| Why are the fossil skeletons on
display in the Page Museum brown in color? |
| The brown color results from the saturation
of asphalt into bones over a period of thousands of years. |
| Are the skeletons made of real
bones? |
| Nearly all of the skeletons on display
are real fossil bones found at the tar pits. They have been mounted
using an internal steel and wire armature . Missing bones or parts
originally composed of cartilage have been reconstructed with resin
or plaster. Only the Shasta ground sloth is 100% plaster because the
bones of this species are rare from Rancho La Brea. In addition, the
Columbian mammoth and American mastodon tusks are fiberglass, since
the original tusks were dentine rather than enamel and consequently
decayed in the asphalt. |
| How old is the oldest fossil from
Rancho La Brea? |
| A wood fragment was dated at around
40, 000 years old using the Carbon-14 radiometric dating method. |
| When did the extinct animals found
here live in this region? |
| Extinct mammals, like the saber-toothed
cats and mammoths, and birds, like Merriam's Teratorn and Grinnell's
Eagle, roamed the Los Angeles Basin for several hundred thousand years.
These and other extinct species were entrapped and their remains were
preserved between 40,000 and 10,000 years ago at Rancho La Brea, during
the last of four great Ice Ages at the end of the Pleistocene Epoch. |
| How many fossils have been removed
from Rancho La Brea? |
| Since 1906, more than one million
bones have been recovered representing over 231 species of vertebrates.
In addition, 159 kinds of plants and 234 kinds of invertebrates have
been identified. It is estimated that the collections at the Page
Museum contain about three million items. |
| What are the most commonly found
animal remains? |
| Dire wolves are the most common large
mammals from Rancho La Brea, with several thousand individuals represented
in the Page museum collections. The remains of over 2,000 individuals
of saber-toothed cat rank second. |
| Why are so many fossils found in
a single asphalt deposit? |
| Large deposits of fossils and asphaltic
sand formed in the same location by cyclic build-up over thousands
of years. The asphalt was sticky enough to entrap a variety of Ice
Age animals, both large and small, and is an excellent preservative
for plant and animal remains. |
| How did the animals become entrapped? |
| Asphalt is very sticky, particularly
when it is warm. The warm temperatures from late spring to early fall
would have provided the optimum conditions for entrapment in asphalt.
Small mammals, birds and insects inadvertently coming into contact
with it would be immobilized as if they were trapped by flypaper.
The feet and legs of heavier animals might sink two or three inches
below its surface. Depending on the time of day or year, strong and
healthy animals may have managed to escape, but others would have
been held fast until they died of exhaustion, or fell prey to passing
predators. Under the right conditions, a single mired large herbivore
would attract the attention of a dozen or more hungry carnivorous
birds and mammals, some of which would find themselves trapped, providing
more food for other carnivores. This cycle repeated during the 30,000
years that fossils were accumulating at Rancho La Brea. It is estimated
that one entrapment episode involving ten large mammals every decade
would furnish more than enough fossil remains to account for all the
large mammal and bird fossils collected since the turn of the 20th
century (over 1 million!). |
| Is entrapment still occurring at
Rancho La Brea? |
| Yes. About 8 -12 gallons (32 - 48
liters) a day ooze and bubble to the surface occasionally trapping
invertebrates (insects and worms), reptiles (lizards), birds (mostly
pigeons, but also hawks, egrets, ducks, doves, and sparrows), small
mammals (rodents and rabbits) and occasionally large mammals (dogs
and humans) especially during warm days when the asphalt is softest. |
| What was the Ice Age like in the
Los Angeles Basin? |
| Evidence indicates that four plant
associations occurred in the region. Coastal sage scrub broken with
groves of pines and cypress grew in the immediate vicinity of the
asphalt seeps. Chaparral, with some pine and juniper scattered within,
covered the slopes of the local mountains. In deep mountain canyons
there were redwoods and other plants that mixed up slope with coast
live oak and with a riparian (stream side) association in the canyon
bottoms. Stream courses crossing the plain supported a riparian association
that included sycamore, walnut and numerous herbs. Most of the types
of plants that live here today were present here in the late Pleistocene.
This indicates that rainfall was strongly seasonal, with most precipitation
occurring in the late fall, winter and early spring, whereas the summer
months were relatively dry. Many plant species found in these fossil
deposits now only live along the summer fog belt from San Luis Obispo
to Oregon and on the Channel Islands. A few species occur today in
the southern Sierra Nevada Mountains between 4,000 and 6,000 feet
elevation. This suggests that the late Pleistocene maritime climate
at Rancho La Brea was cooler, more moist and equable than it is today. |
| Are any of the fossils available
for sale? |
| The Page Museum does not sell original
fossil material. However, reproductions in fiberglass resin of selected
items from the Rancho La Brea collections are available for purchase
through the Page Museum Gift Shop. A more extensive selection is available
to other museums and universities through the Collection Manager of
the Page Museum. |
| What were the climate and vegetation
at La Brea like when the extinct animals were alive? |
| While under the influence of the waning
Ice Age, La Brea's climate was somewhat cooler and moister than today.
This climate produced a vegetation similar in type to that which presently
exists on California's Monterey Peninsula, located approximately 300
miles to the north. Fossils evidence also indicates shallow ponds
and marshes existed at La Brea. Intermittent streams transported drier
inland vegetation as well as traces of redwood, which probably grew
in sheltered canyons in the local mountains. |
| What was the frequency of entrapment
at La Brea? |
| The 10,000 individuals mentioned in
answer 14 became trapped during about 30,000 years of time (roughly
40,000 to 10,000 years ago). On the average this represents 10 animals
caught every 30 years. |
