Anteosauria

'' The Anteosauria are distinguished from the Tapinocephalia by several features, such as very large canines, cheek teeth with bulbous crowns, and an upturning of the premaxilla, so that the front of the mouth curves strongly upwards. There is a tendency especially in more advanced forms such as Anteosaurus towards thickening of the bones of the top of the skull, indicating head-butting behavior. There is a large canal for the pineal organ (third eye); probably tied in with the animal's diurnal and seasonal cycles. The shoulder girdle is fairly light, with a narrow interclavicle, clavicle, and scapular blade. The femur (thigh bone) is slender and curved. These were, despite their size, probably quite agile animals. The limbs are short and the skull is long, narrow, and heavy. The tail is very long in at least some genera. ==Classification ==

Evolutionary relationships Initially, it has been suggested that the estemmenosuchids are the most basal of the dinocephalians. However, most experts now recover anteosaurs as the most basal of the dinocephalians, with the Russian anteosaurs considered the clade. They have featured in common with pelycosaurs (Carroll 1988) and biarmosuchians (Chudinov 1965), and, with the tapinocephalians, are part of the first major evolutionary radiation of the therapsids. }} }} }} Taxonomy The group name Anteosauria was first used by L. D. Boonstra in 1955 to include the families Brithopodidae and Anteosauridae. In his 1988 review, Gillian King named the superfamily Anteosauroidea to include the following families, in which the "Titanosuchidae" being equivalent to the "Tapinocephalia". • Superfamily Anteosauroidea Boonstra, 1962 • Family Brithopidae Boonstra, 1972 • Subfamily Brithopodinae Efremov, 1954 • Subfamily Anteosaurinae Boonstra, 1954 • Family Titanosuchidae Boonstra, 1972 • Subfamily Titanosuchinae Broom, 1903 • Subfamily Tapinocephalinae Lydekker, 1890 After Kammerer et al. (2011): • Class Synapsida • Order Therapsida • Suborder Dinocephalia • Clade Anteosauria • Family Anteosauridae • Archaeosyodon • Microsyodon • Subfamily Anteosaurinae • Sinophoneus • Titanophoneus • Anteosaurus • Subfamily Syodontinae • Australosyodon • Notosyodon • Pampaphoneus • Syodon • Family Brithopodidae • Admetophoneus • Brithopus • Chthomaloporus • Eosyodon • Mnemeiosaurus • Family Deuterosauridae • Deuterosaurus ==Palaeobiology==

Ecology of Anteosaurus feeding on an Estemmenosuchus'' The stance of a typical anteosaur, such as Titanophoneus, was primitive. Rather than the limbs being drawn in under the body, the stance was more sprawling. Olson (1962) notes that the Russian dinocephalian assemblages indicate environments tied to water, and Boonstra considered that the roughly contemporary Anteosaurus was a slinking crocodile-like semi-aquatic form. The long tail, weak limbs, and sprawling posture do indeed suggest some sort of crocodile-like existence. However, the thickened skull-roof indicates that these animals were quite able to get about on land, if they were to practice the typically dinocephalian head-butting behavior. All other head-butters, pachycephalosaurian dinosaurs, titanothere ungulates, and goats were or are completely terrestrial. Bhat et al. (2021) suggested that Anteosaurus may have occasionally inhabited shallow and short-lived pools, similar to modern day hippopotamus, based on its bone histology. Feeding Anteosaurs were evolved to prey on particularly large animals and were among the most highly predaceous of all synapsids (Sennikov, 1996), potential prey included the bull-sized armored pareiasaurs (Lee, 1997) and enormous tapinocephalid dinocephalians (Rubidge, 1995). The large anteosaurs were efficient predators, more specialized than earlier and more primitive biarmosuchid and eotitanosuchid carnivorous therapsids, as the temporal opening behind the eye socket was larger, indicating a greater muscle mass available for closing the lower jaw. Large pterygoid flanges indicate a well-developed Kinetic-Inertial system in anteosaurs, and increased vertical alignment of the temporalis muscles suggests an expanded Static-Pressure component of the bite cycle. ==References==