|
Mammaliaforms
Mammaliaformes ("mammalian forms") is a clade that contains the crown group mammals and their closest extinct relatives; the group radiated from earlier probainognathian cynodonts. It is defined as the clade originating from the most recent common ancestor of Morganucodonta and the crown group mammals; the latter is the clade originating with the most recent common ancestor of extant Monotremata, Marsupialia, and Placentalia. Besides Morganucodonta and the crown group mammals, Mammaliaformes includes Docodonta and ''Hadrocodium'' as well as the Triassic ''Tikitherium'', the earliest known member of the group. Mammaliaformes is a term of phylogenetic nomenclature. In contrast, the assignment of organisms to Mammalia has traditionally been founded on traits and, on this basis, Mammalia is slightly more inclusive than Mammaliaformes. In particular, trait-based taxonomy generally includes '' Adelobasileus'' and '' Sinoconodon'' in Mammalia, though they fall outside the Mammaliafor ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Docodonta
Docodonta is an order of extinct mammaliaforms that lived during the Mesozoic, from the Middle Jurassic to Early Cretaceous. They are distinguished from other early mammaliaforms by their relatively complex molar teeth, from which the order gets its name. Until recently, Docodonta were represented primarily by teeth and jaws found across former Laurasia, (modern-day North America, Europe, and Asia). However, recent discoveries in China include some exceptionally well preserved, almost complete body fossils. Description Skeletal traits Docodonts have a long and low mandible (lower jaw), formed primarily by the tooth-bearing dentary bone. The dentary connects to the cranium via a joint with the squamosal, a connection which is strengthened relative to earlier mammaliaforms. The other bones in the jaw, known as postdentary elements, are still connected to the dentary and lie within a groove (the postdentary trough) in the rear part of the dentary’s inner edge. Nevertheless, th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Castorocauda
''Castorocauda'' is an extinct, semi-aquatic, superficially otter-like genus of docodont mammaliaforms with one species, ''C. lutrasimilis''. It is part of the Yanliao Biota, found in the Daohugou Beds of Inner Mongolia, China dating to the Middle to Late Jurassic. It was part of an explosive Middle Jurassic radiation of Mammaliaformes moving into diverse habitats and niches. Its discovery in 2006, along with the discovery of other unusual mammaliaforms, disproves the previous hypothesis of Mammaliaformes remaining evolutionarily stagnant until the extinction of the non-avian dinosaurs. Weighing an estimated , ''Castorocauda'' is the largest known Jurassic mammaliaform. It is the earliest known mammaliaform with aquatic adaptations or a fur pelt. It was also adapted for digging, and its teeth are similar to those of seals and Eocene whales, collectively suggesting it behaved similarly to the modern-day platypus and river otters and ate primarily fish. It lived in a wet, sea ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Megazostrodon
''Megazostrodon'' is an extinct genus of basal mammaliaforms belonging to the order Morganucodonta. It is approximately 200 million years old.Fur and Fangs: Mammal Origins . Palaeobiology and Biodiversity Research Group, University of Bristol. Two species are known: ''M. rudnerae'' from the of and , and ''M. chenali'' from the |
Bocaconodon
''Bocaconodon'' (meaning "La Boca conical tooth") is an early mammaliaform genus that lived during the Pliensbachian (Early Jurassic) of Mexico. The type and only species, ''Bocaconodon tamaulipensis'' (referring to Tamaulipas, where the holotype was found), was named and described in 2008. It is known from a single specimen, a partial right dentary bone preserving two nearly complete molar teeth and the rear portion of a third molar. The specimen was found at the Huizachal Canyon locality, "a Pliensbachian floodplain siltstone in the La Boca Formation". Description The only known specimen of ''Bocaconodon'' (IGM 6617) is a partial right dentary bone, which preserves most of the last two molar teeth and the rear portion of a third molar. The preserved part of the dentary was quite thin from top to bottom, with the thinnest part being beneath the last molar. Behind the tooth row there was a facet that may have housed the coronoid bone. At the rear end of the dentary, there wa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gondtherium
''Gondtherium'' is a genus of extinct mammaliaform from the Kota Formation in India. It was considered a docodontan by those who described it, but it remains unclear if this is the case. ''Gondtherium'' was found in the Kota Formation, which is considered to be between Middle Jurassic and Early Cretaceous in age. Other Mesozoic mammaliaforms found there include members of Morganucodonta Morganucodonta ("Glamorgan teeth") is an extinct order of basal Mammaliaformes, a group including crown-group mammals (Mammalia) and their close relatives. Their remains have been found in Southern Africa, Western Europe, North America, India an ... and Amphilestidae. The authors who described ''Gondtherium'' - which is known from only a single worn and fragmentary molar tooth - considered it to be a docodontan based on the tooth cusps. However, this has been disputed by several subsequent researchers, and so the exact identity of ''Gondtherium'' remains unresolved.Kielan-Jaworowska Z, Cifel ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hadrocodium
''Hadrocodium wui'' is an extinct mammaliaform that lived during the Sinemurian stage of the Early Jurassic approximately in the Lufeng Formation of the Lufeng Basin in what is now the Yunnan province in south-western China (, paleocoordinates ). It is considered as the closest relative of the class Mammalia. The fossil of this mouse-like, paper-clip sized animal was discovered in 1985 but was then interpreted as a juvenile morganucodontid. ''Hadrocodium'' remained undescribed until 2001; since then its large brain and advanced ear structure have greatly influenced the interpretation of the earliest stages of mammalian evolution, as these mammalian characters could previously be traced only to some . ''Hadrocodium'' is known only from a skull long, and the body mass is estimated to have been , making it one of the smallest Mesozoic mammaliaforms (in contrast, the related ancestral mammal would have been bigger, about ). The name ''Hadrocodium'' alludes to its large cranial c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mammal
Mammals () are a group of vertebrate animals constituting the class (biology), class Mammalia (), characterized by the presence of mammary glands which in Female#Mammalian female, females produce milk for feeding (nursing) their young, a neocortex (a region of the brain), fur or hair, and three ossicles, middle ear bones. These characteristics distinguish them from reptiles (including birds) from which they Genetic divergence, diverged in the Carboniferous, over 300 million years ago. Around 6,400 extant taxon, extant species of mammals have been described divided into 29 Order (biology), orders. The largest Order (biology), orders, in terms of number of species, are the rodents, bats, and Eulipotyphla (hedgehogs, Mole (animal), moles, shrews, and others). The next three are the Primates (including humans, apes, monkeys, and others), the Artiodactyla (cetaceans and even-toed ungulates), and the Carnivora (cats, dogs, pinniped, seals, and others). In terms of cladistic ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kuehneotheriidae
Kuehneotheriidae is an extinct family of mammaliaforms traditionally placed within ' Symmetrodonta', though now generally considered more basal than true symmetrodonts. All members of Kuehneotheriidae which have been found so far are represented only by teeth, but these teeth have features which have led paleontologists to classify kuehneotheriids as very close relatives of the first true mammals. But fossil clades based solely on teeth often lead to difficulties ( Ausktribosphenidae being a good example), and it is not possible to draw significant conclusions about mammalian evolution The evolution of mammals has passed through many stages since the first appearance of their synapsid ancestors in the Pennsylvanian (geology), Pennsylvanian sub-period of the late Carboniferous period. By the mid-Triassic, there were many synaps ... from Kuehneotheriidae unless some more complete skeletons are found. See also * Evolution of mammals References Prehistoric mammaliaforms ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Morganucodonta
Morganucodonta (" Glamorgan teeth") is an extinct order of basal Mammaliaformes, a group including crown-group mammals (Mammalia) and their close relatives. Their remains have been found in Southern Africa, Western Europe, North America, India and China. The morganucodontans were probably insectivorous and nocturnal, though like eutriconodonts some species attained large sizes and were carnivorous. Nocturnality is believed to have evolved in the earliest mammals in the Triassic (called the nocturnal bottleneck) as a specialisation that allowed them to exploit a safer, night-time niche, while most larger predators were likely to have been active during the day (though some dinosaurs, for example, were nocturnal as well). Anatomy and biology Morganucodontans had a double jaw articulation made up of the dentary- squamosal joint as well as a quadrate-articular one. This implies that they also retained one of their postdentary bones: the articular. There is a trough at the b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Woutersia
''Woutersia'' was a Triassic genus of ' symmetrodont' and the only representative of the family Woutersiidae. It was originally classified as a kuehneotheriid, but it has been suggested that it may be related to Docodonta. Remains of ''W. mirabilis'' and ''W. butleri'' have been found in the Gres à Avicula contorta Formation at Saint-Nicolas-de-Port, France, while ''W. mirabilis'' has been found in Varangéville, France; remains have been dated to the Late Triassic The Late Triassic is the third and final epoch (geology), epoch of the Triassic geologic time scale, Period in the geologic time scale, spanning the time between annum, Ma and Ma (million years ago). It is preceded by the Middle Triassic Epoch ..., 205.6 to 201.6 Ma. References Prehistoric mammaliaforms Prehistoric cynodont genera Rhaetian life Late Triassic synapsids of Europe Triassic France Fossils of France Fossil taxa described in 1983 Taxa named by Denise Sigogneau‐Russell {{paleo-thera ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Haramiyida
Haramiyida ("thief" from Arabic الحرامية (al ḥarāmiyah), "thief, bandit") is a possibly polyphyletic order of mammaliaform cynodonts or mammals of controversial taxonomic affinites. Their teeth, which are by far the most common remains, resemble those of the multituberculates. However, based on '' Haramiyavia'', the jaw is less derived; and at the level of evolution of earlier basal mammals like ''Morganucodon'' and ''Kuehneotherium'', with a groove for ear ossicles on the dentary. If they are early multituberculates, they would be the longest lived mammalian clade of all time. However, a more recent study in November 2015 may dispute this and suggested the Haramiyida were not crown mammals, but were part of an earlier offshoot of mammaliaformes instead. It is also disputed whether the Late Triassic species are closely related to the Jurassic and Cretaceous members belonging to Euharamiyida/Eleutherodontida, as some phylogenetic studies recover the two groups as unrela ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tikitherium
''Tikitherium'' is an extinct genus of mammaliaforms from the Late Triassic. It is thought to be an insectivore and a close relative to Docodonta. ''Tikitherium'' refers to Tiki, the village located near the Tiki Formation where the specimen was found, and ''therium'' is Greek for “Beast”. The species was named ''copei'' in honor of Edward Drinker Cope for his pioneering discoveries towards understanding mammalian molars.Datta, P.M. 2005. Earliest Mammal with Transversely Expanded Upper Molar from the Late Triassic (Carnian) Tiki Formation, South Rewa Gondwana Basin, India. Journal of Vertebrate Paleontology. 25(1):200-207. History and discovery ''Tikitherium copei'' was first described by Datta in 2005. The first and only specimen is an upper left molar that was discovered in the lower part of the Tiki Formation, located in the South Rewa Gondwana Basin, India. Both the genus ''Tikitherium'' and the species ''copei'' were named by Datta in 2005. The currently only known spe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
