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Renaissance scholars, argued that fossils were the remains of
organisms that had lived in the past.
By the early 1800s, the true nature of fossils was becoming
widely accepted. William “Strata” Smith, an English surveyor,
discovered at this time that sedimentary rock strata could be
identified by the fossils they contained. Smith grew up in a
region of England where fossils were particularly plentiful. He
became a collector, keeping careful notes on where he found
each fossil and in which type of sedimentary rock layers. During
his travels, he discovered that the succession of rock layers on
the south coast of England was the same as the succession of
rock layers on the east coast. Through his keen observations,
Smith found that each kind of sedimentary rock had a distinc-
tive group of fossils that was unlike the group of fossils in other
rock layers. Smith amazed his friends by telling them where and
in what type of rock they had found their fossils.
Today, the science of discovering fossils, studying the fos-
sil record, and deciphering the history of life from fossils is
known as paleontology. The word paleontology was invented
in 1838 by the British geologist Charles Lyell to describe this
newly established branch of geology. It is derived from clas-
sic Greek roots and means “study of ancient life,” and this
FIGURE 21.1 The Painted Desert, Arizona. This landscape has a requires a study of fossils.
story to tell, and each individual rock and even the colors mean something People sometimes blur the distinction between paleontol-
about the past.
ogy and archaeology. Archaeology is the study of past human life
and culture from material evidence of artifacts, such as graves,
buildings, tools, pottery, landfills, and so on (artifact literally
means “something made”). The artifacts studied in archaeology
can be of any age, from the garbage added to the city land-
fill yesterday to the pot shards of an ancient tribe that disap-
peared hundreds of years ago. The word fossil originally meant
“anything dug up” but today carries the meaning of any evidence
of ancient organisms in the history of life. Artifacts are, therefore,
not fossils, as you can see from the definitions.

TYPES OF FOSSILIZATION
Considering all the different things that can happen to the remains
of an organism and considering the conditions needed to form
a fossil, it seems amazing that any fossils are formed and then
found. Consider, for example, the animals you see killed beside
the road or the dead trees that fall over in a forest. Rarely do
they become fossils, because scavengers eat the remains of dead
animals and decay organisms break down the organic remains
of plants and animals. As a result, very little digestible organic
matter escapes destruction, but indigestible skeletal material,
such as shells, bones, and teeth, has a much better chance of not
being destroyed. Thus, a fossil is not likely to form unless there
FIGURE 21.2 The fossil record of the hard parts is beautifully is rapid burial of a recently deceased organism. The presence
preserved, along with a carbon film, showing a detailed outline of of hard parts, such as a shell or a skeleton, will also favor the
the fish and some of its internal structure. formation of a fossil if there is rapid burial.
There are three broad ways in which fossils are commonly
were well preserved and very similar to living organisms were
formed (Table 21.1):
finally accepted as remains of once-living organisms that
were buried in Noah’s flood. By the time of the Renaissance, 1. preservation or alteration of hard parts.
some people were starting to think of other fossils, too, as the 2. preservation of the shape.
remains of former life-forms. Leonardo da Vinci, like other 3. preservation of signs of activity.

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