Smiling assassins - Anteosaurs

A selection of the extinct carnivorous dinocephalian therapsids known as anteosaurs, to scale.

During the Middle Permian there was a major change within the large terrestrial animals. Gone were the early pelycosaurs such as the predatory sphenacodonts and the herbivorous edaphosaurids and caseids, to be replaced by the early therapsids known as the dinocephalians. Although they never left any direct descendents, dinocephalians evolved into a diverse group of herbivores, carnivores and omnivores. Many species are known for thickened skulls with added bony projections which were probably used for territorial head-butting. Anteosaurs were the major predators during the Middle Permian, preying on their herbivorous relatives in addition to reptiles and amphibians. An upturned mouth, robust jaw and sharp teeth distinguish anteosaurs from any relatives. The hip joints are comparable to crocodiles, thus anteosaurs would have shown a semi-sprawling locomotion, witha suggestion of being semi-aquatic ambush predators. At 5-6 metres long, Anteosaurus is the largest known carnivorous synapsid, not including mammals.