Page 70 - The Restless Earth Fossils

Finding and excavating Fossils 6

exciting, and a rich learning experience, but the scientific value
of a fossil depends on the context of the rocks in which it is
found. The rock layers determine a fossil’s age and provide clues
to ancient environments. Other nearby fossils or microfossils
found within rock matrix reveal valuable information about
the entire ecology surrounding a fossil discovery. Extracting and
preserving fossils from rock matrix requires experience, skill, and
some training.

Finding Fossils

It is quite possible to stand on rich, fossil-bearing rock and not
see a thing. Paleontologists know this. When they venture into
new territory, the first thing they must do is develop a search
image for the kinds of fossils in that area. For example, William
Nothdurft, in his book The Lost Dinosaurs of Egypt, tells how
paleontologist Peter Dodson described the process to them when
they were hunting for dinosaur bone in Bahariya, Africa: “Lots of
people can walk across a piece of ground and step right on fossil
bone, never even see it. So when we get to a site like Bahariya, the
first thing we want to do is look closely at the bone that is char-
acteristic there. We look for the cell structure. If it looks fibrous,
you know it’s not a rock.” Fossil bones found in that area often
look dark like charred wood, sometimes with a purplish sheen.
All fossil bone shows the same porous structure of live bone up
close, but learning to spot the distinctive color and look of the
bone from a distance makes hunting a lot easier.
People hunting for fish fossils in Green River shale look for
the dark brown organic layers of mashed fish sandwiched between
the light tan layers of sandstone. A blow with a rock hammer and
chisel along the dark seam will often split the rock there, reveal-
ing a fish fossil. Hunting late in the day when the sun is low often
shows a slight bulge in a sheet of rock that marks the location
of a fossil. Many hunters start by circling around that bulge with
their normal tools, then slowly use special tools to work their
way through the overlying rock. Using this technique, they can
uncover nearly perfect specimens.

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