Chapter 30

What changes took place in the second stage of development? 3. What is the form by the middle of the Tertiary period? 4. What was the size of the late Tertiary horse, and how was the grinding power of the teeth increased? 5. How was the early Quaternary horse adapted for speed and for eating? 6. How is the extermination of the horse in North and South America accounted for, and how was he introduced again?