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Hadrocodium Wui
''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 ca ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sinemurian
In the geologic timescale, the Sinemurian is an age and stage in the Early or Lower Jurassic Epoch or Series. It spans the time between 199.3 ± 2 Ma and 190.8 ± 1.5 Ma (million years ago). The Sinemurian is preceded by the Hettangian and is followed by the Pliensbachian. In Europe the Sinemurian age, together with the Hettangian age, saw the deposition of the lower Lias, in Great Britain known as the Blue Lias. Stratigraphic definitions The Sinemurian Stage was defined and introduced into scientific literature by French palaeontologist Alcide d'Orbigny in 1842. It takes its name from the French town of Semur-en-Auxois, near Dijon. The calcareous soil formed from the Jurassic limestone of the region is in part responsible for the character of the classic Sancerre wines. The base of the Sinemurian Stage is at the first appearance of the ammonite genera ''Vermiceras'' and '' Metophioceras'' in the stratigraphic record. A global reference profile ( GSSP or golden spike) for ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Crown Group
In phylogenetics, the crown group or crown assemblage is a collection of species composed of the living representatives of the collection, the most recent common ancestor of the collection, and all descendants of the most recent common ancestor. It is thus a way of defining a clade, a group consisting of a species and all its extant or extinct descendants. For example, Neornithes (birds) can be defined as a crown group, which includes the most recent common ancestor of all modern birds, and all of its extant or extinct descendants. The concept was developed by Willi Hennig, the formulator of phylogenetic systematics, as a way of classifying living organisms relative to their extinct relatives in his "Die Stammesgeschichte der Insekten", and the "crown" and "stem" group terminology was coined by R. P. S. Jefferies in 1979. Though formulated in the 1970s, the term was not commonly used until its reintroduction in 2000 by Graham Budd and Sören Jensen. Contents of the crown gr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Traversodontidae
Traversodontidae is an extinct family of herbivorous cynodonts. Traversodonts were primarily Gondwanan, with many species known from Africa and South America. Recently, traversodonts have also been found from Europe and eastern North America. Traversodonts first appeared in the Middle Triassic and diversified in the Late Triassic before going extinct at the end of the epoch. The family Traversodontidae was erected by Friedrich von Huene in 1936 for cynodonts first found in São Pedro do Sul in Paleorrota, Brazil. Description Traversodonts are members of Gomphodontia, a group of herbivorous cynognathian cynodonts. As an adaptation toward eating plants, they have wide postcanine teeth behind large canines. These postcanines are closely spaced with their crowns touching each other. Each is usually wider than it is long and is covered in several cusps. Because of their complexity, postcanine teeth are the primary means of identifying and distinguishing different species of traverso ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tritylodontidae
Tritylodontidae ("three-knob teeth", named after the shape of their cheek teeth) is an extinct family of small to medium-sized, highly specialized mammal-like cynodonts, bearing several mammalian traits like erect limbs, endothermy and details of the skeleton. They were the last-known family of the non-mammaliaform synapsids, persisting into the Early Cretaceous. Most tritylodontids are thought to have been herbivorous, feeding on vegetation, such as stems, leaves, and roots, although at least one may have had a more omnivorous diet. Tritylodontid fossils are found in the Americas, South Africa, and Eurasia—they appear to have had an almost global distribution, including Antarctica. Description The skull of tritylodontids had a high sagittal crest. They retained the primitive condition of the joint between the quadrate bone of the skull and the articular bone of the lower jaw—the retention of the joint is one of the reasons they are technically regarded to not be mam ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cynognathus
''Cynognathus'' is an extinct genus of large-bodied cynodontian therapsids that lived in the Middle Triassic. It is known from a single species, ''Cynognathus crateronotus''. ''Cynognathus'' was a long predator closely related to mammals and had a southern hemispheric distribution. Fossils have so far been recovered from South Africa, Argentina, Antarctica, and Namibia. Description ''Cynognathus'' was a heavily built animal, and measured around in snout-to-vent body length. It had a particularly large head, up to in length, with wide jaws and sharp teeth. Its hindlimbs were placed directly beneath the body, but the forelimbs sprawled outwards in a more reptilian fashion. This form of double (erect/sprawling) gait is also found in some primitive mammals alive today. Possible autapomorphies of ''C. crateronotus'' include an extremely elongated postorbital bar and sectorial postcanine teeth with two serrated cusps distal to a recurved apex. Discovery and naming During 18 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Eucynodontia
Eucynodontia ("true dog teeth") is a clade of cynodont therapsids including mammals and most non-mammalian cynodonts. The oldest eucynodonts are known from the Early Triassic and possibly Late Permian. Eucynodontia includes two major subgroups, Cynognathia and Probainognathia. The clade was named in 1982 by Thomas Kemp, who defined it as all cynodonts more derived than ''Thrinaxodon''. In 2001, Hopson and Kitching redefined the clade Eucynodontia as the least inclusive group containing Mammalia and ''Exaeretodon ''Exaeretodon'' is an extinct genus of fairly large, low-slung traversodontid cynodonts from the southern parts of Pangea. Four species are known, from various formations. ''E. argentinus'' is from the Carnian-age (Late Triassic) Cancha de Boch ...''.James A. Hopson and James W. Kitching, 2001, "A Probainognathian Cynodont from South Africa and the Phylogeny of Nonmammalian Cynodonts" pp 5-35 in: PARISH A. JENKINS, JR., MICHAEL D. SHAPIRO, AND TOMASZ OWERKOWICZ, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Thrinaxodon
''Thrinaxodon'' is an extinct genus of cynodonts, most commonly regarded by its species ''T. liorhinus'' which lived in what are now South Africa and Antarctica during the Early Triassic. ''Thrinaxodon'' lived just after the Permian–Triassic mass extinction event, its survival during the extinction may have been due to its burrowing habits. Similar to other therapsids, ''Thrinaxodon'' adopted a semi-sprawling posture, an intermediary form between the sprawling position of basal tetrapods (still observed modern Crocodilia) and the more upright posture present in current mammals.Blob R. 2001. Evolution of hindlimb posture in non-mammalian therapsids: biomechanical tests of paleontological hypotheses. 27(1): 14-38. ''Thrinaxodon'' is prevalent in the fossil record in part because it was one of the few carnivores of its time, and was of a larger size than similar cynodont carnivores. Description ''Thrinaxodon'' was a small synapsid roughly the size of a fox and possibly covered ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Epicynodontia
Epicynodontia is a clade of cynodont therapsids that includes most cynodonts, such as galesaurids, thrinaxodontids, and Eucynodontia (including mammals). It was erected as a stem-based taxon by Hopson and Kitching (2001) and defined as the most inclusive clade containing Mammalia and excluding ''Procynosuchus'', a Late Permian genus that is one of the most basal cynodonts. Below is a 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 ... from Ruta, Botha-Brink, Mitchell and Benton (2013) showing one hypothesis of cynodont relationships: References Cynodonts Lopingian first appearances Extant Permian first appearances Tetrapod unranked clades Taxa named by James Hopson Taxa named by James Kitching {{Therapsid-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Procynosuchidae
Procynosuchidae is an extinct family of therapsids which, along with Dviniidae, were the earliest cynodonts. They appeared around 260 million years ago, and were most abundant during the latest Permian time (251 mya), shortly before the Permian-Triassic extinction event. Despite being the basal member of the cynodont clade, they already showed some of the advanced mammalian characteristics, but Procynosuchids bore resemblance to the Therocephalians. Procynosuchid eyes are forward-facing, and the dentary was larger than the Therocephalians. The Procynosuchids had a secondary palate, which allows them to eat food while breathing, just like mammals. The Procynosuchids became extinct at the Permian-Triassic extinction event. Some procynosuchids were terrestrial, but others like ''Procynosuchus ''Procynosuchus'' (Greek: "Before dog crocodile") is an extinct genus of cynodonts from the Late Permian. It is considered to be one of the earliest and most basal cynodonts. It was 60& ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dvinia
''Dvinia'' is an extinct genus of cynodonts found in the Salarevo Formation of Sokolki on the Northern Dvina River near Kotlas in Arkhangelsk Oblast, Russia. It is the only known member of the family Dviniidae. Its fossil remains date from the Late Permian and were found with ''Inostrancevia'', ''Scutosaurus'' and '' Vivaxosaurus''. ''Dvinia'' was a small omnivore possessing a large temporal opening typical of advanced therapsids, with a thin postorbital bar separating the eye from the muscle attachment. As a cynodont, it was closely related to mammals. The dentition consisted of a set of small incisors followed by 2 canines and 10-14 postcanines. See also * List of therapsids This list of therapsids is an attempt to create a comprehensive listing of all genera that have ever been included in the Therapsida excluding mammals and purely vernacular terms. The list includes all commonly accepted genera, but also genera tha ... References Further reading * Patricia ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nocturnal Animal
Nocturnality is an animal behavior characterized by being active during the night and sleeping during the day. The common adjective is "nocturnal", versus diurnal meaning the opposite. Nocturnal creatures generally have highly developed senses of hearing, smell, and specially adapted eyesight. Some animals, such as cats and ferrets, have eyes that can adapt to both low-level and bright day levels of illumination (see metaturnal). Others, such as bushbabies and (some) bats, can function only at night. Many nocturnal creatures including tarsiers and some owls have large eyes in comparison with their body size to compensate for the lower light levels at night. More specifically, they have been found to have a larger cornea relative to their eye size than diurnal creatures to increase their : in the low-light conditions. Nocturnality helps wasps, such as ''Apoica flavissima'', avoid hunting in intense sunlight. Diurnal animals, including squirrels and songbirds, are active duri ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
