| Colobodectes Temporal range: Middle Permian | |
|---|---|
Scientific classification  | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Clade: | Synapsida |
| Clade: | Therapsida |
| Clade: | † Dicynodontia |
| Genus: | † Colobodectes Modesto et al., 2003 |
| Type species | |
| †C. cluveri Modesto et al., 2003 | |
Colobodectes is an extinct genus of dicynodont therapsid from the Tapinocephalus Assemblage Zone in the Abrahamskraal Formation (Beaufort Group), South Africa. [1]
Synapsids are a group of animals that includes mammals and every animal more closely related to mammals than to the other members of the amniote clade, such as reptiles and birds. Unlike other amniotes, they have a temporal fenestra, an opening low in the skull roof behind each eye, leaving a bony arch beneath each; this accounts for their name. Primitive synapsids are usually called pelycosaurs or pelycosaur-grade synapsids. This informal term consists of all synapsids that are not therapsids, a monophyletic, more advanced, mammal-like group. The non-mammalian synapsids were described as mammal-like reptiles in classical systematics, but this misleading terminology is no longer in use as synapsids as a whole are no longer considered reptiles. They are now more correctly referred to as stem mammals or proto-mammals.
Therapsida is a major group of eupelycosaurian synapsids that includes mammals and their ancestors. 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, as opposed to the sprawling posture of many reptiles and salamanders.
The pelycosaurs were previously considered an order, but are now only an informal grouping composed of basal or primitive Late Paleozoic synapsids, formerly called mammal-like reptiles. They consist of all synapsids excluding the therapsids and their descendants.
Dinocephalia is a clade of large-bodied early therapsids that flourished for a brief time in the Middle Permian between 270 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.
Sphenacodontia is a stem-based clade of derived synapsids. It was defined by Amson and Laurin (2011) as "the largest clade that includes Haptodus baylei, Haptodus garnettensis and Sphenacodon ferox, but not Edaphosaurus pogonias". They first appear during the Late Pennsylvanian epoch. From the end of the Carboniferous to the end of the Permian, most of them remained large, with only some secondarily becoming small in size.
Eupelycosauria is a large clade of animals characterized by the unique shape of their skull, encompassing all mammals and their closest extinct relatives. They first appeared 308 million years ago during the Early Pennsylvanian epoch, with the fossils Archaeothyris and perhaps an even earlier genus, Protoclepsydrops, representing just one of the many stages in the evolution of mammals, in contrast to their earlier amniote ancestors.
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.
Ericiolacerta is an extinct genus of small therocephalian therapsids from the early Triassic of South Africa and Antarctica. It was around 20 centimetres (7.9 in) in length, with long limbs and relatively small teeth. It probably ate insects and other small invertebrates.
Therocephalia is an extinct suborder of eutheriodont therapsids from the Permian and Triassic. 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. This relationship takes evidence in a variety of skeletal features. The phylogeny of therocephalians has been disputed, as the monophyly of the group and the relationships of its members are unclear.
Tetraceratops insignis is an extinct synapsid from the Early Permian that may be the first known representative of Therapsida, a group that includes mammals and their close extinct relatives. It is known from a single 90-millimetre-long (3.5 in) skull, discovered in Texas in 1908. According to a 2020 study, it should be classified as a primitive non-therapsid sphenacodont rather than a genuine basal therapsid.
Anomocephalus is an extinct genus of primitive anomodonts and belongs to the clade Anomocephaloidea. The name is said to be derived from the Greek word anomos meaning lawless and cephalos meaning head. The proper word for head in Greek is however κεφαλή (kephalē). It is primitive in that it retains a complete set of teeth in both jaws, in contrast to its descendants, the dicynodonts, whose dentition is reduced to only a single pair of tusks, with their jaws covered by a horny beak similar to that of a modern tortoise. However, they are in no way closely related.
Brachyprosopus is an extinct genus of dicynodont therapsid from the middle Permian Tapinocephalus Assemblage Zone in the Abrahamskraal Formation belonging to the Beaufort Group of the Karoo Basin, South Africa.
Cistecephaloides is an extinct genus of dicynodont therapsids of the Cistecephalus Assemblage Zone, Beaufort Group of South Africa.
Dongusaurus is an extinct genus of therocephalian therapsids.
Ictidognathus is an extinct genus of therocephalian therapsids that lived in South Africa during the Late Permian. Fossils are found in the Tropidostoma and Cistecephalus Assemblage Zones of the Beaufort Group in the Western Cape.
Scylacorhinus is an extinct genus of therocephalian therapsids from South Africa.
Zorillodontops is an extinct genus of therocephalian therapsids from the Early Triassic of South Africa.
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 Xidagou 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.
The Eutheriodontia are a clade of therapsids that includes therocephalians and cynodonts.
Gorgodon is an extinct genus of basal synapsids. The genus is monotypic, known only from the type species Gorgodon minutus from the Early Permian of the southwestern United States. The only known remains of Gorgodon are two fossils consisting of fragments of the skull. Gorgodon was described and named by paleontologist Everett C. Olson in 1962 from the San Angelo Formation in Knox County, Texas. Based on what is known of Gorgodon—the squamosal, quadrate, and pterygoid bones of the back of the skull, the maxilla and premaxilla bones that make up the front of the skull, and several teeth—Gorgodon had a relatively large temporal fenestra and a pair large, conical caniniform teeth at the front of the jaw. Other distinguishing features of Gorgodon include the fused connection between the quadrate and squamosal bones and a long transverse process of the pterygoid.
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