals. Eutriconodonts existed in Asia (including pre-contact India), 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 expande ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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 190–66 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] |
Triconodon Owen
''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 cla ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gobiconodontidae
Gobiconodontidae is a family of extinct mammals that ranged from the mid-Jurassic to the early Late Cretaceous, though most common during the Early Cretaceous. The Gobiconodontids form a diverse lineage of carnivorous non-therian mammals, and include some of the best preserved Mesozoic mammal specimens. Biology Like many other non-therian mammals, gobiocontids retained classical mammalian synapomorphies like epipubic bones (and likely the associated reproductive constrictions), venomous spurs and sprawling limbs. Through ''Spinolestes'' we also know that they had fur similar to that of modern mammals, with compound hair follicles with primary and secondary hairs. ''Spinolestes'' also possesses a clear diaphragm like modern mammals, as well as spines, dermal scutes and an ossified Meckel's cartilage. Furthermore, it may also display signs of dermatophytosis, suggesting that gobiconodontids, like modern mammals, were vulnerable to this type of fungal infection. Gobiconodontid de ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mammal
A mammal () is a vertebrate animal of the Class (biology), class Mammalia (). Mammals are characterised by the presence of milk-producing mammary glands for feeding their young, a broad neocortex region of the brain, fur or hair, and three Evolution of mammalian auditory ossicles, middle ear bones. These characteristics distinguish them from reptiles and birds, from which their ancestors Genetic divergence, diverged in the Carboniferous Period over 300 million years ago. Around 6,640 Neontology#Extant taxon, extant species of mammals have been described and divided into 27 Order (biology), orders. The study of mammals is called mammalogy. The largest orders of mammals, by number of species, are the rodents, bats, and eulipotyphlans (including hedgehogs, Mole (animal), moles and shrews). The next three are the primates (including humans, monkeys and lemurs), the Artiodactyl, even-toed ungulates (including pigs, camels, and whales), and the Carnivora (including Felidae, ... [...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 molars. However, the remains of one species, '' Volaticotherium antiquum'', show that at least some members of this clade were capable of 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 usually ranked among eut ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sangarotherium
''Sangarotherium'' is an extinct genus of eutriconodont mammal from the Early Cretaceous of Russia. It contains a single species, ''Sangarotherium aquilonium'', known from a lower jaw fragment with one fully erupted tooth and fragments of two other teeth. This fossil was discovered at Teete, a microvertebrate site from the Batylykh Formation of the Sangar Series, in the Siberian Republic of Yakutia. Like most other eutriconodonts, the complete molariform tooth has five pointed cusps aligned in a straight line (from front to back, cusps e, b, a, c, and d). The largest cusps (in order) are a, b, and c, while cusps e and d are very small. These cusp proportions differ from known eutriconodont families, so ''Sangarotherium'' is classified as Eutriconodonta incertae sedis. ''Sangarotherium'' also bears an extensive Meckel's groove, and it is the only eutriconodont with a prominent rugose coronoid facet. Bajpai et al 2024 recovers it as closely related to Volaticotherini.Bajpai, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dyskritodon
''Dyskritodon'' ("tooth of unknown origin", from Greek language, Greek δυσκρίτος, "''dyskritos''"Sigogneau-Russell, D. (1995) Two possibly aquatic triconodont mammals from the Early Cretaceous of Morocco. Acta Palaeontologica Polonica. 40(2), p.149-162.) is a genus of extinct mammal from the Early Cretaceous of Morocco, and possibly the Early Jurassic of India. Of uncertain affinities, it is tentatively described as a eutriconodont. Description The type species, ''D. amazighi'', is known from the Ksar Metlili Formation in the Atlas Mountains, dating to the Berriasian. It is known from several Molar (tooth), molars, about 1.85 mm long. These teeth are noted for being rather high and narrow crowned, bearing three main cusps that decrease in height posteriorly, as well as two minuscule mesial cusps. ''D. indicus'' is known from a single lower molar tooth from the Kota Formation, dating to the Hettangian-Pliensbachian. It is very similar to ''D. amazighi'', differing in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Amphidontidae
The Amphidontidae are a family of extinct mammals from the Early Jurassic to the Early Cretaceous, belonging to the eutriconodonts. It contains most of the species previously belonged to Amphilestidae. Phylogeny Cladogram A cladogram (from Greek language, Greek ''clados'' "branch" and ''gramma'' "character") is a diagram used in cladistics to show relations among organisms. A cladogram is not, however, an Phylogenetic tree, evolutionary tree because it does not s ... after Marisol Montellano, James A. Hopson, James M. Clark (2008) and Gao ''et al.'' (2010). Taxonomy Based on the works by Mikko HaaramoMikko's Phylogeny Archiv and the Palaeofile website.Paleofile.com (net, info) . *Family †Amphidontidae Simpson 1925 **Genus †'' Acinacodus'' Lopatin, Maschenko & Averianov 2010 ***Species †'' Acinacodus tagaricus'' Lopatin, Maschenko & Averianov 2010 **Genus †'' Aploconodon'' Simpson 1925 ***Species †'' Aploconodon comoensis'' Simpson 1925 **Genus †'' Comodon'' K ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Volaticotherium
''Volaticotherium antiquum'' (meaning "ancient gliding beast") is an extinct, gliding, insectivorous mammal that lived in Asia during the Jurassic period, around 164 mya. It is the only member of the genus ''Volaticotherium''. The discovery of ''Volaticotherium'' provided the earliest-known record of a gliding mammal (70 million years older than the next oldest example), until the discovery of the contemporary haramiyidans ''Maiopatagium'', ''Vilevolodon'' and '' Xianshou'', and provided further evidence of mammalian diversity during the Mesozoic Era. The closely related and significantly older '' Argentoconodon'' shows similar post-cranial adaptations for aerial locomotion also seen in ''Volaticotherium''. Discovery The only known fossil of ''Volaticotherium'' was recovered from the Daohugou Beds of Ningcheng County, Inner Mongolia, China. The age of the Daohugou Beds is currently uncertain and the subject of debate, but most studies suggest an age of around 164 plus or min ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Repenomamus
''Repenomamus'' (Latin: "reptile" (reptilis), "mammal" (mammalis)) is a genus of opossum- to badger-sized Gobiconodontidae, gobiconodontid mammal containing two species, ''Repenomamus robustus'' and ''Repenomamus giganticus''. Both species are known from fossils found in China that date to the early Cretaceous period, about 125-123.2 million years ago. ''R. robustus'' is one of several Mesozoic mammals for which there is good evidence that it fed on vertebrates, including dinosaurs. Though it is not entirely clear whether these animals primarily hunted live dinosaurs or scavenged dead ones, evidence for the former is present in fossilized remains showcasing the results of what was most likely a predation attempt by ''R. robustus'' directed at a specimen of the dinosaur ''Psittacosaurus, Psittacosaurus lujiatunensis''. ''R. giganticus'' is among the largest mammals known from the Mesozoic era, only surpassed by ''Patagomaia''. Classification and discovery The fossils were rec ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Paraphyletic
Paraphyly is a taxonomic term describing a grouping that consists of the grouping's last common ancestor and some but not all of its descendant lineages. The grouping is said to be paraphyletic ''with respect to'' the excluded subgroups. In contrast, a monophyletic grouping (a clade) includes a common ancestor and ''all'' of its descendants. The terms are commonly used in phylogenetics (a subfield of biology) and in the tree model of historical linguistics. Paraphyletic groups are identified by a combination of synapomorphies and symplesiomorphies. If many subgroups are missing from the named group, it is said to be polyparaphyletic. The term received currency during the debates of the 1960s and 1970s accompanying the rise of cladistics, having been coined by zoologist Willi Hennig to apply to well-known taxa like Reptilia (reptiles), which is paraphyletic with respect to birds. Reptilia contains the last common ancestor of reptiles and all descendants of that ancestor exc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cretaceous
The Cretaceous ( ) is a geological period that lasted from about 143.1 to 66 mya (unit), million years ago (Mya). It is the third and final period of the Mesozoic Era (geology), Era, as well as the longest. At around 77.1 million years, it is the ninth and longest geological period of the entire Phanerozoic. The name is derived from the Latin , 'chalk', which is abundant in the latter half of the period. It is usually abbreviated K, for its German translation . The Cretaceous was a period with a relatively warm climate, resulting in high Sea level#Local and eustatic, eustatic sea levels that created numerous shallow Inland sea (geology), 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 largely ice-free, although there is some evidence of brief periods of glaciation during the cooler first half, and forests extended to the poles. Many of the dominant taxonomic gr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
