The%20Fossil%20Record

1
The Fossil Record
Chapter 17.1
2

• The fossil record provides evidence about the
  history of life on Earth. It also shows how
  different groups of organisms, including species,
  have changed over time.

3
How Fossils Form

• The formation of any fossil depends on a precise
  combination of conditions.
• Most fossils form in sedimentary rock. (test
  question)
• sedimentary rock
• The weight of layers of sediment gradually
  compresses the lower layers and, along with
  chemical activity, turns them into rock.
• fossil formation

4
Radioactive Dating

• A half-life is the length of time required for
  half of the radioactive atoms in a sample to
  decay. (test question)

5
index fossil

• Scientists also use index fossils to compare the
  relative ages of fossils. To be used as an index
  fossil, a species must be easily recognized and
  must have existed for a short period but have had
  a wide geographic range. (test question)

6

• The first organisms on earth were most like
  todays bacteria. (test question)

7
Assignment

• Take five notes from the video
• Earth Science Fossils