Anteosaurus (meaning "Antaeus reptile") is an extinct genus of large carnivorous dinocephalian synapsid. It lived at the end of the Guadalupian (= Middle Permian) during the Capitanian stage, about 265 to 260 million years ago in what is now South Africa. It is mainly known by cranial remains and few postcranial bones. With its skull reaching in length and a body size estimated at more than in length, and in weight, 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 like the giants titanosuchids and tapinocephalids dinocephalians and large pareiasaurs.
As in many other dinocephalians the cranial bones of Anteosaurus are pachyostosed, but to a lesser extent than in tapinocephalid dinocephalians. In Anteosaurus, pachyostosis mainly occurs in the form of horn-shaped supraorbital protuberances. According to some paleontologists this structure would be implicated in intraspecific agonistic behaviour, including head-pushing probably during the mating season. On the contrary, other scientists believe that this pachyostosis served to reduce cranial stress on the bones of the skull when biting massive prey.
Young Anteosaurus started their life with fairly narrow and lean skulls, and as it grew up bones of the skull became progressively thickened (process known as pachyostosis), creating the characteristic robust skull roof of Anteosaurus. The study of its inner ear revealed that Anteosaurus was a largely terrestrial, agile predator with highly advanced senses of vision, balance and coordination. It was also very fast and would have been able to outrun competitors and prey alike thanks to its advanced adaptations. Its body was well-suited to projecting itself forward, both in hunting and evidently in head-butting.
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 the extinction of dinocephalian and an important volcanism event in China (known as the Emeishan Traps).
Etymology
Some confusion surrounds the etymology of the name Anteosaurus. It is often translated as meaning "before lizard", "previous lizard" or "primitive lizard", from the Latin prefix ante which means "before". The zoologist and paleontologist David Meredith Seares Watson gave no explanation when he named Anteosaurus in 1921. According to Ben Creisler, the prefix does not come from the Latin ante, but would refer to a Giant of the Greek mythology, Antaios, which once Latinized give Antaeus or more rarely Anteus. The type specimen of Anteosaurus is an incomplete skull that Watson had initially classified in the genus Titanosuchus, named after the Titans of the Greek mythology. Once this specimen recognized as belonging to a different genus, the name dedicated to Antaeus established another connection with a giant of Greek mythology.
Description
Size
Anteosaurus is one of the largest known carnivorous non-mammalian synapsid and anteosaurid, estimated to have reached more than in length, and a body mass of about . Juvenile specimen BP/1/7074 has an estimated body mass of about , showing extreme disparity in size with adult Anteosaurus.