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!"

I'm still with the illustrations I created for the Bishop Museum of Science and Nature. The Bishop Museum of Science and Nature in Bradenton, Florida, is the largest natural and cultural history museum on Florida’s Gulf Coast. Its mission is to inspire the joy of discovery and wonder for all ages through excellence in stewardship and engagement.

These illustrations were done for a physical and virtual exhibition.

So today I introduce you to a representative of one of the more modern types, Hyracodon nebrascensis (Hyrax-tooth from Nebraska). Can you guess what kind of mammal it was? No, not a horse. Actually, this was a rhino! So, Megacerops which I featured earlier, though looking more like a rhino, was closer to a horse, while Hyracodon, looking more like a horse, was closer to a rhino. Evolution is a funny business! So how, you may ask, is this possible? Well … the very, very first members of the whole order, the Perissodactyla (which today includes horses, tapirs and rhinos), all looked like tiny, slender, mini-horses. They had more toes than modern horses, though, three or four on each foot, had rounded backs, and were browsers and fruit-eaters skulking about the forest understory. The three modern branches, the rhinos, the tapirs, and the horses, started separating from each other about 50 million years ago, but for a long period evolved in parallel, all of them still looking very similar. But the brontotheres, the group including Megacerops, very early on started getting larger, until they were near-elephant-sized. When they went extinct, the rhinos took their turn and did the inflation thing. From forms like our little Hyracodon, giant forms evolved that by the early Oligocene were the biggest land mammals ever, the Paraceratheres. Here you see a couple of them roaming an Asian woodland, about 30 million years ago. They reached a shoulder height of 5 m/17' and a weight of about 15-20 tonnes. But, as you can see, they still looked a bit more like horses than rhinos.

Numerous other styles of rhinoceros also evolved. Another group that included early large members were the Amynodonts, which were like rhinos crossed with hippos crossed with tapirs, and were likely semi-aquatic swamp dwellers. True rhinos, which occurred in North America and Europe as well as Asia and Africa, at first were fairly small and light, and without horns. Some of the hornless forms evolved enormous tusks, similar to those of modern hippos. Horns developed soon and some early rhinos such as Diceratherium had a pair of short side-by-side horns on their snout. Others had the typical single horn on the nose or in some cases forehead. The arrangement found in modern African rhinos and the critically endangered Asian Sumatran rhino, with two horns, one in front of another, is a rather recent development, also found in the woolly rhino of the Ice Ages. True rhinos included light running types, long-bodied semi-aquatic types, and enormous, lumbering types that may still have been capable of fast running when pressed.

So back to our little Hyracodon. This was a light, early rhino-relative that lived in the woodlands and forests of North America from the late Eocene to the middle Oligocene, 32-26 million years ago. The region then had a much warmer climate and the forests included palms such as those of present-day Florida and broad-leaved trees some of which today are more typical of East Asia. Hyracodon had a lightly-built body, standing about 75 cm/2'6" at the shoulder with an overall length of 150 cm/5'. Like modern rhinos, it had three toes on each foot, each tipped by a small hoof. Its head was large for its body, and it had a broad snout. There was no trace of a horn. Its teeth were not yet high-crowned as those of modern rhinos, meaning it couldn't eat grasses or tough vegetation very well. Modern perissodactyls have a prominent gap between their front and cheek teeth; in Hyracodon, this was not yet well-developed. It would have browsed trees, shrubs and soft herbs, as could be found in the forest understory or in the lush vegetation on riverbanks and floodplains. It likely was a swift runner, necessary to escape the numerous predators of the period which I will soon also show you here.

Hyracodon was not on the main line of rhino evolution. Yet, it was a fruitful branch of the tree, with representatives living in North America, Asia and Europe. The hyracodont family culminated in the giant paraceratheres and then went extinct leaving no modern descendants. But their demise left the scene clear for the true rhinoceroses to evolve and diversify. Horses followed also, taking over the niche of fast-running plains and woodland dwellers. Early and even fairly modern horses for a long time included browsing types alongside the typical grazers. We shall be looking at some of those early horses next.

Willem

22.03.21 Front Page

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