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Therapsida
Therapsida is a clade comprising a major group of eupelycosaurian synapsids that includes mammals and their ancestors and close relatives. Many of the traits today seen as unique to mammals had their origin within early therapsids, including limbs that were oriented more underneath the body, resulting in a more "standing" quadrupedal posture, as opposed to the lower sprawling posture of many reptiles and amphibians. Therapsids evolved from earlier synapsids commonly called " pelycosaurs", specifically within the Sphenacodontia, more than 279.5 million years ago. They replaced the pelycosaurs as the dominant large land animals in the Guadalupian through to the Early Triassic. In the aftermath of the Permian–Triassic extinction event, therapsids declined in relative importance to the rapidly diversifying archosaurian sauropsids (pseudosuchians, dinosaurs and pterosaurs, etc.) during the Middle Triassic. The therapsids include the cynodonts, the group that gave rise to mammal ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Therocephalia
Therocephalia is an extinct clade of therapsids (mammals and their close extinct relatives) from the Permian and Triassic periods. The therocephalians ("beast-heads") are named after their large skulls, which, along with the structure of their teeth, suggest that they were carnivores. Like other non-mammalian synapsids, therocephalians were once described as "mammal-like reptiles". Therocephalia is the group most closely related to the cynodonts, which gave rise to the mammals. Indeed, it had been proposed that therocephalians themselves may have given rise to the cynodonts, and therefore that therocephalians as recognised are paraphyletic in relation to cynodonts and so not a clade. Conventionally, however, Therocephalia is regarded as the sister clade of Cynodontia, together forming the clade Eutheriodontia. The close relationship of Therocephalia to Cynodontia takes evidence in a variety of skeletal features. Most notable is that the skull roof is narrowed between two enlarged ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gorgonopsia
Gorgonopsia (from the Greek Gorgon, a mythological beast, and 'aspect') is an extinct clade of Saber-toothed predator, sabre-toothed therapsids from the Middle Permian, Middle to the Upper Permian, roughly between 270 and 252 million years ago. They are characterised by a long and narrow skull, as well as elongated upper and sometimes lower canine teeth and incisors which were likely used as slashing and stabbing weapons. Postcanine teeth are generally reduced or absent. For hunting large prey, they possibly used a bite-and-retreat tactic, ambushing and taking a debilitating bite out of the target, and following it at a safe distance before its injuries exhausted it, whereupon the gorgonopsian would grapple the animal and deliver a killing bite. They would have had an exorbitant gape, possibly in excess of 90°, without having to unhinge the jaw. They markedly increased in size as time went on, growing from small skull lengths of in the Middle Permian to bear-like proportions of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dicynodont
Dicynodontia is an extinct clade of anomodonts, an extinct type of non-mammalian therapsid. Dicynodonts were herbivores that typically bore a pair of tusks, hence their name, which means 'two dog tooth'. Members of the group possessed a horny, typically toothless beak, unique amongst all synapsids. Dicynodonts first appeared in Southern Pangaea during the mid-Permian, ca. 270–260 million years ago, and became globally distributed and the dominant herbivorous animals in the Late Permian, ca. 260–252 Mya. They were devastated by the end-Permian Extinction that wiped out most other therapsids ca. 252 Mya. They rebounded during the Triassic but died out towards the end of that period. They were the most successful and diverse of the non-mammalian therapsids, with over 80-90 genera known, varying from rat-sized burrowers to elephant-sized browsers. Characteristics The dicynodont skull is highly specialised, light but strong, with the synapsid temporal openings at the rear o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lycosuchid
Lycosuchidae is a Family (biology), family of therocephalians (an extinct type of therapsids, broader group which modern mammals belong to) known from fossils from what is now the Beaufort Group of South Africa and that lived during the Middle Permian, Middle to Late Permian between roughly 265 to 258 million years ago. It currently includes only two genera each with a single species, ''Lycosuchus'', represented by ''L. vanderrieti'', and ''Simorhinella'', represented by ''S. baini'', both named by paleontologist Robert Broom in 1903 and 1915, respectively (though ''Simorhinella'' was not recognised as a lycosuchid until 2014). Both species are large predators characterised by their size, reduced tooth counts with large, almost "Saber-toothed predator, sabre toothed" canine teeth, and relatively short, broad and low snouts. Lycosuchids were once thought to be defined by having two simultaneously functional pairs of canines, so-called "double canines", instead of a single pair of l ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Theriodontia
The theriodonts (clade Theriodontia) are a major group of therapsids which appeared during the Middle Permian and which includes the gorgonopsians and the eutheriodonts, itself including the therocephalians and the cynodonts. Naming In 1876, Richard Owen named a suborder Theriodontia, which he divided into the Cynodontia and the Gomphodontia. In 1956, D. M. S. Watson and Alfred Romer divided Therapsida into Theriodontia, which predominantly included carnivorous species, and the mostly herbivorous Anomodontia, defined as comprising Dinocephalia as well as Venyukovioidea and Dicynodontia. The modern clade concept was devised by James Allen Hopson. In his system, Theriodontia fall into two main groups: the Gorgonopsia and the Eutheriodontia. The latter consist of the Therocephalia and Cynodontia.J.A. Hopson. 1999. "Therapsids". ''Encyclopedia of Paleontology'' 2: 1256-1266 Evolution Theriodonts appeared at the same time as their sister group within the Neotherapsida, the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Biarmosuchia
Biarmosuchia is an extinct clade of non-mammalian synapsids from the Permian. Biarmosuchians are the most basal group of the therapsids. They were moderately-sized, lightly built carnivores, intermediate in form between basal sphenacodont " pelycosaurs" and more advanced therapsids. Biarmosuchians were rare components of Permian ecosystems, and the majority of species belong to the clade Burnetiamorpha, which are characterized by elaborate cranial ornamentation. Characteristics The biarmosuchian skull is very similar to the sphenacodontid skull, differing only in the larger temporal fenestra (although these are still small relative to later therapsids), slightly backward-sloping occiput (the reverse of the pelycosaur condition), reduced number of teeth, and single large canine teeth in both upper and lower jaws, and other features (Carroll 1988 pp. 370, Benton 2000 p. 114). In later specialised Biarmosuchia, these resemble the enlarged canines of the Gorgonopsia. T ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Raranimus
''Raranimus'' is an extinct genus of therapsids of the Middle Permian. It was described in 2009 from a partial skull found in 1998 from the Dashankou locality of the Qingtoushan Formation, outcropping in the Qilian Mountains of Gansu, China. The genus is the most basal known member of the clade Therapsida, to which the later Mammalia belong. Description ''Raranimus'' shares a number of features with later therapsids and ancestral Sphenacodontia. The skull consists of a well preserved rostrum. The teeth suggest a carnivorous lifestyle for ''Raranimus'', as the incisors are recurved and the second canines are serrated on their posterior edges. The incisors are morphologically similar to those seen in more derived theriodonts. The presence of two linguo−labially compressed canines is a diagnostic feature of ''Raranimus''. The presence of two functional canines is characteristic of sphenacodontids, and this condition is seen in no other therapsid other than ''Rananimus''. Howeve ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Synapsid
Synapsida is a diverse group of tetrapod vertebrates that includes all mammals and their extinct relatives. It is one of the two major clades of the group Amniota, the other being the more diverse group Sauropsida (which includes all extant reptiles and therefore, birds). Unlike other amniotes, synapsids have a single temporal fenestra, an opening low in the skull roof behind each eye socket, leaving a zygomatic arch, bony arch beneath each; this accounts for the name "synapsid". The distinctive temporal fenestra developed about 318 million years ago during the Late Carboniferous period, when synapsids and sauropsids diverged, but was subsequently merged with the orbit in early mammals. The basal (phylogenetics), basal amniotes (reptiliomorphs) from which synapsids evolved were historically simply called "reptiles". Therefore, stem group synapsids were then described as mammal-like reptiles in classical systematics, and non-therapsid synapsids were also referred to as pelyco ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Permian–Triassic Extinction Event
The Permian–Triassic extinction event (also known as the P–T extinction event, the Late Permian extinction event, the Latest Permian extinction event, the End-Permian extinction event, and colloquially as the Great Dying,) was an extinction event that occurred approximately 251.9 Million years ago, million years ago (mya), at the boundary between the Permian and Triassic geologic periods, and with them the Paleozoic and Mesozoic eras. It is Earth's most severe known extinction event, with the extinction of 57% of Family (biology), biological families, 62% of genera and 81% of marine biology, marine species, (previous estimates of 90–96% marine species extinction were due to historical conflation with the End-Capitanian mass extinction event, end-Capitanian mass extinction which occurred 7–10 million years earlier) and 70% of terrestrial vertebrate species. It is also the greatest known mass extinction of insects. It is the greatest of the "Big Five" mass extinctions of t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lystrosaurus
''Lystrosaurus'' (; 'shovel lizard'; proper Ancient Greek is ''lístron'' ‘tool for leveling or smoothing, shovel, spade, hoe’) is an extinct genus of herbivorous dicynodont therapsids from the late Permian and Early Triassic epochs (around 248 million years ago). It lived in what is now Antarctica, India, China, Mongolia, European Russia and South Africa. Four to six species are currently recognized, although from the 1930s to 1970s the number of species was thought to be much higher. They ranged in size from that of a small dog to 8 feet (2.5 meters) long. As a dicynodont, ''Lystrosaurus'' had only two teeth (a pair of tusk-like canines), and is thought to have had a horny beak that was used for biting off pieces of vegetation. ''Lystrosaurus'' was a heavily built, herbivorous animal. The structure of its shoulders and hip joints suggests that ''Lystrosaurus'' moved with a semi-sprawling gait. The forelimbs were even more robust than the hindlimbs, and t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Inostrancevia
''Inostrancevia'' is an extinction, extinct genus of large carnivorous therapsids which lived during the Late Permian in what is now European Russia and Southern Africa. The first-known fossils of this gorgonopsian were discovered in the context of a long series of excavations carried out from 1899 to 1914 in the Northern Dvina, Russia. Among these are two near-complete skeletons embodying the first described specimens of this genus, being also the first gorgonopsian identified in Russia. Several other fossil materials were discovered there, and the various finds led to confusion as to the exact number of valid species, before only two of them were formally recognized, namely ''I. alexandri'' and ''I. latifrons''. A third species, ''I. uralensis'', was erected in 1974, but the fossil remains of this taxon are very thin and could come from another genus. More recent research carried out in Southern Africa has discovered specimens identified as belonging to this genus, with the spec ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dinocephalia
Dinocephalians (terrible heads) are a clade of large-bodied early therapsids that flourished in the Early and Middle Permian between 279.5 and 260 million years ago (Ma), but became extinct during the Capitanian mass extinction event. Dinocephalians included herbivorous, carnivorous, and omnivorous forms. Many species had thickened skulls with many knobs and bony projections. Dinocephalians were the first non-mammalian therapsids to be scientifically described and their fossils are known from Russia, China, Brazil, South Africa, Zimbabwe, and Tanzania. Description Apart from the biarmosuchians, the dinocephalians are the least advanced therapsids, although still uniquely specialised in their own way. They retain a number of primitive characteristics (e.g. no secondary palate, small dentary) shared with their pelycosaur ancestors, although they are also more advanced in possessing therapsid adaptations like the expansion of the ilium and more erect limbs. They ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
