Holt Modern Biology 1st Edition by John Postlethwait ,Janet Hopson

Exercise 17

Interpreting Graphics The graph below shows the diversity among different groups of animals over time. Of the four eras listed, the Cenozoic era is the most recent. The changing width of the bar for each group reflects the changing number of known subgroups over geologic time. Use the graph to answer the following questions:
A. Which group most recently evolved?
b. Which group is or was the most diverse? The least diverse?
c. Which group diversified rapidly soon after it first appeared?
d. Which group(s) became extinct?