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 continue with the prehistoric beasties! Here I present to you three more related species from South America, called Pachyrukhines. Just like the previous three featured here, these are Notoungulates, hoofed mammals that very early, about during the early Palaeocene, or maybe even in the Cretaceous (when the non-avian dinosaurs were still around) had made it from North America to the continent of South America. I've been fascinated by the notoungulates ever since learning about them as a small child. These early hoofed mammals appear to have been related to the even-toed ungulates, or artiodactyls, as well as to the odd-toed ungulates, the perissodactyls - but perhaps more closely to the latter. Notoungulates were isolated when South America broke its connections with North America, and thereafter evolved in isolation, achieving great diversity. Early notoungulates were quite small, but soon some grew to large size. The toxodonts, especially, included some rhino-sized creatures.

But the other branch of the notoungulate order, the Typotheres, generally remained quite small. Many of them would have looked rather like rodents or rabbits. Our group of the day, the Pachyrukhines, belonged to the typotheres, and among them were some of the smallest, and very similar to rabbits. But they had somewhat different proportions, so I'm not sure if they also moved around preferentially by hopping, though they certainly would have been able to leap well if they needed to. They were also similar to the modern chevrotains or mouse deer .Their skulls were fairly large for their size. They had enlarged, forward-pointing incisors with a gap or 'diastema' before the cheek teeth, very similar to modern rodents, to which they're not at all closely related (as I said above, they're closer to horses, rhinos and tapirs). They appear to have had large ears and keen hearing. As always, my reconstructions liberally use my artistic imagination, as we only have fossilized bones, so the colour patterns and all features of the soft tissues are complete guesswork.

Our first species is Prosotherium garzoni. I base my reconstruction on a nice complete skeleton, but it is sometimes attributed to the similar species Propachyrucos. But they were so similar that I think my reconstruction could stand for either of them. Whatever the case, Prosotherium lived in the late Oligocene to early Miocene, 29-21 million years ago, as did Propachyrucos. They might have been ancestral to the next two species.

Next we have Pachyrukhos moyani, one of the best-known members of the group, giving the name to the subfamily Pachyrukhinae. Its large eyes indicate good vision as well, and it might even have been fully or partly nocturnal. This little animal lived in the early to mid-Miocene, 21 to 15.5 million years ago. Several species of Pachyrukhos have been distinguished.

Our final species is Paedotherium bonaerense, one of the most recent members of the Typotheria, and the Pachyrukhinae. These were quite small animals, averaging about 2 kg in weight. Their rodent-like front incisors might have been used for cropping grass and other low vegetation, but might also have helped them chew on hard items like nuts and seeds. This little animal lived very late, up to perhaps the early Pleistocene, a million years ago, but it was already present in the late Miocene, about 6.8 million years ago, meaning it was very successful. It lived in a variety of habitats, from open pampas-like to densely wooded.

We'll soon look at a couple more typotheres . . . and someday we'll return to the present again I hope!

Willem

29.01.24 Front Page

Back Issue Page