Geoscience Reference
In-Depth Information
288
288 Observation Pit at
Rancho La Brea, Hancock
Park, Los Angeles, showing
concentration of bones in tar
deposits.
Human remains
The skull and partial skeleton of a human
female have been recovered and carbon-
14 dated at 9,000 years BP, thus
postdating the bulk of the biota. 'La Brea
Woman' was between 20 and 25 years
of age (Kennedy, 1989) and stood
approximately 1.5 m (5 ft) tall. The
fractured skull suggests that she may have
been murdered and her body dumped in
a shallow tar pool (Bromage and
Shermis, 1981), although an alternative
hypothesis suggests a ritual burial
(Reynolds, 1985). Many human artefacts
have also been found, mostly less than
10,000 years BP, and include shell
jewellery,
sheer numbers of bones preserved ( 288 )
define it as a Concentration Lagerstätte;
more than 50 wolf skulls and 30 sabre-
toothed cat skulls have been collected
within just 4 cubic metres (140 cubic ft).
Bones and teeth are preserved almost in
their original state, apart from their
penetration by oil, which gives a brown or
black colouration. Up to 80% of the
original collagen is retained (Ho, 1965)
and microstructure is well preserved
(Doberenz and Wyckoff, 1967). Surface
markings on bones still show the positions
of nerves and blood vessels and the
attachment points of tendons and
ligaments. Often oil has accumulated in
skull cavities preserving, for example, the
tiny bones of the middle ear or even the
remains of small mammals, birds, and
insects. Curiously, epidermal structures are
rarely preserved; occasional hairs and
feathers are known, but nails and claws of
mammals or talons and beaks of birds are
not. Chitinous bodies of insects retaining
the iridescent colours of wing cases, and
fleshy leaves and pine cones, thoroughly
impregnated with oil, are not uncommon.
bone
artefacts,
wooden
hairpins, and spear tips.
Dire wolf and other dogs
The dire wolf ( Canis dirus ) is the most
common mammal from La Brea, known
from over 1,600 individuals ( 289, 290 ).
They probably fed in packs on animals
stuck in the tar and became trapped
themselves. The large head with
strong jaws and massive teeth made it the
major predator of La Brea. Other dogs
include the grey wolf ( Canis lupus ) and
coyote ( Canis latrans ), the third most
common La
D ESCRIPTION OF THE R ANCHO L A
B REA BIOTA
The fauna and flora from Rancho La Brea
is well documented and illustrated by
Harris and Jefferson (1985) and Stock and
Harris (1992).
Brea mammal, which is
slightly
larger
than
the
modern
representatives of
this
species ( 291 ).
Domestic dogs
are
also
present, one
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