Colours of Wildlife Extra: Thrinaxodon
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!"
Thrinaxodon was what was once called a 'mammal-like reptile' but actually it's much closer to mammals than to any reptile. A technical term for it would be a 'pre-mammalian synapsid' or pre-mammal. It was one of the great pioneers! A cynodont, its ancestors survived the end-Permian mass extinction; in time it ranged from about 251-247 million years ago. Warm-blooded and furry (as some of the Permian synapsids were as well) it likely had sensitive whiskers; it was a burrower, and the improved sense of touch would have helped it navigate its burrows. Its ribs were differentiated: long in the front and short or absent in the back of its torso. This means it might have had a diaphragm, helping it breathe more efficiently. It also had rib plates that would have reinforced its ribcage. Yet, its torso was flexible so that it could curl up in its burrows and put its nose between its rear legs to keep it warm! Thrinaxodon also had a secondary bony palate, which means it could breathe while it was eating. Its teeth were also differentiated: incisors in front, enlarged canines, and molar-type teeth at the rear. These were still simple, mostly with three cusps, and they didn't occlude precisely. Still, they would have helped it chew well. It was likely a hunter of small creatures. Studies of its bones indicate it grew fast when young, then its growth slowed down or stopped. Its inner and middle ear regions continued to develop towards the mammalian condition - its quadrate and articular jaw bones continued getting smaller and in true mammals would eventually detach from the jaw articulation and become tiny sound-transmitting bones, the malleus and the incus.
Thrinaxodon was about the size of a large cat. Its fossils were found in South Africa and Antarctica - indeed, this occurrence was used to prove that Africa and Antarctica used to be joined, giving evidence for continental drift.
An interesting and endearing find was of an early amphibian, Broomistega, inside a burrow with a Thrinaxodon. It had been bitten in its head and legs, but not by a Thrinaxodon. So apparently this amphibian sought the burrow of the Thrinaxodon as a shelter to recuperate in. The Thrinaxodon tolerated it and lay down next to it. The amphibian might have healed from its injury if whatever catastrophe killed the both of them hadn't happened, leading to their preservation and fossilisation.