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Ice
Age Yukon and Alaskan Camels
It is a poorly known fact that camels (Family Camelidae)
originated and underwent most of their evolution in North America. The earliest known Late
Eocene (about 40 million years ago) camelids like Protylopus were rabbit-sized with
four-toed feet and low-crowned teeth. The sheep-sized Poebrotherium of Oligocene
time (37 to 24 million years ago) was common in open woodlands of what now is South
Dakota, and had already "lost" the lateral toes. During the Miocene (24 to 5
million years ago), camels increased in size with lengthening necks and limbs, also
developing and efficient pacing gait for traversing the expanding steppe and grassland
habitat of the time. In the Early Pliocene some 5 million years ago, camels spread,
eventually reaching South America and the Old World(via a Bering Isthmus). Some of these
camels were gigantic, like Titanotylopus from Nebraska. The South American lineage
gave rise to such species as llamas and their relatives all adapted to grazing on
high-altitude steppes.
Ironically, camels became extinct in their place of origin
toward the close of the last glaciation. Although we know a good deal about camels and
their origins, few people realize that they once lived in the Yukon and Alaska.
Camelid bones recovered in the Old Crow River Basin in
northern Yukon are chiefly from large camels, much larger than either the modern
twin-humped camel (Camelus bactrianus, which occurs naturally in small numbers in
the Gobi Desert of central Asia) or the single-humped dromedary (Camelus dromedarius,
used domestically from North Africa to India and now running wild in the Australian
outback after introduction there). The fossils are closest in shape and size to a very
large member of the true camel group (Camelini) like Titanotylopus mentioned
earlier. That camel had long, massive limbs, a relatively small braincase, a convex region
between between the eye sockets and well-developed third premolar teeth in both jaws. It
was about 3.5 m tall, with long spines on the thoracic vertebrae indicting a large hump.
Its snout was shorter than that of Camelops, the other smaller camel reported from
Yukon and Alaskan Ice Age deposits. Evidently males were larger and had more robust skulls
and canine teeth than females. Titanotylopus occupied western North America from
about 5 to 1 million years ago. Could these Yukon Titanotylopus-like camels be
relics of an earlier migration to Eurasia, having given rise to Giganotylopus
(considered by some experts as identical to Titanotylopus) of the southern
Ukraine(Odessa and Cherkassy) about 5 million years ago?
A number of bones of another smaller camel (Camelops
hesternus, the western camel, distantly related to the modern llamas of South America)
have been recovered on the banks of the Sixtymile River near the Yukon-Alaska border.
Oddly, all Camelops bones are from the same locality, a placer-mining site of Chuck
and Lynn McDougall. In the process of washing away masses of frozen silt("muck")
covering the gold-bearing gravels, the miners sometimes encounter bones of Ice Age
animals. This particular site has produced hundreds of fossils belonging to woolly
mammoth, steppe bison, large and small horses, American mastodon, caribou, mountain sheep,
helmeted and tundra muskoxen, caribou, moose, wapiti, wolf, wolverine, scimitar cat,
American lion, ground squirrel (with ancient nests and droppings), bird and a virtually
perfect carcass of a black-footed feret, fur and all! One of the Camelops bones
from Sixtymile was radiocarbon dated to about 23,000 years ago, near the cold peak of the
last glaciation. Climate was drier then, and cool steppe-like conditions with broad grassy
tracts prevailed compared to the spruce forest that covers the area now, with tundra on
the uplands.
Thirty-six western camel remains have been reported from
mining sites near Fairbanks, Alaska (about two-thirds are from Cripple Creek and Gold
Hill; others are from Engineer, Fairbanks and Ester creeks). Dates on a number of the
bones range between 40,000 and 25,000 years ago when climate began cooling toward the peak
of the last glaciation. So, perhaps western camels did not enter Yukon and Alaska from the
south until the relatively warm mid-Wisconsinan interstadial(about 50,000 to 25,000 years
ago), dying out there toward the peak of the last glaciation.
Western camels were confined to North America, having been
most abundant in the western United States, southwestern Canada(Alberta and Saskatchewan)
and central Mexico during the last part of the Ice Age(about 600,000 to 10,000 years ago).
They probably reached unglaciated Yukon and Alaska by migrating northward via dry terrain
on the eastern flanks of the Rocky Mountains during a relativley warm period. How did they
survive the northern winters? Modern camels are able to grow thick pelts under cold
conditions. I have seen Bactrian camels at ease, wandering over snow-covered land in
mid-winter at a game farm in Alberta, and travellers have encountered them "plodding
stolidly through north-Asiatic blizzards".
In life, the western camel probably looked like a large
dromedary, however its limbs were about a fifth longer, its head was longer and narrower
and the face was flexed downward to a greater extent. The shape of the snout(premaxilla)
indicates that Camelops probably ate as much leaves, forbs(herbs other than grass)
and fruits, as grass. The long neck and limbs allow it to reach high browse as well. Camelops
seems to have been adapted to arid scrublands and grasslands, and Yukon and Alaskan finds
suggest that it could tolerate cool, at times snow-covered steppe-like grasslands.
Western camel remains have been reported from at least 18
Paleo-Indian sites dating between about 12,600 and 10,000 years ago(when the species seems
to have become extinct). A camel bone chopping tool was found at the Colby site, and there
is evidence of butchering at the Casper and Carter/Kerr-McGee sites, also in Wyoming.
C.R. Harington, Canadian Museum of Nature
June, 1997
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