Page 105 - Science Course 3 (Book 1)
P. 105
Mo3-L1a: How are Fossils Formed?
Based on fossil evidence, scientists can recreate the physical appearance of species that are no longer alive
on Earth.
Fossil Formation
After an animal dies, any soft parts animals do not
eat break down.
A cast is a fossil The impression of an
copy of an organism organism in a rock is
in a rock. called a mold.
A trace fossil is the
preserved evidence
of the activity of an
organism.
Only the dead animal’s hard parts, such as bones,
shells, and teeth, remain. In rare cases, the
original tissues of
Under rare conditions, these parts become fossils. an organism can
be preserved.
How Fossil Form Key Concept
How are fossils formed?
Mineralization Carbonization
List the different ways fossils can form.
Rock-forming minerals Fossil films made by
in water filled in the carbonization are
small spaces in the usually black or dark
tissue of these pieces brown. Fish, insects, and
of petrified wood, Water plant leaves, such as
also replaced some of a fern frond, are often
the wood’s tissue. preserved as carbon
Mineralization can films.
preserve the internal
structures of an
organism.
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