1. Chondrichthyes
Sharks, skates and rays
Placoid scales
Ampullary organs

2. Placoid scales and drag

3. Chondrichthyes No swim bladder for buoyancy big liver loss of weight
lift from tail, pectoral fins

4. Heterocercal vs. Homocercal tails

6. Teeth in shark originate from modified placoid scales
Enamel
Dentine
‘Denticles’

7. Denticles
Placoid scales
Teeth

8. Chondrichthyes
Septal gill design

10. Phylum Chordata
Subphylum Urochordata (Tunicata)
Subphylum Cephalochordata
Craniata group
Subphylum Vertebrata
Superclass Agnatha
Superclass Gnathostomata
Class Placodermi
Class Chondrichthyes
Class Acanthodii
Class Osteichthyes
Class Amphibia
Class Reptilia
Class Mammalia
Class Aves

11. Osteichthyes
“Bony fish” By far the most diverse class. Swim bladder (or gas bladder) present in in most species

12. Swim bladder

13. Opercular gills - bony covering overlying gill slits

14. Some major groupings in Osteichthyes
Actinopterygii
Teleostei
Sarcopterygii
Dipnoi
Crossopterygii

15. 2 major groups: Actinopterygians - ray-finned fish
dominant form presently
fins move via muscles in body wall
fins w/ Lepidotrichia

16. Actinopterygii Teleosts - diverse group of Actinopterygians
Recent radiation - 65 million years ago
Has a derived swim bladder design (detached from gut)

17. Sarcopterygians - fleshy-finned fish
Thicker fins - muscles within fins
Swim bladder connected to gut (ancestral)
Internal nostril (choana) first arose in this group
fossil sarcopterygian w/choana
Early choanates

18. Sarcopterygii Dipnoi - lungfish Paired lungs
Survive in mud by breathing air.
In warm waters - not as much dissolved oxygen

19. Sarcopterygii Crossopterygii -
Several fossil forms with swim bladders used as “lungs”
One living - Coelacanth

20. Homologies with Amphibia
Crossopterygii
Homologies with Amphibia
Bones in fins correspond to bones in early tetrapods
Labyrithodont teeth

21. Crossopterygian and Labyrinthodont skulls

23. Crossopterygian fish
Early tetrapod

24. Fossil organisms showing a fish/tetrapod transition
Acanthostega
Tiktaalik roseae
“Labyrinthodont” group

25. Actinopterygii - Ray-finned Sacropterygii - fleshy-finned

26. Tetrapods Phylum Chordata Subphylum Urochordata (Tunicata)
Subphylum Cephalochordata
Craniata group
Subphylum Vertebrata
Superclass Agnatha
Superclass Gnathostomata
Class Placodermi
Class Chondrichthyes
Class Acanthodii
Class Osteichthyes
Class Amphibia
Class Reptilia
Class Mammalia
Class Aves
Tetrapods

27. From water to land:

28. From water to land:
“Problems”:
Support - Air is a thinner medium.

29. From water to land:
“Problems”: Support - Air is a thinner medium. Gas exchange - Oxygen in a different state.

30. From water to land:
“Problems”: Support - Air is a thinner medium. Gas exchange - Oxygen in a different state. Temperature - Fluctuates more in air.

31. From water to land: “Problems”: Support - Air is a thinner medium.
Gas exchange - Oxygen in a different state.
Temperature - Fluctuates more in air.
Keeping moist - How to keep tissues, eggs, young moist?

32. Fossil amphibians

34. Amphibia - have aquatic larval stage
Toads and Frogs (Anura)
Salmanders (Urodela)
Caecilians (Gymnophiona)

35. Tetrapods Amniotes Phylum Chordata Subphylum Urochordata (Tunicata)
Subphylum Cephalochordata
Craniata group
Subphylum Vertebrata
Superclass Agnatha
Superclass Gnathostomata
Class Placodermi
Class Chondrichthyes
Class Acanthodii
Class Osteichthyes
Class Amphibia
Class Reptilia
Class Mammalia
Class Aves
Tetrapods
Amniotes

36. Amniotes Amniotes - have embryos with extra-embryonic membranes
amnion keeps water from leaving the egg or developing young.

37. Major living ‘reptile’ groups:
Lizards and snakes (Squamata)
Crocodiles and alligators (Crocodilia)
Turtles (Testudinata)

38. Aves Most diverse class of tetrapods Feathers modification of skin
thermoregulation, flight

39. Microraptor gui

41. Endothermy Puts particular requirements on some physiological systems:
Circulatory, respiratory systems must be efficient and work at high rates

43. Mammalia Defining characteristics: Hair - for insulation, sensation.
Mammary glands
Other glands - sweat and sebaceous glands.

44. Distinguishing mammal from reptile fossils
Via fossil evidence:
1. Three bones make up middle ear: malleus, incus, stapes
Theraspid

45. Distinguishing mammal from reptile fossils
2. Lower jaw a single bone (dentary) 3. Jaw joint is articulation of dentary and squamosal bone.

46. Major mammal groups:
Monotremes - oviparous

47. Therians - viviparous
Marsupials - partial internal - external development

48. Therians - viviparous
Placentals (eutherians) - completely internal development - Most diverse