BCB705 Biodiversity: Chapter2 - Evolution of Biodiversity

Table of Contents

1. THE INFINITE VARIETY: THE BEGINNING OF LIFE
2. BUILDING BODIES: INVERTEBRATES OF THE OCEANS
3. THE FIRST FORESTS
4. THE SWARMING HORDES
5. THE CONQUEST OF THE WATER AND THE BIRTH OF THE VERTEBRATES
6. THE INVASION OF THE LAND
7. A WATER-TIGHT SKIN AND THE SHELLED EGG
   1. Issues: Ectothermy vs Endothermy
   2. Breeding mechanisms of the ancestral reptile
   3. Skull structure
   4. The Anapsids
   5. The Diapsids
   6. The Synapsids
   7. First dinosaur characteristics
   8. Dinosaur fossils
   9. Gigantic herbivores and carnivores
   10. Temperature regulation limits energy use
   11. The beginning of the end for the kings
   12. Impressive parental care
   13. Conquering various living environments
   14. The flight of the dinosaur
   15. The Pterosaur: The take-off
   16. The Ptesosaurs: Not just a gliding motion
   17. The extinction
   18. Mammals' role in extinction
   19. Change in climate
   20. Crocodiles
   21. Crocodiles: Social life
   22. The Order Chelonia: Modified
   23. The lizard
   24. Modifying the scales
   25. Limb reduction
   26. Snakes
   27. Snakes: Making waves
   28. Snakes: The predator
   29. Snakes: Nurturing the young
   30. Snakes: The nocturnal hunter
   31. Test Yourself
   32. Assignments
8. LORDS OF THE AIR
9. EGGS, POUCHES AND PLACENTAS
10. THEME AND VARIATION
11. THE HUNTERS AND THE HUNTED
12. A LIFE IN THE TREES
13. THE COMPULSIVE COMMUNICATORS

A WATER-TIGHT SKIN AND THE SHELLED EGG

From amphibians to reptiles

The reptiles evolved from an early ancestral group of amphibians (Subclass Labyrinthodontia) which have been extinct for 175 million years. Terrestrial Labyrinthodontia had strong limbs, robust bodies. The first animal with a dry skin was probably Seymouria which lived in the Permian (230 million years ago) is thought to be the link between the amphibians and the reptiles and was probably the first animal to have a hard-shelled egg that entirely freed its reproduction from water or extremely moist habitats. All amphibians require a moist environment to survive and reproduce, but the reptiles can occupy a dry environment due to their water-tight skin and the shelled eggs.

Labyrinthodontia