|
Trechnotheria
Trechnotheria is a group of mammals that includes the therians and some fossil mammals from the Mesozoic Era. In the Jurassic through Cretaceous periods, the group was endemic to what would be Asia and Africa. Trechnotheria has been assigned various ranks, but was originally described as a "superlegion" by the naming authority. A later node-based definition for Trechnotheria was the clade comprising the last common ancestor of ''Zhangheotherium'' and living therian mammals, and all its descendants. Characteristics Like most Mesozoic mammal groups, early trechnotherians are known mainly from their teeth. Hence, one of the most prominent features of this group is the "hypertrophied postvallum/prevallid shearing mechanism", along with other dental characters. Features of the shoulder blade, tibia, humerus, and ankle joint also diagnose this clade. Phylogeny A cladogram based on Luo, Cifelli & Kielan-Jaworowska, 2001, Luo, Kielan-Jaworowska & Cifelli, 2002 and, Kielan-Jaworo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gobiconodonta
Gobiconodonta is an order (biology), order of extinct mammals known from the Early Jurassic (such as ''Huasteconodon'') to early Late Cretaceous. They are generally held to be part of Eutriconodonta. Biology Like many other non-therian mammals, gobiconodonts retained classical mammalian synapomorphies like epipubic bones (and likely the associated reproductive constrictions), Venomous mammal, venomous spurs and sprawling limbs. However, the forelimb and shoulder anatomy of at least some species like ''Jeholodens'' are similar to those of therian mammals, though the hindlimbs remain more conservative. Gobiconodonts had Evolution of mammalian auditory ossicles, a modern ear anatomy, the main difference from therians being that the ear ossicles were still somewhat connected to the jaw via the Meckel's cartilage. Some information on gobiconodont soft-tissues can be seen in ''Spinolestes'', which was very well preserved, showing evidence of fur and internal organs. ''Spinolestes'' sh ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Zhangheotheriidae
Zhangheotheriidae is a possibly paraphyletic family of " symmetrodont" mammals that is currently known from Early Cretaceous deposits in China and Russia. Five genera are currently recognized, '' Anebodon'', '' Kiyatherium'', '' Maotherium'', '' Origolestes'', and ''Zhangheotherium ''Zhangheotherium'' is a genus of symmetrodont, an extinct order of mammals. Previously known from only the tall pointed crowned teeth, ''Zhangheotherium'', described from Liaoning Province, China, fossils in 1997, is the first symmetrodont known ...''. References Symmetrodonta Prehistoric mammal families Early Cretaceous mammals of Asia {{cretaceous-mammal-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Amphitheriida
Amphitheriidae is a family of Mesozoic mammals restricted to the Middle Jurassic of Britain, with indeterminate members also possibly known from the equivalently aged Itat Formation in Siberia and the Anoual Formation of Morocco. They were members of Cladotheria, more derived than members of Dryolestida, and forming a close relationship with Peramuridae.Panciroli E; Roger B.J. Benson; Richard J. Butler (2018).New partial dentaries of amphitheriid mammalian Palaeoxonodon ooliticus from Scotland, and posterior dentary morphology in early cladotherians. Acta Palaeontologica Polonica. in press. doi:10.4202/app.00434.2017. Amphitheriidae is the only family of the order Amphitheriida. Classification * Mammalia ** Yinotheria ( monotremes and relatives) ** Theriimorpha ***†Eutriconodonta ***Theriiformes ****†Allotheria *****†Gondwanatheria *****†Multituberculata **** Trechnotheria ***** † Spalacotheriidae ***** † Zhangheotheriidae ***** Cladotheria ****** † Meridiole ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Zatheria
Cladotheria is a clade (sometimes ranked as a legion) of mammals. It contains modern therian mammals (marsupials and placentals) and several extinct groups, such as the dryolestoids, amphitheriids and peramurids. The clade was named in 1975 by Malcolm McKenna. In 2002, it was defined as a node-based taxon containing "the common ancestor of dryolestids and living therians, plus all its descendants". A different, stem-based definition was given in 2013, in which Cladotheria contains all taxa that are closer to ''Mus musculus'' (the house mouse) than to the "symmetrodont" '' Spalacotherium tricuspidens''. Description Early cladotherians can be distinguished from other mammals by a number of derived traits (apomorphies). Their teeth differed from those of the "symmetrodonts" by the evolution of a talonid shelf ( hypoflexid) on the lower molars, which occluded with the paracone of the corresponding upper molars. A true talonid basin, allowing for the crushing and grinding of f ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dryolestida
Dryolestida is an extinct order of mammals, primarily and possibly exclusively known from the Jurassic and Cretaceous. They are considered members of the clade Cladotheria, close to the ancestry of therian mammals. It is also believed that they developed a fully mammalian jaw and also had the three middle ear bones. Most members of the group, as with most Mesozoic mammals, are only known from fragmentary tooth and jaw remains. The taxonomic composition of the group is contested. Aside from the uncontroversial Dryolestidae and the possibly paraphyletic Paurodontidae, which were small insectivores, known from the Middle Jurassic to Early Cretaceous of Laurasia, the Meridiolestida, a diverse group of mammals including both small insectivores and mid-large sized herbivores known from the Late Cretaceous to Miocene of South America and possibly Antarctica, are also often included. However, in many phylogenetic analyses, Meridiolestida are recovered as an unrelated group of cladothe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cladotheria
Cladotheria is a clade (sometimes ranked as a legion) of mammals. It contains modern therian mammals (marsupials and placentals) and several extinct groups, such as the dryolestoids, amphitheriids and peramurids. The clade was named in 1975 by Malcolm McKenna. In 2002, it was defined as a node-based taxon containing "the common ancestor of dryolestids and living therians, plus all its descendants". A different, stem-based definition was given in 2013, in which Cladotheria contains all taxa that are closer to ''Mus musculus'' (the house mouse) than to the "symmetrodont" '' Spalacotherium tricuspidens''. Description Early cladotherians can be distinguished from other mammals by a number of derived traits (apomorphies). Their teeth differed from those of the "symmetrodonts" by the evolution of a talonid shelf ( hypoflexid) on the lower molars, which occluded with the paracone of the corresponding upper molars. A true talonid basin, allowing for the crushing and grinding of f ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Spalacotheriida
Symmetrodonta is a group of Mesozoic mammals and mammal-like synapsids characterized by the triangular aspect of the Molar (tooth), molars when viewed from above, and the absence of a well-developed talonid. The traditional group of 'symmetrodonts' ranges in age from the latest Triassic to the Late Cretaceous, but most research in the last 20-30 years has concluded that they are not a true taxonomic group, but include several unrelated branches of the mammal tree. Despite this, the name is still used informally by some researchers for convenience, usually restricted to the spalacotheriids and zhangheotheriids Martin, T., 2018. 6. Mesozoic mammals—early mammalian diversity and ecomorphological adaptations. In Mammalian evolution, diversity and systematics (pp. 199-300). De Gruyter.. There are some symmetrodonts with acutely-triangulated molar cusps (“acute-angled symmetrodonts”) that seem to form a true monophyletic group, and lasted from the Early Cretaceous to the Campanian ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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 (Molar (tooth)#Tribosphenic, 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 t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Peramuridae
The family Peramuridae is a family of mammals that lived in the Late Jurassic and Early Cretaceous The Early Cretaceous (geochronology, geochronological name) or the Lower Cretaceous (chronostratigraphy, chronostratigraphic name), is the earlier or lower of the two major divisions of the Cretaceous. It is usually considered to stretch from 145& .... They are considered to be advanced cladotherians closely related to therian mammals as part of Zatheria. References * Cladotheria Jurassic mammals Prehistoric mammal families Tithonian first appearances Berriasian extinctions {{cretaceous-mammal-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cladogram
A cladogram (from Greek ''clados'' "branch" and ''gramma'' "character") is a diagram used in cladistics to show relations among organisms. A cladogram is not, however, an evolutionary tree because it does not show how ancestors are related to descendants, nor does it show how much they have changed, so many differing evolutionary trees can be consistent with the same cladogram. A cladogram uses lines that branch off in different directions ending at a clade, a group of organisms with a last common ancestor. There are many shapes of cladograms but they all have lines that branch off from other lines. The lines can be traced back to where they branch off. These branching off points represent a hypothetical ancestor (not an actual entity) which can be inferred to exhibit the traits shared among the terminal taxa above it. This hypothetical ancestor might then provide clues about the order of evolution of various features, adaptation, and other evolutionary narratives about an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aegialodontia
Aegialodontia is a clade of extinct early mammals, close to the origin of Boreosphenida. The clade includes some of the oldest known tribosphenic taxa, until the discovery of ''Tribactonodon'' from the Berriasian Durlston Formation in 2001 in paleontology, 2001, ''Aegialodon'' from the Valanginian Wadhurst Clay Formation was the oldest taxon with the tooth form. The Aptian to Albian taxon ''Kielantherium'' from Mongolia, formerly a synonym of ''Aegialodon'', is also within the group, sister to ''Aegialodon'' within Aegialodontidae. References Prehistoric mammals Tribosphenida {{Cretaceous-mammal-stub ... [...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 ancient ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
