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Geologic Timeline: The last 144 million years of Earth's 4.6 billion year history.
Pleistocene camels.

FOSSIL FIELD GUIDE

Camelops hesternus
Western Camel
Family: Camelidae

Time
Pleistocene Epoch


Place
Central and western North America

In Our Region
Carlsbad, National City, Anza-Borrego Desert, Rancho La Brea


Western camel jaw
SDSNH catalog no. 75052

Description
This extinct camel looked much like the modern Bactrian and dromedary camel of Asia and Africa. Camelops stood about 7 feet (2.2 meters) tall at the shoulder. As members of the camelid family, these animals had very unusual feet, with four toes reduced to only two elongated digits. Splaying of the toes and a broad foot pad were probably adaptations that helped when walking on rough terrain or soft sand. Their leg bones were also very elongated and adapted for walking long distances when searching for food and water.

The shoulder joint of the Western Camel was much higher than the hip joint, with a rather steep slope in the hindquarters down to the tail, similar to what we see in modern camels. From studying the tall neural spines on its upper back vertebrae, scientists believe that the single hump must have looked similar to that of a dromedary, although it was placed a bit farther forward.

Despite the fact that we presently associate camels with the deserts of Asia and Africa, the camelid family evolved in North America during the middle Eocene, at least 44 mya. By the Oligocene, 28 mya, a small delicate camel, Miotylopus, occupied open habitats in southern California, hunted by nimravid 'cats' and early canids. By 3 mya, an extraordinary tall camel, Titanotylopus, lived in coastal areas of southern California and probably fed on coarse shrubs.

During the Pleistocene, great numbers of Camelops probably moved in herds across North America, but they became extinct on this continent about 11,000 years ago. Camelids survive today in the New World as the llamas, vicunas, alpacas, and guanacos of South America. In the Old World we still have the modern-day camels of Africa and Asia.

Ecology
Studies of the Rancho la Brea Camelops hesternus fossils reveal that rather than being limited to grazing, this species likely ate mixed species of plants, including coarse shrubs growing in coastal southern California. Paleontologists think that Camelops was actually more closely related to llamas than to living camels.

Camelops probably could travel long distances, similar to the living camel. We do not know if it had the ability to exist for long periods without water that modern-day camels display; this may be an adaptation that occurred much later, after camelids migrated to Asia and Africa.

Camelids evolved an unusual style of walking called "pacing," which means that the front and back legs on each side of the body move forward together. We can see fossil evidence that this pacing movement occurred with the earliest camels, since there are fossil trackways that document it.

Further Research
Why did the camelid family become extinct in North America? In southern California alone, there were at various times at least eight different forms of camelids, yet by 11,000 years ago, the entire family was extinct on this continent.

Suggested Reading
Jefferson, George T. and Lowell Lindsay. 2006. Fossil Treasures of the Anza-Borrego Desert. San Diego: Sunbelt Publications.



Text: Margaret Dykens and Lynett Gillette
Illustration: William Stout


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Pleistocene Epoch 1.8 million-10,000 years ago.
Pliocene Epoch 5-1.8 million years ago.
Miocene Epoch 24-5 million years ago.
Oligocene Epoch 34-24 million years ago.
Eocene Epoch 53-34 million years ago.
Paleocene Epoch 65-55 million years ago.
Cretaceous/Tertiary Boundary Rock, 65 million years ago.
Cretaceous Period 144-65 million years ago.
Earth's history began 4.6 billion years ago.
MYA = million years ago.