1. Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies History Of The Vertebrates Chapter 20 Copyright © McGraw-Hill Companies Permission required for reproduction or display

2. Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies Outline Paleozoic Era Mesozoic Era Cenozoic Era Fish Dominate the Sea  Bony Fish Amphibians Invade the Land Reptiles Conquer the Land Birds Master the Air Mammals Adapt to Colder Climates

3. Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies Paleozoic Era Earth’s past divided into eras.  Subdivided into periods. - Subdivided into epochs.  Subdivided into ages.  Virtually all major surviving groups of animals originated in the sea at the beginning of the Paleozoic Era. - First vertebrates (jawless fish) evolved 470 million years ago.

4. Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies

5. Paleozoic Era Terrestrial Invasions  First - plants (410 mya).  Second - arthropods.  Third - vertebrates. Mass Extinctions  Four occurred during Paleozoic. - Estimated 96% of all marine species went extinct.  Vacant niches allowed rapid evolution.

6. Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies Mesozoic Era Time of intensive evolution of terrestrial plants and animals.  Amphibians followed by reptiles. - Evolved into three great lines of terrestrial vertebrates:  Dinosaurs, Birds, Mammals  Dinosaurs dominated for over 150 million years.

7. Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies Mesozoic Era Traditionally divided into three periods:  Triassic  Jurassic  Cretaceous - Dinosaurs disappeared about 65 mya at end of the Cretaceous.  Mammals quickly evolved and rose to dominance.

8. Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies Mesozoic Era Disappearance of Dinosaurs  Most widely accepted theory blames asteroid collision. - Alvarez Hypothesis - Large meteorite impacted earth, sending dense cloud of debris into atmosphere, temporarily halting photosynthesis.  Large impact crater discovered off coast of Yucatan peninsula.

9. Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies Extinction of Dinosaurs

10. Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies Cenozoic Era First half of Cenozoic was very warm with jungle-like forest at the poles. As glaciation in Antarctica became fully established about 13 mya, regional climates cooled dramatically.  Evolution of many large mammals.

11. Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies Vertebrate Family Tree

12. Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies Fish Dominate the Sea Fish comprise about half of all vertebrates.  Characteristics - Gills - Vertebral Columns - Single-Loop Circulation - Nutritional Deficiencies  Aromatic Amino Acids

13. Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies Fish Dominate the Sea Jawless fish ostracoderms, appeared about 470 mya.  Eventually replaced by hunters. - Agnathans (hagfish and lampreys) Evolution of Jaws  Addressed two marine challenges: - How to grab and hold prey - How to pursue prey  Seem to have evolved from arch supports.

14. Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies Evolution of Jaws

15. Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies Fish Dominate the Sea Sharks  Class Chondrichthyes replaced heavy bony skeleton with lighter flexible, cartilage. - Skates and rays are flattened sharks that evolved about 200 mya. - Complex Reproduction System  Shark eggs fertilized internally.  About 40% lay fertilized eggs.

16. Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies Fish Dominate the Sea Bony Fishes  Adopted heavy internal bone skeleton to provided base for strong muscles to attach.  Swim bladder regulates buoyant density.  Lateral Line System detects water pressure changes.  Operculum covers and pumps water over gills. Most successful of all vertebrates.

17. Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies Bony Fish

18. Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies Amphibians Invade the Land First vertebrates to walk on land.  Evolved from lobed-finned fish. Characteristics  Legs  Cutaneous Respiration  Lungs  Pulmonary Veins  Partially Divided Heart

19. Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies Evolution of Legs

20. Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies Reptiles Conquer the Land Characteristics  Amniotic Egg  Dry Skin  Thoracic Breathing Legs arranged to more effectively support body weight.

21. Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies Reptilian Watertight Eggs

22. Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies Reptiles Conquer the Land History  Pelycosaurs - Therapsids  Thecodonts  Dinosaurs  Crocodiles  Icthyosaurs  Pleiosaurs  Pterosaurs

23. Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies Birds Master the Air Evolved from small bipedal dinosaurs about 150 mya. Distinguishing Characteristics  Feathers  Thin, hollow flight skeleton History  Oldest bird fossil - Archaeopteryx - Solid bones

24. Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies Feathers

25. Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies Mammals Adapt To Colder Climates Evolved about 220 mya at same time as dinosaurs.  Shared three characteristics with modern mammals: - Mammary Glands - Hair - Middle Ear

26. Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies Mammals Adapt To Colder Climates History  Arose from therapsids in mid-Triassic. - May have been nocturnal.  Subclass Prototheria - Laid shelled eggs.  Monotremes - Duck-Billed platypus  Subclass Theria - Live born  Marsupials and Placental Mammals

27. Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies Mammals Adapt To Colder Climates Other Characteristics of Modern Mammals  Endothermic  Placental  Specialized Dentition

28. Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies Review Paleozoic Era Mesozoic Era Cenozoic Era Fish Dominate the Sea  Bony Fish Amphibians Invade the Land Reptiles Conquer the Land Birds Master the Air Mammals Adapt to Colder Climates

29. Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies Copyright © McGraw-Hill Companies Permission required for reproduction or display