1. Amphibians and Reptiles

2. The Move to Land
Respiration
Locomotion
Prevent water loss

3. Circulation and Respiration
Fish
Gills
Transfer from water
Single loop circulatory system
Two chambered heart
Amphibian/reptile
Lungs
Transfer from air
Double loop circulatory system
Pulmonary
Systemic
Three chambered heart

4. Evolution of Lungs

5. Heart Structure Fish Amphibian and Reptile To gills From body
To body and lungs
From body
From lung
Amphibian and Reptile

6. Evolution of Limbs Early lobe finned fishes Early tetrapods
Move from pond to pond
Move along bottom of stream or pond
Early tetrapods
Walked on bottom of streams and ponds
Limited walking on land
Early amphibians
Fully terrestrial adult

7. Early Lobe Finned Fishes
Move from pond to pond
Move along bottom of stream or pond
Pectoral girdle attached to skull
Arm bones present
Humerus, ulna, radius

8. Early Tetrapods Walked on bottom of streams and ponds
Limited walking on land
Fin rays replace by phalanges
Wrist bones
Pectoral girdle separated by neck bones
Some had ribcage

9. Early Amphibians Fully terrestrial adult
Pentadactyl (5 phalanges) limbs
Arm structure very similar to modern tetrapods

10. Homologous Limb Structures

11. Water Loss Amphibian skin water permeable
Must remain moist
Respiration occurs at skin – highly vascularized
Amphibian eggs gelatinous, no cover to protect from desiccation
Larval form lives in water
Adult lives in moist environment

12. Amphibian Orders Order Gymnophiona Order Caudata (salamanders)
Legless burrowing
Order Caudata (salamanders)
Aquatic larva stage
Internal fertilization
Larva and adult carnivorous
Order Anura (frogs and toads)
Metamorphosis
External fertilization
Larva herbivorous, adult carnivorous

13. Adaptations for Living on Dry Land
Amniotic egg
Leathery shell
Amniotic membrane
Retains fluid in egg
Lung breathing young
Internal fertilization
Water proof skin
Kidneys can reabsorb water

14. Amniotic Egg

15. Amniotes

16. Amniote Skulls

19. Reptile Skin