Yukon Beringia Interpretive Centre
University of Texas at Austin:
Denver Museum of Natural Science
Rancho La Brea Asphalt Deposits
Millions of years ago, the area of Los Angeles and Rancho La Brea lay beneath the surface of the
Pacific Ocean. During this time, marine sedimentary layers formed and in some places these
eventually became rich with fossil fuels produced from ancient sea life. When the ocean levels
receded some 100,000 years ago, the area of Rancho La Brea became land. New layers of
gravel, sand, and clay formed by the erosion of the emergent hills, and settled on top of the much
older marine sediments full of oil.
At Rancho La Brea, the crude oil has been seeping out of the ground through conduits and
fissures in the coastal plain sediments for the past 40,000 years, the seeps forming pools in low-
Bison antiquus graze with Western quaggas (Equus occidentalis) on a grassy flat in what is today
San Francisco Bay ca. 40,000 years BP.. Made famous by the La Brea Tar Pits in Los Angeles,
these extinct mammals roamed over wide areas of the West during the Pleistocene epoch, which
ended about 10,000 years ago.
Western Quaggas (Equus occidentalis), related to today's zebras apparently, graze with Bison
Harlan’s Ground Sloth
Harlan's ground sloth was
related to modern tree
sloths, but were much
larger, standing about 6
feet (1.8 meters) tall and
weighing 3,500 pounds
(1,600 kilograms). It had
very large, powerfully-
built limbs and claws.
Harlan’s ground sloth
moved in an unusual
manner, walking on the
backs of its forefeet and
the sides of its hind feet.
A scene in the low deserts of Imperial County, California of about 11,000 years ago,
showing a Shasta ground sloth (Nothrotheriops shastense), an animal perhaps resembling
something in between an anteater and a tree sloth. Plants include Agaves (Agave deserti),
Calico cactus (Echinocactus engelmanni), and Brittlebush (Encelia farinosa). This small
ground sloth was distributed over California, Nevada, Arizona, New Mexico, west Texas,
southern Utah, northern Mexico, and southern Alberta.
Western Camel (Camelops hesternus)
North American had native camels 10,000 years
ago. Today camels are native to Asia and
Africa. The extinct form probably looked
like a large dromedary, with longer limbs, toes
not as flattened, and perhaps a mid- dorsal hump.
Dire wolf (Canis dirus)
A pack of Dire wolves attacks a Western quagga (Equus occidentalis). This wolf had slightly shorter legs and a
broader snout and heavier jaws than the modern Gray wolf (C. lupus). It may have been adapted to dealing with
the larger prey fauna of the Pleistocene. The hyena niche may have been occupied by this species, as a hunter-
scavenger on large animals. In particular, it may have taken advantage of feeding on the remains of Saber-tooth
cat kills, as that predator could not ingest large bones with its long canine teeth. This large wolf has been made
famous by depictions of the La Brea tar pits, where hordes of Dire wolves scavenge dying animals trapped in the
University of Texas, Austin
Saber-toothed Cat (Smilodon
As its name indicates, the
saber-toothed cat had large
canines that were up to 7
inches (18 centimeters) long.
Saber-toothed cats were about
the size of modern African
lions, and had short, powerful
legs, indicating that they
probably hunted by
ambushing their prey rather
than chasing them down.
Remains of saber-toothed cats
have been found throughout
North and South America.
Denver Museum of
Nature & Science
A pencil sketch showing two Saber-tooths stalking a herd of Western quaggas (Equus
occidentalis) in a freshwater marsh with Tules (Scirpus sp.) in California's San Joaquin
Valley. A Llama (Hemiauchenia macrocephala) walks beyond the herd, and an Asphalt
stork (Ciconia maltha) is in the distance. In the water are White pelicans, Shovelers, Ruddy
duck, American avocets, and Western grebes. A Golden eagle soars overhead. A desert
tortoise (Gopherus agassizii) wanders off into the Saltbush flats (Atriplex polycarpa).
The short-faced bear was the largest carnivore in North America during the Ice Age. It was taller
than the brown (grizzly) bear, with longer, more slender hind legs, and a relatively short face
that was more reminiscent of a lion rather than any living North American bear. In North
America, the short-faced bear occupied the high grasslands west of the Mississippi, from Alaska
to Mexico. In these areas, it probably preyed upon bison, deer, and horses.
A herd of Columbian mammoths in a coastal California Redwood belt. These elephant-like beasts
were 10 to 11 feet tall at the shoulder. Bulls had massive sweeping tusks, possibly used to shovel
and scrape away brush or debris in feeding. Wear facets are deep and smooth the ivory, but are
difficult to interpret, as the tusks grow in a spiral manner. Males also may have fought using the
tusks-- in Nebraska, two fossil mammoth skulls were found locked together.
The Columbian Mammoth (Mammuthus columbi)
was the largest mammal to have been trapped in
the La Brea Tar Pits. Some individuals stood over
13 feet tall. The mammoth migrated into North
America from Asia about 2 million years ago.
The Columbian Mammoth was larger, but less
hairy, than the wooly mammoth which lived near
the ice sheets in the northern end of the continent.
The mammoth became extinct about 11,000 years
ago - about the same time the first humans
migrated into North America.
The tusks of the Columbian mammoth were up to
14 feet (4.25 meters) long, and its washboard-like
teeth were well-suited for chewing grass.
TIME - Late Pliocene to Late Pleistocene
RANGE - North America, south of the ice sheets.
DIET - Mostly grass but also leaves.
SIZE - 12ft (3.6 m) at the shoulders.
WEIGHT - 10,000 lbs (4,600 kg)
University of Texas, Austin
Mastodons were distant
relatives of mammoths and
elephants. In North America,
they were generally smaller
than mammoths, standing
about 7-8 feet tall at the
shoulder. Unlike the
washboard-like teeth of
mammoths, mastodons had
blunt, cone-shaped teeth that
were probably used to chew
leaves and pine needles in
Teratorns (Teratornis spp.)
Teratorns were related to condors, but were much larger usually. Three species
were found as fossil in the western United States, and the above form, Merriam's
teratorn (Teratornis merriami) was distributed in California, southern Nevada,
Arizona, and Florida. It had an incredible wingspan of 11 to 14 feet. The extant
California condor (Gymnogyps californianus) has a wingspan of 9 feet. These
giant vultures as a group went extinct at the end of the Pleistocene, possibly
from the reduction in large carcasses due to megafaunal extinctions. University
of Texas, Austin.
North of the ice sheet
WOOLY MAMMOTH mammuthus primigenius
This well known mammoth was a cold climate
dweller equipped with a thick layer of fat for
insulation, and an exterior of long black hair. It
was smaller than most mammoths, and had a
hump of fat behind its domed head. It fed on low
tundra vegetation in which it scraped away snow
and ice from with its ivory tusks. Several well
preserved remains have been found in Siberia
and Alaska and cave paintings in Spain and
France show depictions of the Wooly Mammoth
as seen by early humans. The mammuthus
primigenius went extinct only about 10,000
TIME - Late Pleistocene
RANGE - Europe / North America / Asia
DIET - Tundra vegetation
SIZE - 9ft. (2.7m) high
University of Texas, Austin
Enter man . . .
Mellars, NATURE, 432, 462-465
Late Pleistocene Modern • Neantherthal •
sites in France
Morwood, NATURE, 431, 1087
Lange, S. Dakota