Dimetrodon

2. 1 m 100 mya Rhomaleosaurus victor 175 200 0.5 m Dimetrodon 270 Tiktaalik 300 4.5 cm 375 Coccosteus cuspidatus 400 1 cm Hallucigenia 500 2.5 cm 510 Dickinsonia costata 560 Stromatolites 600 1,500 Tappania 3,500

3. 1 16 Accumulating “daughter” isotope ½ Fraction of parent isotope remaining Remaining “parent” isotope ¼ ⅛ 1 2 4 3 Time (half-lives)

4. Reptiles (including dinosaurs and birds) Key to skull bones Articular Dentary OTHER TETRA- PODS Quadrate Squamosal †Dimetrodon Early cynodont (260 mya) Synapsids †Very late (non-mammalian)cynodonts Temporal fenestra (partial view) Therapsids Cynodonts Mammals Hinge Synapsid (300 mya) Later cynodont (220 mya) Temporal fenestra Hinge Original hinge New hinge Therapsid (280 mya) Very late cynodont (195 mya) Temporal fenestra Hinge Hinge

5. † † † Lineage A † † Common ancestor of lineages A and B Lineage B † 0 4 3 2 1 Millions of years ago

6. Crust Mantle Outer core Inner core

7. North American Plate Eurasian Plate Juan de Fuca Plate Philippine Plate Caribbean Plate Arabian Plate Indian Plate Cocos Plate South American Plate Pacific Plate Nazca Plate African Plate Australian Plate Scotia Plate Antarctic Plate

8. Present Collision of India with Eurasia 45 mya Cenozoic Eurasia North America Present-day continents Africa 65.5 mya India South America Madagascar Australia Antarctica Laurasia Laurasia and Gondwana landmasses 135 mya Gondwana Mesozoic The supercontinent Pangaea Pangaea 251 mya Paleozoic

9. 1 2 2 1 Mantellinae (Madagascar only): 100 species Rhacophorinae (India/southeast Asia): 310 species 60 20 40 0 80 Millions of years ago (mya) India Madagascar 88 mya 56 mya

10. 1,100 1,000 25 900 800 20 700 600 15 Total extinction rate (families per million years): Number of families: 500 400 10 300 200 5 100 0 0 Mesozoic Paleozoic Era Period Cenozoic Q E O S D C P Tr J C P N 542 488 444 416 359 299 251 200 145 65.5 0 Time (mya)

11. NORTH AMERICA Chicxulub crater Yucatán Peninsula

12. Mass extinctions 3 2 1 Relative extinction rate of marine animal genera 0 −1 −2 −3 −2 −1 0 1 2 3 4 Cooler Warmer Relative temperature

13. Cretaceous mass extinction 50 Permian mass extinction 40 30 Predator genera (%) 20 10 0 Paleozoic Mesozoic Era Period Cenozoic E O S D C P Tr J C P N 542 488 444 416 359 299 251 200 145 65.5 0 Q Time (mya)

14. Ancestral mammal Monotremes (5 species) Marsupials (324 species) ANCESTRAL CYNODONT Eutherians (5,010 species) 250 200 150 100 50 0 Time (millions of years ago)

15. Close North American relative, the tarweed Carlquistia muirii KAUAI 5.1 million years Dubautia laxa 1.3 million years MAUI Argyroxiphium sandwicense MOLOKAI OAHU 3.7 million years LANAI HAWAII 0.4 million years N Dubautia waialealae Dubautia scabra Dubautia linearis

16. Chimpanzee infant Chimpanzee adult Chimpanzee fetus Chimpanzee adult Human fetus Human adult

17. Hand and finger bones

18. Gills

19. Hox gene 6 Hox gene 7 Hox gene 8 Ubx About 400 mya Drosophila Artemia

20. Results Result: No The 283 amino acids of the Pitx1 protein are identical. Hypothesis A: Differences in sequence Result: Yes Hypothesis B: Differences in expression Marine stickleback embryo: expression in ventral spine and mouth regions Lake stickleback embryo: expression only in mouth regions Red arrows indicate regions of Pitx1 expression.

21. (a) Patch of pigmented cells (b) Eyecup Pigmented cells (photoreceptors) Pigmented cells Epithelium Nerve fibers Nerve fibers Example: Pleurotomaria, a slit shell mollusc Example: Patella, a limpet (e) Complex camera lens- type eye (c) Pinhole camera-type eye (d) Eye with primitive lens Cornea Epithelium Cellular mass (lens) Fluid-filled cavity Cornea Lens Retina Optic nerve Optic nerve Optic nerve Pigmented layer (retina) Example: Murex, a marine snail Example: Loligo, a squid Example: Nautilus