L3 Vocabulary: Fossil & Fossil Record
Fossil
The remains or
imprints of
organisms that
once lived
Fossil Record
All of the fossils
that have been
discovered
Essential Question
What evidence
supports the
theory of
evolution?
KEY TOPICS:
1.
Fossil Evidence
2.
Structural Evidence
3.
Genetic Evidence
4.
Embryological Evidence
Fossil Evidence
•Fossils are the remains or traces of once-living
organisms
•Cast fossils form when an organism is covered by
sediment; as time passes, more sediment is layered
over the organism. Over time, minerals seep into
the organism and replace the organism with stone.
•The fossil record is the history of life in the geologic
past as preserved in fossil; older fossils are in lower
rock layers.
Structural Evidence
•A common ancestor is the most recent species from
which two different species evolved.
•An unused body structure in an organism is a structure
now reduced in size or function that may have been
complete and functional in the organism’s ancestors.
•Shared body structures suggest that organisms had a
common ancestor.
Genetic Evidence
•The more similar the DNA is between two species,
the more closely related the species are likely to be.
Embryological Evidence
•If organisms share patterns of development, it is
likely that they also share a common ancestor.
Lesson 4 Vocabulary
Extinction
When every
individual of a
species dies
Geologic Time Scale
The standard method
used to divide Earth’s
long 4.6-billion-year
history into
manageable parts
Essential Question
How has life on
Earth changed
over time?
KEY TOPICS:
1.
Fossil Record
2.
Geologic Time Scale
3.
The Precambrian and the
Paleozoic
4.
The Mesozoic and
Cenozoic Eras
Fossil Record
•Fossils of bacteria place the origin of life on Earth at
about 3.8 billion years ago.
•Fossils are dated by relative dating, which
determines age by comparing two fossils, and
absolute dating, which estimates the time at which
a fossil formed.
•The presence of a species and the number of fossils
in the fossil record give clues to extinctions and
mass extinctions.
Geologic Time Scale
•The geologic time scale divides Earth’s history into
manageable parts. The largest division is the eon.
Eons are divided into eras. Eras are further divided
into periods.
•The four major divisions of the geologic time scale
are Precambrian time, the Paleozoic era, the
Mesozoic era, and the Cenozoic era.
•The major divisions in the geologic time scale
correspond to mass extinctions.
The Precambrian and the Paleozoic
•Single-celled, ocean-dwelling organisms dominated
the Precambrian.
•Prokaryotes capable of photosynthesis evolved and
increased the amount of oxygen on Earth. This
allowed for the evolution of new species that need
oxygen to live.
•During the Paleozoic, living things colonized the
land. Insects and vertebrates evolved.
The Mesozoic and Cenozoic Eras
•During the Mesozoic, dinosaurs evolved and the
mammals and birds appeared.
•The Cenozoic era is the current era. During this era,
primates, including humans evolved.