Activity 4A

Life Time Line

Students complete a time line showing the appearance and extinction of major types of fauna. Students also make forecasts into the future using time lines (see The People's Time Line in the History section).


  • Students will be able to visualize the times of important evolutionary events in relation to geological and cultural history.
  • Students will be able to name some of the animals that became extinct at Craters of the Moon.
  • Students will use their imaginations to forecast future events and designate them on a time line.


2 hours.


Of the millions, perhaps billions, of species that have lived on Earth, only a tiny fraction are alive today. Many (but not all) scientists think that mass extinctions were caused by asteroids crashing into Earth. The age of dinosaurs passed 65 million years ago and growing evidence shows that it coincided with an asteroid that struck the Earth in what is now the West Indies. Other extinctions were caused by changing weather regimes and competition with species that occupied similar niches. In all cases, however, a species becomes extinct because it cannot adapt to changing circumstances.

The Earth is currently undergoing one of its most accelerated periods of extinction. Unlike all other known extinction phases, a single species, humans, is responsible. Species which are not able to adapt to human-caused changes are becoming extinct daily.

Perhaps if we become more knowledgeable about our evolutionary history, our concern for the species with which we share the Earth will grow.


  • Adding machine tape (3 or 4 inches wide by about 100 feet).
  • Pencils, pens, crayons.
  • String or yarn.
  • Use of a large indoor wall while your class is studying about Craters of the Moon.
  • Several picture books on prehistoric life.


We recommend that you first conduct the People's Time Line activity in the Cultural History section.

Part I - Life Time Line

Have the students make a time line showing the major biological features of several geologic periods.
  • Choose several students to make a time line about 15 feet long.
  • Label the right side "present" and the left side "500,000,000 years ago." Divide the time line into five 100,000,000 year increments. Divide each of these into ten 10,000,000 year increments.
  • Label it "Life Time Line" and affix it to the wall above the Earth's Time Line and below the Craters of the Moon Time Line.
  • Teams of students (2-3 each) should make the following labels on separate small pieces of paper and tape them at the appropriate place to the Life Time Line. The students should label the range of time indicated on the Life Time Line.
  • Teams should illustrate their geologic period with representative life forms by looking at various picture books on dinosaurs and prehistoric life.

Period Time Span Events

Quaternary Present to 3 million years ago. Humans evolve.
Tertiary 3 million to 63 million years ago. Mammals are abundant and diverse and are the dominant animal life form.
Cretaceous 63 million to 135 million years ago. Extinction of dinosaurs and ammonites (flat spiral shellfish) at end of Cretaceous. First flowering plants evolve.
Jurassic 135 million to 180 million years ago. First birds and mammals evolve. Age of dinosaurs and ammonites.
Triassic 189 million to 230 million years ago. First dinosaurs. Abundant conifers (pine-like trees). Abundant cycads (like giant ferns).
Permian 230 million to 280 million years ago. Extinction of many marine animals, including trilobites.
Carboniferous 280 million to 345 million years ago. First reptiles. Sharks and amphibians abundant. Large primitive trees and ferns.
Devonian 345 million to 405 million years ago. First amphibians. Fishes abundant.
Silurian 405 million to 425 million years ago. First land plants. First land animals.
Ordovician 425 million to 500 million years ago. First fishes. Many invertebrates.


Part 2 - Craters Life Labels

Have the students make and illustrate the following labels and attach them to the People's Time Line.
  • by 1920, bighorn sheep known to be extinct at Craters.
  • by 1920, elk known to be extinct at Craters.
  • by 1920, wolf known to be extinct at Craters.
  • by 1920, grizzly known to be extinct at Craters.
  • by 1840, bison known to be extinct in southern Idaho.

Part 3 - Future Time Line

Give each student about one or two feet of time line and instruct them to make a time line into the future using whichever time scale they want. For example, their time line could go from "Present" to "2 million years from now" or only "10 years from now." Students illustrate their time line with words and pictures explaining their predictions of the future.

Part 4 - Link Time Lines

Link the four time lines on your wall with string or yarn to show the temporal relationships between them. For example,

Activity 4B - 4C - 4D | Table of Contents | Chapter 1 - 2 - 3 - 4 - 5

Last updated: February 28, 2015

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