When did it become extinct? The giant camel is thought to have become extinct around
1 million years ago. Where did it live? The giant camel lived in North America.
It is difficult to use the word camel without picturing the deserts of the Middle East and Asia; however, it may come as a surprise to learn that the camels originated and underwent most of their evolution in North America. The oldest ancestors of the camels are rabbit-sized, four-toed animals known from 40-million-year-old fossils. Over millennia, these ancestors gave rise to a number of species, of which only a few survive today. The giant camel was one of these species, and a very large one at that. The most familiar camel alive today, the dromedary (Camelus dromedarius), can be 2.1 m at the shoulder, 3 m long, and weigh 1,000 kg—a big animal, but it would look puny next to the giant camel, which, at 3.5 m tall and at least 1,800 kg, was the biggest camel that has ever lived.
Camels are very interesting animals that have evolved a number of adaptations for surviving in very tough environments, and the two species of camel alive today, the dromedary and the Bactrian (Camelus bactrianus), are born survivors, able to thrive in some of the harshest places on earth. What do we know about the giant camel? Was it similarly hardy? In some ways, it may have been, but the America in which it lived was very different to the land we know today. The climate was warmer and moister, so it is unlikely the giant camel was as hardy as the living species.
Camels are unique for their humps, which at one time were thought to store water, but are now known to store fat, making it possible for these animals to go for long periods of time without food. There is no way of knowing if the giant camel was humped. The vertebrae of its back do bear long spines, just like those of the modern camels, but this may have been for the attachment of the nuchal ligament that holds the head up. Camels also have a battery of adaptations that enable them to survive without water for several days at a time. They can lose up to 25 percent of their body weight in moisture before they get into difficulties. In contrast, most other mammals die if they lose only 3 to 4 percent. The camel limits the moisture it loses in its breath and produces viscous urine, both of which cut down on water loss. Dehydration in other mammals results in the blood getting progressively thicker, straining the heart until it can no longer beat effectively, but the camels get around this problem with red blood cells that are oval, rather than round, and it is thought that this enables the camel's blood to keep flowing even when the animal is dehydrated. When camels do find water, they really make up for their hardships, and they quench their thirst by drinking around 100 liters in one go, some of which is stored in special cavities in the lining of their large stomach.
It is unlikely that the giant camel was similarly equipped for survival. The America in which it lived, 1 to 5 million years ago, was a very different place to the continent we know today, and much of the land was forested, albeit sparsely in places. The giant camel probably never had to go without water for days at a time, but it needed the means of making the best use of the vegetation the open American forests provided. Its digestive system was undoubtedly very similar to that of the living camels, employing symbiotic bacteria to digest tough plant food. The giant camel, like its living relatives, could probably tolerate massive ranges in temperature that would cause most other mammals to keel over. Their thick fur can insulate them from the cold and the heat of the sun, enabling them to survive in temperatures as low as -40 degrees Celsius and as high as +40 degrees Celsius. The forested plains of Nebraska 1 to 5 million years ago were much warmer than today, but winter temperatures can be still be very low in the middle of a large continent, so the giant camel must have coped with cold winter conditions.
Although camels are champion survivors, they can be quite short-tempered beasts, and it seems the giant camel was no exception. Males of this extinct species sported well-developed canine teeth, and it is very likely that they used these to good effect during the breeding season, when disputes with other males over territory and females were commonplace.
The youngest remains of the giant camel are about 1 million years old, and we know that there were no humans in North America to hunt them at that time, so why did they become extinct? We don't know for sure, but climate change was the likely culprit. As the climate cooled, the preferred habitat of the giant camel—open forest—may have been replaced by grassland, and this enormous beast was squeezed out of existence.
♦ Today, the camels and their relatives are represented by the dromedary and Bactrian camels of the Old World and the llama (Lama glama), guanaco (Lama guanicoe), vicuña (Vicugna vicugna), and alpaca (Vicugna pacos) of the New World.
♦ Even though the camels, as a group, originated and underwent most of their evolution in North America, they died out there about 10,000 years ago, but millions of years ago, the ancestors of the two living camel species migrated into Asia via the Bering land bridge.
♦ The dromedary camel is actually extinct in the wild. It was domesticated at least 3,500 years ago (possibly as much as 6,000 years ago) and proved so useful to early civilizations that its populations exploded, and the wild animals were tamed or bred out of existence. The Bactrian camel still exists in the wild, but the population is no more than 1,000 animals, and they are limited to the northwestern corner of China and Mongolia, where they manage to survive in the unbelievably hostile Gobi Desert.
♦ The camels use a pacing gait to get around. The legs on the left side of the body step together, followed by the right legs. This unusual gait may look awkward, but it is actually a very energy-efficient way of getting around. A camel's pace can be quite unstable because of all the side-to-side motion; however, this is counteracted by its well-developed footpads.
Further Reading: Harrison, J. A. "Giant Camels from the Cenozoic of North America." Smithsonian Contributions to Paleobiology 57 (1985): 1-29; Breyer, J. "Titanotylopus (= Gigantocamelus) from the Great Plains Cenozoic." Journal of Paleontology 50 (1976): 783-88.
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