The early excavations of La Brea simply involved the removal
of bones and the identification of the species present. Since 1969, research
has been more precise and sophisticated. Although few new species are expected
to be recovered, advances in various techniques mean that there is still
a great deal of information to be gained from La Brea.
Climatic Information
Fossil plants from La Brea can be particularly informative
when determining the climatic conditions at the time of deposition. Many
of the fossil plants belong to extant species, so the climate
in which these species now live is likely to be similar to that at La Brea
in the past.
Ecosystems
As the fossil
diversity of the La Brea tar pits is so
high, it gives a good representation of the ecosystem present in California
between 40,000 and 8,000 years ago. However, the fossils give limited information regarding the relative abundance of species, because there is an apparent
taphonomic bias towards predator and scavenger species.
The diet of some of the La Brean herbivores can be determined directly from the preservation of pockets of plant material trapped on their teeth. A high proportion of dicotyledons on the teeth of bison, camels and horses supports the pollen and seed evidence suggesting that grasses were probably quite rare at Rancho La Brea.
Geology and Taphonomy
More accurate taphonomic data has
allowed a better understanding of the way in which organisms were trapped
and preserved.
Functional Morphology
Although the soft tissue of the La Brea vertebrates is
rarely preserved, their hard parts are preserved in detail. Surface features
and internal structures such as nasal turbinals and auditory ossicles allow
a detailed study of the functional morphology of various species. For example,
the hyoid apparatus preserved in some Smilodon specimens indicated
that these creatures could purr and roar.
Population Studies
The large number of bones collected means that there
are numerous examples of each element to make comparisons with, allowing
biometric, ontogenetic and ageing studies to be carried out. For example,
an analysis of the dentition of Bison antiquus revealed that juvenile
individuals trapped in the tar pits were aged betwee, 2-4 months,
14-16 months or 26-30 months. This indicates that bison were annual migrant
visitors to La Brea, since each age group of juveniles is separated by
a year.
Pathology
Around 8,000 of the La Brea specimens show signs of pathology.
These may provide information on a variety of subjects. For example, evidence
for intraspecific combat in Smilodon has come from the damage observed
in their bones. Since the sample size of La Brea is so large, pathology
can be used to assess the health of a population. In a recent study by
Duckler and Van Valkenburgh, the percentage of pathological specimens in
populations of dire wolf, coyote, sabretooth, bison and camel were investigated.
When compared to modern healthy and stressed populations, the results indicated
that these species did not appear unhealthy in the lead up to their extinctions
(except coyote, which is still extant). Information such as this may be
important in determining the causes of extinction of these species.
Anthropology
As well as the use of asphalt by Indians
centuries ago, La Brea has other links to anthropology. La Brea Woman was
a human fossil excavated from the tar pits. She was thought to have dies
around 9,000 years ago, at the age of 22-24 years old. Her skull was crushed,
suggesting that she had been murdered.
Education
As well as the broad scientific value of La Brea, the
tar pits are organised to promote education. The visitor observation centre
in Hancock Park allows the public to watch the current excavations from
Pit 91, from which arounf 1000 bones a year are recovered. The collections
in nearby museums allow a further appreciation of the palaeontological
richness of La Brea.