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!"

South Africa has abundant fossil strata covering the Permian and Triassic Periods, but very little after that. The Jurassic of South Africa is only known from a group of sedimentary rocks called the Elliot Formation, just below the basalt of the Drakensberg, in what is known as the Stormberg Group. These rocks are in the northeast corner of the Eastern Cape, the eastern Free State, and the country of Lesotho that is completely enclosed in South Africa. The only jurassic fossils are known from the upper part of this group, and they cover the early Jurassic, about 190 million years ago, a period that is globally not well-represented.

These were early days for dinosaurs, and indeed the dinosaurs back then were not yet the giants they became soon after in the middle Jurassic and later. So we see in South Africa some of the precursors of the very biggest of the dinosaurs, the Sauropods. These include the well-known Brontosaurus (which for a long time was synonymised with Apatosaurus), Diplodocus and Brachiosaurus. The biggest sauropods reached over 30 m/100' in length, and approached 100 tons in weight (compared to 6 tons for a big, bull African bush elephant). But back in the early Jurassic, the precursors of these behemoths were typically 'only' about 4 to 10 m in length, and weighing half a ton to a few tons. The very early ones also were bipedal, and lightly built! As they grew bigger, they soon became too heavy to walk on hind legs alone, and dropped down to all fours. The nice thing is that the fossils from South Africa actually show this transition as it happened!

So let us start with Massospondylus, or 'Longer Vertebra'. It was from 4 to 6 m in total length, weighing up to a ton. This beastie is one of the first dinosaurs to be discovered in South Africa, and similar critters have been found in North and South America and Europe, from around the same time. It already had the long neck and somewhat small head associated with the latest sauropods, but it was bipedal. Indeed it could not use its forelimbs for walking, since its palms were turned inward, so it couldn't straighten them to put them flat on the ground. The first digit of the 'hand', that is to say the thumb, had a huge, curved claw. This could have been used for self-defense, for fighting against other Massospondyluses (maybe the males), for digging out roots and tubers, or for something else. Likely primarily a vegetarian, Massospondylus might have eaten at least some animal food also.

Massospondylus eggs have been found, the oldest dinosaur eggs ever discovered! And they contained bones of the embryos at near-hatching time! Here you can see a little one next to the big one - the 'top' one is actual size compared to the adult, but I blew it up below so you can better see what it looked like. The babies were indeed quadrupedal, and had comparatively larger heads and shorter necks, and with large eyes, must have been quite cute! It's possible that they were cared for by the adults, at least for a short period.

Aardonyx ('Earth Claw') was similar to Massospondylus, but while it usually walked on the hind legs, its forelimbs had the flexibility to allow it to turn the hands palms downward so it could use them for walking. It also had the great, curved claw on the 'thumb'. It was heavier of body than Massospondylus, and reached over 7m in length. The fossils we know were of immatures aged about 10 years. It likely could live a lot longer than that, and probably grew a bit more, though it grew fastest in its younger years. It had a wide gape, allowing it to rapidly ingest lots of leaves and other vegetable matter. This, too, was an adaptation towards the 'bulk feeding' methods of the later, larger sauropods.

Antetonitrus ('Before Thunder' that is to say earlier than the thunder-lizard Brontosaurus) was bigger still, and could only walk on all fours. The fossils we found were of sub-adults and it likely reached over 10 m in length as an adult, and weighed 5-6 tons. Its vertebrae had long spines to stiffen and strengthen the back. The arms were comparatively longer compared to the legs, and the wrist bones were strong to allow quadrupedal walking. But it still had the thumb claw, and could still use its hands to grasp, perhaps being able to rear onto its hind legs and support itself with its tail while feeding.

Melanorosaurus ('Black Mountain Lizard') was also quadrupedal, but perhaps slightly more primitive than Antenotritus and indeed may have lived in the late Triassic rather than the early Jurassic. It reached at least 8 m - some sources say as much as 15 m - and weighed a ton and a half, or more.

Just a final notice for anyone seeking more info about these dinos - there now exists some absolutely atrocious AI-generated content online that has computer-generated images that look nothing like the dinosaur they're supposed to represent, coupled with equally atrocious and entirely fictitious AI-generated info as well. Take care!

Willem

30.09.24 Front Page

Back Issue Page