Download EARTH HISTORY

THE GEOLOGIC RECORD
The principle of Uniformitarianism states that
processes observed on Earth today have
operated throughout history, and have produced
the rocks and fossils that we see.
FOSSILS
Fossils provide evidence about the ancient
history of Earth and the extinct biota (life).
Insects in Amber
Trilobite
Types of Fossils
Mold: a rock imprint of the shape of an organism
Cast: if a mold is filled with minerals, a cast is
formed.
Trace fossils: molds or casts (often of feet) that
can provide clues to behavior.
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LAW OF SUPERPOSITION
Fossils are in layers of rock. The oldest fossils
are in rocks that are further down. Younger
fossils are found in overlying rock layers.
Camel Evolution
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CHANGE IN ORGANISMS OVER TIME
Evolution is the change of organisms over time.
Natural Selection
Charles Darwin & Alfred Wallace believed that
organisms change over time by natural
selection.
NATURAL SELECTION
 There are differences in organisms that are
genetically determined.
 Organisms possessing traits that increase
survival will pass those traits on to their
offspring.
 They will live longer and have more offspring
 Their offspring will also have those traits.
 Adaptive traits (those that increase survival)
are “selected” by the environment.
Galapagos Finches
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COMMON ANCESTORY
Darwin believed
that the Galapagos
Finches had a
recent common
ancestor since they
had many traits in
common.
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DIVERGENT EVOLUTION When similar
populations become
more dissimilar, this is
called Divergent
Evolution.
Humans have sped
divergent evolution in
canines by the process
of Artificial Selection.
Adaptive Radiation:
similar organisms
adapt to differing
conditions (Galapagos
Finches)
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CONVERGENT EVOLUTION
Organisms that are not closely related but live
in similar niches can evolve similar traits.
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Coevolution: Two (or more) species change
together
EVIDENCE OF EVOLUTION
Homologous Structures have a common origin
but are adapted for each organism.
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Analogous Structures
have a similar function,
but not a common origin.
Vestigial Structures
have no use today
but were useful to
ancestors.
Examples:
Human tailbone and appendix
Blind cave fish
Pelvic bones of snakes and whales
Whale Skeleton at Pacific Science Center
Protein Similarities
The similarities of
amino acid sequences
indicate close
evolutionary
relationships.
Photos from Modern Biology, Holt, Rinehart & Winston. 2002 unless otherwise noted.