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 remain with the prehistoric animals I reconstructed 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 on animals found in their Nebraska Diggings of about 35-30 million years ago, around the changeover from the Eocene to the Oligocene Periods. The time was one of transition: global climates became drier, forests gave way to grasslands, and ancient groups of mammal gave way to more modern lines.
Here is a big panorama I painted for the exhibition, showing a herd of Merycoidodon culbertsoni ('Culbertson's Ruminating Tooth) with a single Megacerops strolling past in the background. The time is the Late Eocene, about 35 million years ago; the place, what is now Nebraska. The climate was much more similar to that of Southern Florida today, with palms and other warm-climate trees, extensive rivers and floodplains. From the end of the Eocene to the beginning of the Oligocene there was a climate change event affecting much of the world. Over North America, there was a general transition from a moist, warm climate to a drier, cooler one. Moist forests and tree-rich savannahs were replaced by extensive dry, open grasslands. Many mammals couldn't cope with this change; the grasses were tough to chew and digest and the kinds of nutrients available in the grasslands may not have been very compatible with their overall metabolisms and systems. The Megacerops you see here would have been the last of its line; the entire group died out in the early Oligocene. But the merycoidodon herd you see here represents a species that did successfully weather the changing, er, weather. The genus Merycoidodon survived into the early Miocene, about 16 million years ago.
Merycoidodon is often known as Oreodon, or 'Hill Tooth' because its teeth were often found in hilly terrain such as the badlands of South Dakota. The group it belonged to also are known now as the Oreodonts. It was a big and diverse group that flourished in large numbers for a period of over 30 million years. Oreodonts were entirely restricted to North America. They varied from small rabbit-sized creatures to ones as large as a cow or a large pig. Some lived in forests, some in deserts, some thrived on the new grassy plains, and some might have been semi-aquatic like hippos.
Of the oreodonts, Merycoidodon is the one whose fossils are found in the largest numbers today, from Florida to Alberta in Canada. They must have been very successful in their time. They look strange, though, and there's no modern-day mammal quite like them. They resemble pigs a bit, and also sheep, but they might have been more closely related to camels. The jury's still out on their closest living relatives, but it's agreed that they were artiodactyls, or even-toed hoofed mammals. Merycoidodon culbertsoni was close to a sheep in size, with a body about 1.4 m/4'4'6" long standing about 60 cm/24" at the shoulder. It had a rather box-shaped skull, and a complete dentition without prominent gaps in its tooth row except for a small space between its canines and first premolars. Its long, sharp canine teeth were likely used in defense or when males vied for females. It had no other way to defend itself. In front of each eye, there was a hollow in the skull suggesting that it had a facial scent gland, such as is found in some deer and antelope species. This might have been used for marking each territory and for general scent communication in the herd. On each foot it had four functional toes (and an additional small inner toe on the front foot that didn't touch the ground) ending in small, nail-like hoofs. It had a long tail.
In lifestyle, merycoidodons probably resembled small deer-like browsing mammals, except for living in herds, which is today more a lifestyle of large, grazing mammals like zebras and wildebeests. While their teeth suggest a diet of soft leafy browse as is found in the understories of forest and woodlands, they might have grazed on juicy riverside grasses as well, and might have used their sharp front teeth and canines to strip bark from trees. With their short legs, they likely could not run very fast. They were likely preyed upon by the cat-like early carnivores that inhabited the forests of those days, which I will feature in this column soon. It is unclear why Merycoidodon died out, which it did about 16 million years ago, but it seems to have given origin to a number of descendant oreodont lineages that persisted after it, the latest oreodonts vanishing from the Earth in the late Miocene, about 7 million years ago.