Connecting Concepts

Use Science Graphics

The chart below shows the relative numbers of species in four groups of vertebrates over time. The thickness of each band shows the relative number of species in that group. Use the chart to answer questions 27–30.

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27. Compare and Contrast How is this kind of diagram similar to a traditional cladogram? What additional information can be learned from it?

28. Interpret Visuals Which of the groups shown has the greatest number of species today?

29. Infer Archosaurs are a group of reptiles that includes the dinosaurs, pterosaurs, modern crocodiles, and birds. Why do you think that birds are shown separately from the other archosaurs in the diagram?

30. Apply Concepts Describe the trend for each group shown from the beginning of the Mesozoic to today. Which groups were affected by the mass extinction at the end of the Mesozoic? Which groups have experienced adaptive radiations?

Write About Science

31. Explanation Write a paragraph in which you describe, in your own words, what the first animals were like.

32. Description In a paragraph, describe in your own words when the dinosaurs went extinct and what events contributed to the extinction.

33. Explanation Why is it important to estimate the age of a hominine fossil as well as to analyze its structural characteristics?

34. Assess the Life on Earth began in water. What were some of the major adaptations that animals evolved that allowed them to survive out of water?

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