1. Ocean Planet & The Great Migration
Life in the Paleozoic
Ocean Planet &
The Great Migration

2. Late
Middle
Paleozoic
Early
Myr

3. Vertebrate Evolution
From Pikaia to Cheney

4. Phylum Chordata Including Subphylum Vertebrata
Notochord
Nerve cord
Pharyngeal gill slits
Vertebrates
Vertebral column replaces notochord
& skull encloses brain

5. Phylogeny Reminder
Fish --> Amphibians --> Reptiles --> Mammals

6. Think in terms of common ancestors and speciation

7. Fish Phylogeny

8. Fish: Jawless Fish (Agnatha)
Cephalasphid
Early Paleozoic ostracoderms. (A) Thelodus, (B) Pteraspis, (C) Jamoytius, and (D) Hemicyclaspis, drawn to the same scale.

9. Modern Agnatha: Sea Lamprey

10. Origin of Jaws

11. Fish: Armored Fish (Placoderms)
Dunkleosteus
Bothriolepis
Extinct

12. Fish: Armored Fish (Acanthodians)
Armor - a form of phosphorus storage?
Extinct
Acanthodes

13. Fish: Chondrichthyes (Cartilaginous Fish)

14. Modern Chondrichthyes (Sharks & Rays)

15. Fish: Osteichthyes (Bony Fish)

16. Osteichthyes: Ray Fined
Subclass: Actinopterygii
Rays

17. Ray Finned Fish
Sturgeon
Longnose Gar

18. Ray Finned Fish: Teleosts
Weedy Sea Dragon
96% of today’s fish
Zebrafish

19. Osteichthyes: Lobe Finned
Subclass: Sarcopterygii

20. Lobe Finned Fish
Coelacanth

21. Lobe Finned Fish
Lungfish
Eusthenopteron

23. The Great Migration (Silurian/Devonian)
Plants, Insects,
Vertebrates (Tetrapods)

24. Amphibians

25. Amphibians
Wood Frog Eggs

26. Lobe Fins to Amphibians

27. Acanthostega (Upper Devonian)

28. Ichthyostega (Upper Devonian)

29. Advantages to Moving onto Land
Lots of light for photosynthesis
Easy access to oxygen and carbon dioxide
Less competition
Rich source of nutrients an (eventually) food
Fewer predators

30. Challenges to Moving onto Land
Conserving water - not drying out
Obtaining & circulating water, food & gases
Overcoming gravity
Reproduction
Exposure to UV

31. Vertebrate Solutions Conserving water - not drying out
Obtaining & circulating water, food & gases
Overcoming gravity
Reproduction
Exposure to UV
Leathery skin & scales
3 or 4 chambered heart
Modified skeletal arrangement
Internal Fertilization & Amniotic Egg

32. Amniotic Egg Encloses embryo in water
Regulates oxygen.carbon dioxide exchange
Amniotic Egg
Food
Collects wastes
= Freedom from Oceans

33. Permian Reptile Egg

34. Modern Reptile Skin

35. The Amniotes Classified based on skull structure
Diapsids
(Includes lizards,
dinosaurs & birds))
The Amniotes Classified based on skull structure
Synapsids (Includes mammals)
Anapsids (Includes turtles)

36. Amniote Cladogram
About 300 Myr

37. Anapsids & Diapsids (True Reptiles)
Early Permian - Labidosaurus

38. Anapsids & Diapsids (True Reptiles)

39. Early Synapsids (Mammal-Like Reptiles)

40. Pelycosaurs (Sail Fins)
Temperature control?
Dimetrodon

41. Therapsids (Permian Synapsids)
Dicynodonts
Cynodont

42. More on Synapsid, Mammal, and Reptile Evolution in the Mesozoic…