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by Paul
Sereno
Made
of mud 90 million years ago, the
cast of a dinosaur footprint provides
many clues about the track maker.
Closing
the quarry
Our relentless pursuit of the
small theropod into the depths
of the hill will pay a big paleontological
dividend-many months from now.
It will become the best known
theropod from Inner Mongolia and
perhaps from the entire Gobi Desert.
We will know this animal from
head to toe. The skeletons and
clues from the exceptional bone
horizon will tell us about how
the animal moved, what it's social
life might have been like, what
it ate, and, perhaps, how it died.
Andy's
gloves tell of hard work in the
quarry.
Such information
is hard won and requires backbreaking
work and meticulous records. There
was no shortage of either at the
quarry, despite the help of a
bulldozer. We cleaned up the site,
leaving no stray wrapper or piece
of burlap. As we pulled out, we
gazed a little remorsefully at
the now familiar hills and mountains
of a quiet and beautiful place
in the Gobi, whose secrets from
the distant past will eventually
be told.
Prospecting
'til you drop
We poured over the geologic maps,
planning an aggressive week of
prospecting. After many days chipping
away at the same square meter
or two, we were really looking
forward to the long and strenuous
hikes that fossil prospecting
calls for.
There's art
and science to prospecting. The
artsy side is akin to having lopsided
luck. You just happened to be
in the right spot at the right
time. You slipped on a rock that
dislodged another, which exposed
a fossil.
Jeff
uses his eyepiece to have a closer
look.
But you'd
be surprised how much of fossil
discovery isn't plain serendipity.
Some find more of their share
of discoveries. Some always find
the small fossils. Others find
the best ones. Some teams do much
better than others in the same
general field area. This side
of prospecting is called having
the "nose."
Andy, on his
first dinosaur expedition, has
developed a keen awareness for
fossils. "The most important thing
is to learn the color and textures
of the fossils in the search area.
Then you can really key in." He
added quickly, "Also, you gotta
be willing to get down close to
the rock, to stop and check, all
of the time."
"For a team,
I think it's legs that are most
important," suggested Paul. "We
often need to cover an immense
area. Some of our best fossils
are well exposed, but you got
to be able to find them. You need
a great pair of legs, because
an hour of prospecting time can
involve miles of walking over
rough terrain."
Dinosaurs
large and small
The prospecting yielded results
on our first day. A new predator,
a dromaeosaur, was hunted down
by our microfossil specialist,
Fabrice. His background - years
of searching for shark's teeth
- has given him a keen eye for
small fossils.
"I found these
small vertebrae just over there
and the rest of the bones nearby,"
remarked Fabrice, pointing to
a very ordinary slope on the side
of a very ordinary hill. "They
are so tiny," exclaimed Mike.
"This is the tip of a small claw,"
remarked Jeff, pointing to a small
triangular fragment dwarfed by
the palm of his hand.
Two
characteristic vertebrae from
a strongly inclined neck record
the presence of a new small raptor.
We decided
to double back to the hill with
sieves the next day, as the pile
of tiny hand-picked bones from
the site included many from an
unknown small predator -- a dromaeosaur
or relative of Velociraptor.
Dave
sorts through the seives catch,
plucking fossil pieces that otherwise
would have gone unnoticed.
More vertebrae
and other bones appeared in the
sieves, as we went through the
sediment on the side of the hill
with a fine-tooth comb. The most
amazing piece was the base of
a small claw, to which we reattached
the tiny claw tip, found the day
before.
The sickle-shaped
claw was from the hand of a very
small dromaeosaur. "This was a
vicious predator, perhaps only
three or four feet long as an
adult," remarked Paul.
Small
enough to balance on a fingertip,
the tiny hand claw of a raptor
was found by the sharp-eyed team.
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