1. Lycaenops 2. Eotitanosuchus 3. Gorgonops 4. Estemmenosuchus
Among the largest carnivorous synapsids were the therapsids Anteosaurus, which was 5–6 meters long, and weighed 500–600 kg
Anteosaurus (meaning "Antaeus reptile") is the name given to an extinct genus of large carnivorous synapsid. It lived during the Capitanian epoch of the Middle Permian (266-260 million years ago) in what is now South Africa. They became extinct by the middle Late Permian.
Anteosaurus was a semiaquatic synapsid with a long tail and weak limbs, which indicate a lifestyle including water, much like that of a crocodile. Anteosaurus was estimated to be over 5 metres (16 ft) long.Its most notable characteristic is its tall, narrow skull, which is 80 centimetres (31 in) long. The size of the skull is used to determine the age of a fossil. The teeth are another identifying characteristic of Anteosaurus. The teeth on the roof of the mouth are enlarged and confined in a cluster near the outer tooth row. The "normal teeth" include the anterior, canine and cheek teeth. A prominent feature of the dinocephalians is the ledge on the anterior teeth. The canine teeth are big, and there are usually about ten cheek teeth present. The front of the mouth curves up due to the premaxillary bone of the upper jaw. Paleontologists believe the presence of pachyostosis (thickening of the roof of the head) indicates a "head-butting" behavior of these dinocephalians, probably for protecting territory and fighting over a mate. This feature indicates that they were active on land as well.
The skull of a young Anteosaurus was found in Eastern Cape Province, South Africa where many skull fragments have been discovered relating to the dinocephalians. While four other Anteosauridae were found in the Isheevo region, Anteosaurus was the only anteosaurid predator in the South African temperate zone.
The ancestors of early therapsids from the late Permian include Struthiocephalus and Tapinocaninus. These therapsids are classified by their skull pachyostosis, body size, and herbivory. Five other genera of Anteosauridae are related to Anteosaurus: Australosyodon, Micranteosaurus (considered a "young" anteosaurus because of its small size), Paranteosaurus, Sinophoneus and Titanophoneus. There are 16 well-preserved skulls of Anteosaurus, 10 of which have been named as species of Anteosaurus, and are distinguished by their skull size and shape, number size and shape of teeth. The primitive skull and canine teeth are a distinctive characteristic of the Anteosaurus, which were passed on to its later descendants such as the Titanosuchidae, many of which changed their dietary habits to become omnivores or herbivores. The giant Anteosaurus is known to have existed at the same time that Titanophoneus and Doliosauriscus dominated in the Isheevo region. The family Anteosauridae replaced the Eotitanosuchidae, but were replaced in turn by large gorgonopsids.Ivantosaurus, with a length of 20 feet (6.1 meters). Eotitanosuchus known from a single large skull without a lower jaw.Skull 35 cm, overall length may have been over 2.5 meters.Like Biarmosuchus tener, it was primitive in that, though it was a predator, the temple opening behind the eye was small, giving it a weak bite. The temple was, however, larger at the top than in the biarmosuchians.
Eotitanosuchus fossils were found in the Perm (or Cis-Urals) region of Russia.Eotitanosuchus was without doubt a dominant animal of its environment. Found preserved in flood deposits (once coastal bogs) containing many skeletons of estemmenosuchids, it has been suggested that this large predator was an excellent swimmer, possibly semi-aquatic or frequenting marshy ground. This however is just speculation.
Eotitanosuchus is often grouped with the Phthinosuchidae and the Biarmosuchidae.In fact, Ivakhnenko (1999) argues that Biarmosuchus tener and Eotitanosuchus olsoni are the same organism, which would eliminate the Eotitanosuchia as a separate taxon,this conclusion does not seem to have been widely accepted.Regardless of the eventual outcome of this debate, Ivakhnenko's paper does seem to show that Eotitanosuchus is very similar to Biarmosuchus.Further, given the rather close similarity between Eotitanosuchus and later therapsids, this observation supports the view that Biarmosuchia is paraphyletic.Others view Eotitanosuchus as quite distinct from other basal therapsids and perhaps closer to the Gorgonopsia but gorgonopsian specializations are either not present in Eotitanosuchus or, as is more often the case, the state of the characters is unknown. This genus is characterized by many primitive features of the septomaxilla, the postorbital, the parietal, the interparietal, the basioccipital, the quadrate rami of the pterygoid and the vomers of the skull. The length of the dorsal process of the premaxilla (front jawbone) and the postorbital twisting (rear side of the skull) constitute specializations that indicate it is not a direct gorgonopsian ancestor. These features however are shared by the anteosaur and biarmosuchid lineages.
Gorgonopsia ("Gorgon face") is an extinct suborder of therapsid synapsids. Like other therapsids, gorgonopsians (or gorgonopsids) were at one time called "mammal-like reptiles" as well as "stem mammals".
Their mammalian specializations include differentiated (heterodont) tooth shape, a fully developed temporal fenestra, pillar-like rear legs, a vaulted palate that may have facilitated breathing while holding the prey, and incipiently developed ear bones. Gorgonopsians are a part of a group of therapsids called theriodonts, which includes mammals. They were among the largest carnivores of the late Permian. The largest known, Inostrancevia, was the size of a large bear with a 45 cm long skull, and 12 cm long saber-like teeth (clearly an adaptation to being a carnivore). They likely did not have a full pelage, but whether they had bristles, scales or naked skin is unknown. They possibly had a combination of all of them, as some mammals still do. Like most therapsids, they are assumed to have been terrestrial, and this is supported both by their morphology and bone microanatomy.
Gorgonopsians are theriodonts, a major group of therapsids that included the ancestors of mammals. They evolved in the Middle Permian, from a reptile-like therapsid that also lived in that period. The early gorgonopsians were small, being no larger than a dog. The extinction of dinocephalians (which dominated the Middle Permian world) led to gorgonopsids becoming the apex predators of the Late Permian. Some had approached the size of a rhinoceros, such as Inostrancevia, the largest gorgonopsian. A nearly complete fossil of Rubidgea has been found in South Africa. The Gorgonopsia became extinct at the end of the Permian period, being the only theriodont line to be terminated by this mass extinction.
The species in Inostrancevia were the largest gorgonopsids known, known individuals have total body lengths reaching up to 3.5 m (11.5 ft) and long, narrow skulls up to 60 cm (24 in) long. Like several other gorgonopsids, Inostrancevia was characterized by strongly developed canine teeth, with those of the upper jaw up to 15 cm (5.9 in) long, the root corresponding to half its length. Their bodies were slender, with rather short legs.
The genus Inostrancevia is one of if not the largest gorgonopsid to every walk the Earth. At up to three and a half meters long there is little doubt that Inostrancevia would have been the apex predator of its environment, hunting other large vertebrates which may have included large and armoured pareiasaurs such as Scutosaurus. As would be the expected the skull is large and robustly constructed with upper canine teeth that grew up to fifteen centimetres long. It is the combination of the teeth and skull mounted on a powerful body that may have been the key to defeating the armour of such prey.