Anteosaurus

Anteosaurus is an extinct genus of large carnivorous dinocephalian synapsid. It lived at the end of the Guadalupian (Middle Permian) during the Capitanian age, about 265 to 260 million years ago, in what is now South Africa. It is mainly known from cranial remains and few postcranial bones. Measuring 5–6 m (16–20 ft) long and weighing about 600 kg (1,300 lb), Anteosaurus was the largest known carnivorous non-mammalian synapsid and the largest terrestrial predator of the Permian period. Occupying the top of the food chain in the Middle Permian, its skull, jaws and teeth show adaptations to capture large prey, such as giant titanosuchid and tapinocephalid dinocephalians and large pareiasaurs.

As in many other dinocephalians the cranial bones of Anteosaurus are pachyostosed (thickened), but to a lesser extent than those of tapinocephalid dinocephalians. In Anteosaurus, pachyostosis mainly occurs in the form of supraorbital protuberances, the horn- or boss-shaped prominences above the eyes. According to some paleontologists this structure would be implicated in intraspecific agonistic behaviour, including head-pushing, probably to compete with conspecifics over mating rights during the mating season. On the contrary, other scientists believe that these adaptations served to reduce cranial stresses on the bones of the skull during predation. Young Anteosaurus had fairly narrow and lean skulls, with the bones of their skull becoming progressively more pachyostosed as they grew, forming the characteristic robust skull roof of the genus.

The study of its inner ear revealed that Anteosaurus was a largely terrestrial, agile predator with highly advanced senses of vision, balance, and coordination. These studies also suggested that Anteosaurus were quite fast and would have been able to outrun competitors and prey alike. Its body was well-suited to projecting itself forward, both in hunting and competition with others. Some researchers have at times proposed a semi-aquatic lifestyle for this animal.

Anteosaurus and all other dinocephalians became extinct about 260 million years ago in a mass extinction at the end of the Capitanian, in which the large Bradysaurian pareiasaurs also disappeared. The reasons of this extinction are obscure, although some research have shown a temporal association between an important volcanism event in China (known as the Emeishan Traps) and the extinction of dinocephalians.