| Alopecorhinus | |
|---|---|
Scientific classification  | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Clade: | Therapsida |
| Suborder: | † Therocephalia |
| Family: | † Scylacosauridae |
| Genus: | † Alopecorhinus Broom, 1912 |
Alopecorhinus is an extinct genus of therocephalian therapsids.
| Alopecorhinus | |
|---|---|
| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Clade: | Therapsida |
| Suborder: | † Therocephalia |
| Family: | † Scylacosauridae |
| Genus: | † Alopecorhinus Broom, 1912 |
Alopecorhinus is an extinct genus of therocephalian therapsids.
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. They are easily separated from other amniotes by having 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. Synapsids evolved from basal amniotes and are one of the two major groups of amniotes, the other being the sauropsids, the group that includes reptiles and birds. The distinctive temporal fenestra developed in the ancestral synapsid about 312 million years ago, during the Late Carboniferous period.
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 earliest fossil attributed to Therapsida used to be Tetraceratops insignis from the Lower Permian. However in 2020, a new study has found that Tetraceratops is not actually a true Therapsid, but should be considered to be a member of the more ancient Sphenacodontia from which the Therapsids evolved.
The Eupelycosauria originally referred to a suborder of 'pelycosaurs', but has been redefined to designate a clade of synapsids that includes most pelycosaurs, as well as all therapsids and mammals. They first appear during the Early Pennsylvanian epoch, and represent just one of the many stages in the acquiring of mammal-like characteristics, in contrast to their earlier amniote ancestors. The defining characteristics which separate these animals from the Caseasauria are based on details of proportion of certain bones of the skull. These include a long, narrow supratemporal bone, and a frontal bone with a wider connection to the upper margin of the orbit.
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.
Tetraceratops insignis is an extinct synapsid from the Early Permian of Texas. It was originally classified as an early and very primitive member of Therapsida, a group that includes mammals and their close extinct relatives. However, it is now seen as a primitive non-therapsid sphenacodont rather than a genuine basal therapsid.
Phthinosuchus is an extinct genus of therapsids from the Middle Permian of Russia. Phthinosuchus is the sole member of the family Phthinosuchidae. Phthinosuchus may have been one of the most primitive therapsids, meaning that its ancestors may have branched off early from the main therapsid line.
Galechirus is an extinct genus of anomodont therapsids. It was about 30 cm (1 ft) long.
Nikkasaurus is an extinct genus of therapsids.
Galeops is an extinct genus of anomodont therapsids.
Eotitanosuchidae is an extinct family of biarmosuchian therapsids. The Eotitanosuchidae were large predatory therapsids of the Wordian epoch. It was once considered to belong to a separate infraorder of therapsids called Eotitanosuchia.
Biseridens is an extinct genus of anomodont therapsid, and one of the most basal anomodont genera known. Originally known from a partial skull misidentified as an 'eotitanosuchian' in 1997, another well-preserved skull was found in the Xidagou Formation, an outcropping in the Qilian Mountains of Gansu, China, in 2009 that clarified its relationships to anomodonts, such as the dicynodonts.
Cistecephaloides is an extinct genus of dicynodont therapsids of the Cistecephalus Assemblage Zone, Beaufort Group of South Africa.
Cerdodon is an extinct genus of gorgonopsian therapsids.
Dimacrodon is an extinct genus of non-mammalian synapsid from the latest Early Permian San Angelo Formation of Texas. It is distinguished by toothless, possibly beaked jaw tips, large lower canines and a thin bony crest on top of its head. Previously thought to be an anomodont therapsid related to dicynodonts, it was later found to lack any diagnostic features of anomodonts or even therapsids and instead appears to be a 'pelycosaur'-grade synapsid of uncertain classification.
Glanosuchus is a genus of scylacosaurid therocephalian from the Late Permian of South Africa. The type species G. macrops was named by Robert Broom in 1904. Glanosuchus had a middle ear structure that was intermediate between that of early therapsids and mammals. Ridges in the nasal cavity of Glanosuchus suggest it had an at least partially endothermic metabolism similar to modern mammals.
Mastersonia is an extinct genus of non-mammalian therapsids from the Lower Permian of San Angelo Formation, Texas.
Phreatosaurus is an extinct genus of basal dinocephalian therapsids.
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.
Macroscelesaurus is an extinct genus of therocephalian therapsid from the Late Permian of South Africa. The type species Macroscelesaurus janseni was named by Sidney H. Haughton in 1918 from the Cistecephalus Assemblage Zone. It is one of the few therocephalians known from postcranial remains.
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