Gorgonopsians Part 1
Willem is a wildlife artist based in South Africa. He says "My aim is simply to express the beauty and wonder that is in Nature, and to heighten people's appreciation of plants, animals and the wilderness. Not everything I paint is African! Though I've never been there, I'm also fascinated by Asia and I've done paintings of Asian rhinos and birds as well. I may in future do some of European, Australian and American species too. I'm fascinated by wild things from all over the world! I mainly paint in watercolours. . . but actually many media including 'digital' paintings with the computer!"
We come to the second-to-last group of proto-mammals to be featured here – the Gorgonopsians. The name means 'gorgon-faced' and signifies the fearsome facial appearance of these old critters. If you don't know the story from Greek mythology, the gorgons were three sisters, the most famous of which was Medusa, who had snakes for hair and whose stare could turn people to stone. Now the real gorgonopsians likely didn't have snakes for hair, and they likely couldn't turn anyone to stone, but in the event their own faces turned to stone often enough to leave us with quite a diversity of well-preserved fossils. Gorgonopsians flourished in the middle to late Permian period, about 270-252 million years ago; they're known primarily from South Africa and Russia. In build, they were rather dog-like except for a slight splaying of the legs, the hind legs being a bit more upright than the front ones. They could run well, at least as fast as anything else alive at the time. Their tails were medium to short in length, fairly muscular. Their heads were proportionally large. Gorgonopsians were likely descended from early Biarmosuchians. They were mostly medium-sized to large, ranging from the size of a cat to that of a large tiger or bear. They specialized in overly long, stabbing canine teeth. They also had powerful and sharp front (incisor) teeth, but the teeth behind the canines were small, weak or sometimes absent. The idea is that they used their sabre-teeth to stab their victims to death, or to sever their neck arteries, and then fed by pulling the meat from the bones with their sharp front teeth, swallowing it in chunks without chewing.
The first gorgonopsians were small, about cat-sized. After the extinction of the Dinocephalians, the Therocephalians became for a short while the dominant large predators, but soon the gorgonopsians became much bigger, and dominated them towards the end of the Permian. But while therocephalians and cynodonts survived past the Permian, all the gorgonopsians died out at the end of that period. Their reign was brief but successful. There are indications that some of them were nocturnal, while others were clearly diurnal (active during the daytime).
Debate about the gorgonopsians basically revolves around whether they were furry, and whether their sabre teeth were exposed or concealed by big lips or skin-sheaths. They give the appearance of being active hunters, and thus there's support for them having fast metabolism and being warm-blooded, or in more scientific terms, endothermic. If so, they would have done well with furry, insulating coats. We have evidence that, in the late Permian, at least some critters did indeed have hair or fur, but we don't know which ones. Since the gorgonopsians were among the most advanced, mammal-like animals of the Permian, if anything was furry it was likely one of them. So, I'm reconstructing them with fur. I may prove wrong, of course, in which case I'd be happy to draw some new reconstructions!
The second question is whether their teeth really protruded from their mouths. In the 'old days' of paleo-art, things like dinosaurs and also many old things that were not dinosaurs, like these, were portrayed with minimal or no lips so that all their teeth remained visible even if their mouths were closed. Recently there's been a campaign of sorts in the paleo-art community to put lips on everything. There's been an argument advanced that teeth would for their own health need to be covered by lips most of the time so that they'd stay properly hydrated or 'moisturized' … the idea being that if they dried out they would have suffered damage like perhaps becoming brittle or splintering. But this argument doesn't hold for all teeth, and even today we have some sabre-toothed critters that have teeth permanently exposed … not just crocodiles, who go into the water often enough to keep their teeth hydrated, but also for instance musk deer. The group I've just finished with, the dicynodonts, also often had long canine teeth that must have remained exposed throughout their lives, since they had horny beaks rather than fleshy lips that might otherwise have covered their teeth. Similarly, we don't think that the many sabre-toothed cat species that lived all over the world until quite recently, all had long lip flaps with which to cover their teeth. The argument of long teeth necessarily having to remain covered with lips thus breaks down.
And the gorgonopsians certainly have immense sabre-like teeth. In many of the larger kinds, the upper canines protruded so far that their tips went beyond the margin of the lower jaw when their mouths were closed. They would have needed deep 'sheaths' of flesh in which to hide these. And they'd be in danger of piercing their own lips every time they closed their mouths. Also, like other proto-mammals, they didn't replace their teeth all at once like modern mammals do, but replaced them individually over a long period. New canine teeth emerged in front of or behind the old canines and at times, they might even have two functional canine teeth on each side of the upper jaw. So the lip-sheaths would have needed to be very commodious to accommodate not just the present pair of canines, but also a new pair that might emerge in front of or behind the old ones. And there is yet no evidence of these old things having extensive, mobile lips of the modern mammalian kind. We know these must have emerged over the course of proto-mammal evolution, since by about 200 million years ago, there were some that were suckling their young, and mobile lips help the babies to suck in the milk. But would that have been the case for the gorgonopsians, who lived fifty million years or more earlier than that? I am a bit doubtful. Consequently, I'm reconstructing my gorgonopsians with lips, but not extensive lip sheaths that would hide their long canine teeth, leaving them exposed as in other sabre-toothed critters.
Now for a few species. First of all I seem to be breaking my own rules, for here you see a painting of a Lycaenops ornatus ('ornate wolf-face', a dog-sized species from South Africa), that is smooth-skinned and that does not feature noticeable lips, leaving many of its upper teeth exposed. Well, that's because it's not my own reconstruction! This was painted by my father, Willem Petrus van der Merwe, many years ago when he was helping me with a book on dinosaurs and a few other prehistoric things. I didn't coach my dad much, just showing him the skeletons and a few reconstructions by other artists. I'm including it here as a tribute to him. In spite of inaccuracies, I think he did very well. His painting does show many of the features of the gorgonopsians, even in the skull, where apart from the teeth you can see the single opening (filled with jaw muscles) in the rear of the skull, which is the main feature uniting the proto-mammals with the true mammals. The ear opening is close to the hinge of the lower jaw. In the evolution of proto-mammals, through many stages, the rear of the lower jaw eventually became the mammalian ear. This will become evident when I get to the cynodonts, the group from which true mammals evolved. But the process of elaborating the bones at the rear of the jaw for the purpose of picking up and transmitting sound vibrations was already well under way in the gorgonopsians.
The next full-body illustration is my own. It shows Inostrancevia alexandri, 'Aleksandr Inostrantsev's critter', a species from the late Permian of Russia. Inostrantsev was a famous Russian geologist. Inostrancevia was one of the largest gorgonopsians, reaching a length of over 4 m/13', with a skull of 60 cm/2' in length. It likely preyed on large critters like the heavy-set reptilian Pareiasaurs, the biggest plant-eaters of the time. First discovered at the end of the Nineteenth Century, it is represented by well-preserved skulls as well as complete skeletal material. Here you see it reconstructed with shaggy fur, and powerful muscles.
The last one for now is Rubidgea atrox ('Rubidge's horrendous critter'). (Professor Bruce Rubidge is an active palaeontologist of the Karoo region.) This one lived in South Africa, also in the late Permian. It had a shorter skull than Inostrancevia, but was more sturdy and powerful in build. Its canine teeth were very long and sharp. It had a skull with a broadly flaring rear part and numerous thickenings, called 'bosses'. These may have been overlain by keratinous, horny pads, as I reconstruct it here. The bosses were over and to the rear of its eyes, at the back of the upper jaw, and at the sides of the lower jaw. They might have been for reinforcing the bone to give it a more powerful bite. It might have needed strong bones and muscles to restrain large and struggling prey. Rubidgea had eyes partly facing forward, giving it binocular vision.
In body build, this is about what all the gorgonopsians likely looked like. In Part 2 I will show you a few more facial reconstructions of some of the most well-known species.