Traditionally restored as scaly and purely reptilian and called “mammal-like reptiles”, they were theriodonts, of which mammals are the only living members. It is still unknown if they had hair, though. In life they would have seemed like a cross between a tyrannosaur and a saber-toothed cat, a strange yet successful combination.
Their entrance into the public consciousness was rather recent. The Gorgonopsia were made famous through the BBC show ‘Walking with Monsters’, in which a large individual is shown trying to survive through the oncoming climatic catastrophes at the end of the Permian. Their name was coined by Lydekker in 1890 for the purpose of classifying the holotype of Gorgonops, a rather medium-sized genus from the Karoo Basin of South Africa. Gorgonops is pretty much the archetype and the body plan that all gorgonopsians follow, with small differences in head shape, number and shape of teeth and other factors.
The Karoo, home of Gorgonops is essentially the story of the mid-to-late Permian Period all in one fossil bed, and even includes the beginnings of the Triassic in its uppermost reaches. The oldest units of the Karoo are more than 265 million years in age while the youngest are 20 million years younger. Gorgonops and its cousins are known from the second bed all the way to the last of the Late Permian beds. The gorgonopsians on the whole were part of a faunal empire, many of which lasted for a short interval of geological time, only to be replaced by another of their group.