Problem 21
Describe how the diversity of reptiles changed through time.
Problem 21
Infer Use the outlines of the present-day continents to make a sketch of Pangaea.
Problem 22
Form Hypotheses Suggest some reasons why trilobites might have become extinct at the end of the Paleozoic Era.
Problem 23
Why might mammals in Australia be so much different than mammals on other continents?
Problem 24
Describe how natural selection might cause a species to change through time.
Problem 25
How did early photosynthetic organisms change the conditions on Earth to allow more advanced organisms to flourish?
Problem 26
What are mass extinctions? How have they affected life on Earth?
Problem 27
Write a description of what Earth was like during Precambrian time. Summarize how Earth was different than it is now.
Problem 28
The Cenozoic Era has lasted 65 million years. What percentage of Earth's 4.5-billion-year history is that?
