Camels of Yore
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 go back into the past yet again – but not so far this time. We're looking at camels! Today, they form a well-defined group. They belong to the Artiodactyla, the order of even-toed hoofed mammals. They are quite large, and differ from the other large artiodactyls in not possessing horns or other cranial adornments. They have padded, two-toed feet tipped by blunt nails or in early species proper hooves. The suborder they belong to, is called the Tylopoda or 'knob-feet'. The camel family also includes the llamas, Guanacos (wild llamas), the Alpaca, and the Vicuña. While these live in South America, and the remaining camels in Asia and Africa, in actuality the camel family was for most of its lifespan primarily characteristic of the Americas. In particular, several species of llamas as well as proper camels used to live in North America, until surprisingly recently. In fact, the llamas only reached South America quite recently, after the completion of the land bridge over Central America in the Pliocene (about 3 million years ago) allowed for a species interchange between the two continents. The ancient camels discussed in this entry all lived in North America. I'm discussing these for properly demonstrating the diversity of the group – in addition, several other prehistoric kinds are known.
The first camels, like almost all early hoofed mammals, were quite small. Protylopus petersoni (Peterson's before-knob-foot), with an overall length of about 80 cm/32", was as big as a typical dog (some sources quote it as being cat-sized or even rabbit-sized). I find very little information about this animal, and the only part of it I can find reference illustrations of, is the skull, so my reconstruction is otherwise conjectural. Protylopus lived in the late Eocene, about 40-45 million years ago. It was likely a forest dweller, and had four toes per foot rather than the two toes of later camels. Its teeth were not very thick or tough, meaning that it ate soft leaves rather than grass. It also had a complete dentition, everything from incisors through canines to cheek teeth, without gaps, while later camels lost some teeth and had/have extensive gaps in their dentition, especially at the fronts of their muzzles.
Poebrotherium wilsoni (Wilson's grass-eating beast) was quite a bit larger than Protylopus, reaching a shoulder height of 90 cm/3'. The genus lived in the Eocene and Oligocene, about 38-31 million years ago. Numerous fossils of this species have been found, first by a puzzled fur trapper called Samuel Culbertson in the badlands of Nebraska, whose family then sent it on to scientist Joseph Leidy. I think a note about naming is in order here. Animals, whether prehistoric or modern, are not necessarily named for the person who discovered them. They're named by the person (or persons) who publish the first named scientific description of them. They may be named for the discoverer or for someone else – but NOT for the person (or persons) naming them.
Poebrotherium likely lived in herds or flocks in country ranging from open plains to forests, feeding on grasses as well as the leaves of trees and shrubs. In turn it was eaten by, amongst other predators, the weird and huge pig-like animals, the Entelodonts, which will feature in an upcoming article.
Smaller than Poebrotherium but more advanced, was Stenomylus hitckcocki or 'Hitchcock's narrow molar tooth'. This one is also called the gazelle-camel. It was very slenderly built with proportionally long legs, and likely used speed to escape the many predators which lived with it in the Oligocene and Miocene period, around 30 million years ago. It stood about 60 cm/24" at the shoulder. It likely also lived in herds.
Much larger was Oxydactylus longipesor 'long-footed sharp-toe'. This long-legged, long-necked camel genus also lived from the Oligocene to the Miocene, from 31 to about 13.5 million years ago, a very successful spree of over 17 million years. It likely used its height to reach leaves up high in trees. An even longer-necked species was Aepycamelus, but I can't find any skeletal reference material of it online for a reconstruction.
Another strange form was the long-faced camel/llama Floridatragulus dolichanthereus ('long-fronted little goat from Florida'). This smallish species had an almost ridiculously long skull, to the extent that one wonders whether it might have been an anteater! But its dentition shows that it fed on plants, not ants. I have no idea why the long face, and I don't think anyone else knows either. It lived in the Miocene, from about 20.6 to 15.9 million years ago.
By the Pliocene/Pleistocene (the last two periods of the Cenozoic or age of recent life) we get camels of a very modern appearance. One such was Titanotylopus nebraskensis or 'titanic knob-foot from Nebraska'. Its name indicates that it was not merely a camel – it was a HUGE camel. It reached a bodyweight of about two tons, and a height to the top of its hump of over three metres. Yet, there was an even bigger camel around, called Megacamelus, which reached a height of 3.5 m and a weight of almost four tons. Again, I can't find skeletal reference material for it. But Titanotylopus lived from 10.3 million to 30 000 years ago and is well represented, with a couple of fine skeletons on display in North American museums. The type species was found, as you might guess, in Nebraska, and was widespread on the grassy plains, living through the ice ages and only dying out quite recently. Since it wasn't actually a desert-dweller, it might not have had all the specialized adaptations of modern camels, including a hump. But it might have had a hump indeed, since it had very long extensions of the vertebrae over its shoulders, which could have supported a fleshy or fatty hump, so I reconstruct it with one.
Another typical camel was Camelops hesternus, the 'western camel-face'. Slightly smaller than the titanic camel of Nebraska, it was still larger than most modern camels, with a shoulder height of 2.2 m and a weight of about 800 kg. It, too, survived throughout the Ice Ages. I reconstruct it here in the process of shedding its winter wool for a sleeker summer look. Again, it might have had a hump – or two, as I reconstruct it here. Camelops lived in much of western North America, likely on plains. It died out a mere 10 000 years ago (after surviving for over 3 million years). It was the last surviving North American true camel after the extinction of Titanotylopus and the High Artic Camel, Paracamelus. Since it survived so many climatic fluctuations prior to that point, there was likely a different factor that led to its demise. That factor might have been humans. There isn't much evidence of it having been hunted by early Native American people, but even small – but persistent – changes to its habitat and the animals that lived with it, could have had a negative effect on its population, and even a slow decrease could have, in several thousand years, have led to its extinction. But luckily, similar camels managed sometime in the Miocene or Pliocene, when low sea levels exposed a continuous bridge of land between America and Eastern Asia, to make the crossing. Today camels are rare in the wild, but quite abundant in domestication.
Finally, a North American llama, Hemiauchenia macrocephala (big-headed half-neck). This species, again, was larger than living llamas, reaching a weight of about 400 kg. In other respects, it was a quite typical llama, likely having soft, woolly fur to insulate it against both heat and cold. It first evolved in the Miocene, about 10 million years ago, and was very successful, yielding several species. In the Pleistocene, it moved over the Central American land bridge into South America, evolving into several more species. This or a related genus then evolved into the four living species (llama, guanaco, alpaca and vicuña) very recently. Of those four species, only two are wild, the other two being domesticated forms. But Hemiauchenia died out in North America about 11 000 years ago, like the native camels. Thus, the end of the Pleistocene saw camels disappear from their native country, to flourish only in lands they colonized recently.