1. Earth: Geologic Principles and History FIRST EDITIONCHERNICOFF/FOX/TANNER

2. Chapter 22 Paleozoic Life

3. Copyright © by Houghton Mifflin Company. All rights reserved.3 Figure 22.17a: Graptolites

4. Copyright © by Houghton Mifflin Company. All rights reserved.4 Figure 22.19a: Halysites

5. Copyright © by Houghton Mifflin Company. All rights reserved.5 Figure 22.20: Stromatoporoids

6. Copyright © by Houghton Mifflin Company. All rights reserved.6 Figure 22.31 a: Lepidodendron

7. Copyright © by Houghton Mifflin Company. All rights reserved.7 Figure 22.31 b: Calamites