Named By: Bronn - 1831.
Synonyms: Rhinoceros tichorhinus, Coelodonta boiei.
Classification: Chordata, Mammalia, Perissodactyla, Rhinocerotidae.
Species: C. antiquitatis (type), C. nihowanensis, C. thibetana, C. tologoijensis.
Size: 2 meters tall at the shoulder, between 3 to 3.8 meters long. Some specimens may have been slightly larger.
Known locations: Across Eurasia (Europe, Russia, Asia).
Time period: Piacenzian of the Pliocene to early Holocene.
Fossil representation: Multiple specimens, including animals that have been completely preserved so that the full body and not just the bones is preserved.
is one of the most commonly represented ‘ice age’ mammals, yet
surprisingly it often only gets a name mention. Popularly known as
the woolly rhino, Coelodonta resembled the large rhinos that we know
today from Africa, but with a complete covering of fur over its
body. This was the main survival adaptation of Coelodonta which
inhabited most of Eurasia for over two and a half million years.
Coelodonta lived at a time that saw a series of glaciations across the Northern hemisphere that saw sheets of ice sweeping over much of the land, to receding back before covering the land again. This toing and froing of the ice sheets, combined with the colder climate that caused much of the lower soil depths to be permanently frozen, created vast expanses of frozen plains that were covered in grasses interspersed with low growing vegetation, and it is this ecosystem that Coelodonta seems to have been most adapted to. As with many similar herbivores, Coelodonta had sharp incising teeth at the front of the mouth and mashing molar teeth at the back. Between these two sets of teeth was a gap called the diastema, something else that is common amongst herbivorous mammals.
It’s uncertain exactly what kind of herbivore Coelodonta was. Some people think that Coelodonta was a grazer that cropped the grass plains like a cow, while others believe that it was a browser than fed from low growing plants. Either one is plausible; although most lean towards the grazing idea as grasses would have been much more abundant than more complex low growing plants. Coelodonta is thought to have used a fermentation method of processing the cellulose rich grasses in order to get the full nutritional benefit from the nutritionally poor vegetation of the ecosystem. This is actually a very clever method of digestion to adopt since as the grass is broken down by fermentation inside the gut of Coelodonta, it generates a small amount of heat that would have the added effect of warming the body from the inside.
This method of digestion seems to have been very efficient for Coelodonta as specimens where the main body is still preserved show that Coelodonta had a hump that rose up from its back above the shoulder blades. This hump was supported from within by the forwards dorsal vertebrae that had elongated neural spines growing from them, much larger the neural spines of the other vertebrae. This hump would have served as fat storage so that Coelodonta could build up fat reserves in the milder spring and summer so that it could better survive the colder winter when the plants had begun to die back, and possibly even had a deep covering of snow and ice.
Efficient processing of plants that have a low nutritional value is important for an animal like Coelodonta, but just as important for survival is efficient energy use and conservation. As a mammal, Coelodonta was certainly warm blooded, which means that the body works to try and maintain a stable temperature different from it environment (in this case much higher). Usually this is done by a process of involuntary muscle actions to generate heat such as the rapid and repeated constriction of muscle fibres, better known as ‘shivering’. In the short term shivering is not a problem, but prolonged shivering results in more calories being burned (used up), and the more that are burned the more likely that an animal will use up all it has. With no more calories to use, and not enough coming from the plants to maintain the level of use, an animal will stop shivering and quickly succumb to the cold, quite possibly dying from exposure.
As briefly mentioned above, Coelodonta had a covering of fur over its body, something which led to the name ‘woolly rhino’. This was the main line of defence against the cold, and would have trapped layers of air near to the skin. With these layers protected from mixing with the outer air they would be warmed by the body, and because this layer of inner air did not require any energy to maintain, it would have been like a blanket that slowed down the rate of heat loss from the body to the outside environment. A similar effect to this is simply wearing clothes as these layers of fabric trap pockets of air against your body to keep you warm. The effect is especially pronounced for thicker garments such as jumpers which offer a greater level of insulation. In addition to the fur, the body proportions of Coelodonta also helped to prevent heat loss. For example, the short legs of Coelodonta are a further adaption to the cold environment as they would reduce the surface area exposed to the cold climate, reducing the area for heat loss to take place.
No description of a rhino would be complete without mentioning the horn and this goes double for Coelodonta as it had two pronounced horns rising from its snout. The front horn at up to two meters long was the longer of the two, with the second horn rising from the middle of the snout being just over half to two thirds as big. The classical explanation for these horns is that they were what are termed sexually selected characteristics. This is based upon the knowledge that the horn would have been growing throughout the animals life, no more than a stump in a juvenile to fully developed in mature individuals. An older animal would have a more developed horn than younger individuals signalling to members of the opposite sex that it had the genetic makeup and success to make it to later life, and was more deserving of passing its genes down to the next generation than lesser individuals that had less developed horns. Such reasoning would explain the progression to larger horn sizes.
However there is a second theory regarding the front horn that is both an alternative and possible addition to the above theory. The front horn is strongly curved so that it extends out beyond the end of the snout. This horn is also laterally compressed so that when viewed from the front the horn looks more like a blade rather than a cone like in other genera. This leads to the popular interpretation the front horn was not just a display device but an actual tool that Coelodonta used to scrape snow off the ground as it moved its head from side to side. This would expose buried grasses that allowed Coelodonta to feed further without using energy to walk to an area that was uncovered, and would have been of particular use when Coelodonta was in areas that had frequent snowfall, but not a permanent covering.
The earliest remains of Coelodonta are from India and have been dated back to the end of the Pliocene period. The majority of other Coelodonta remains so far known are from Europe and Russia and these date back to the Calabrian of the Pleistocene, which suggests that Coelodonta first emerged in central Asia and then expanded its range. This expansion could have been synchronised to the availability of tundra-like environments that were constantly changed from the varying expansion and receding of the ice sheets that once covered the northern hemisphere.
One of the best examples of Coelodonta comes from a Tar Pit in Poland (near Starunia) that had its body frozen and preserved. Before this time the only visual representation of the living Coelodonta was in the form of cave art that had been made by ancient human beings.