Introduction:
In part A of this activity you will fill in a chart of the Geologic Time Scale with some of the significant
organisms that have evolved on the planet Earth. In constructing an evolutionary history geologists and
evolutionary biologists find it important to know the geologic range of organisms. This is the time when an
organism first appears in the fossil record and when it becomes extinct. Many scientists also find it
instructive to note the time period when certain groups of organisms were most abundant or were dominant.
In part B of the activity you will construct a time line that is a scale model of the time scale that will show
the relative amount of time of the events you are recording
Materials:
Blank Geologic Time Scale
Meter stick or ruler
Adding-machine tape
Procedure:
Part A
1. Use any resources to place the following events in their proper time periods in the Geologic Time Scale
chart
a. Humans appear
b. First land plants
c. First fish
d. First insects
e. First dinosaurs, mammals
f. Primates appear
g. Extinction that wiped out 95% of all species
h. First reptiles
i. First birds
j. Age of Trilobites
k. The Earth forms
l. First multicellular organisms
m. First eukaryote
n. Age of Fishes
o. First prokaryote
p. Age of Reptiles
q. First flowering plants
r. First grasses
s. First organisms with hard parts
t. First amphibians
u. Age of Mammals
v. Extinction that killed the dinosaurs
w. Oxygen starts to accumulate in atmosphere
Part B
1. Use a meter stick to draw a continuous line down the middle of a 5 m strip of adding-machine tape. Use
a scale of 1 meter equals 1 billion years. . Each millimetre then represents 1 million years
2. At one end of the tape, draw a vertical line and label it “the Present”.
3. Measure off the distance that represents 4.6 billion years (b.y.) ago. Draw a vertical line at that point
and label it “Earth’s Beginning”
4. Using the Geologic Time Scale chart:
a. Plot each era and period; write the name to the left of the line
b. Plot each event on your time line; put the “earliest or first occurrence of” evidence to the right of the
line.
c. Draw in coloured pencil an example of the major organisms to evolve for each period.
Analysis: Put answers on the back of your Geologic Time Scale sheet
1. Which era is longest? The shortest?
2. In which eras and periods did dinosaurs, mammals, flowering plants and birds appear on Earth?
3. Which lived on Earth the longer time, dinosaurs or mammals? Calculate the range of time for each.
4. What major group flourished only after the dinosaurs became extinct? How do you know?
5. Where did life exist during the early part of the Palaeozoic Era? What fossil evidence leads to this
conclusion?
EON
ERA
PERIOD
QUATERNARY
YEARS AGO BP
CENOZOIC
2 my
TERTIARY
65 my
CRETACIOUS
146 my
JURASSIC
MESOZOIC
210 my
TRIASSIC
245 my
PERMIAN
290 my
PENNSYLVANIAN
325 my
MISSISSIPPIAN
360 my
DEVONIAN
410 my
SILURIAN
500 my
CAMBRIAN
544 my
3800 my
3.8 billion yr
PRECAMBRIAN
2500 my
2.5 billion yr
HADEAN
PROTERO
ZOIC
PALEOZOIC
ORDIVICIAN
ARCHEAN
PHANEROZOIIC
440 my
4600 my
4.6 billion yr
EVOLUTIONARY EVENT