Book excerpt: Reptiles and amphibians ruled the world for nearly 200 million years and today there are still over 12,500 of them. Some are huge, the deadliest creatures on earth. Some are tiny, among the strangest to be found anywhere. Together they not only outnumber mammals or birds but in their colourful variety and extraordinary behaviour, they far surpass them.So where did these ancient creatures come from? How have they transformed themselves into the bizarre and beautiful forms that are alive today? And what's the secret of their epic success? In Life in Cold Blood, David traces the story of their evolution and overturns the myth that these creatures are just primitive killers to reveal them for what they truly are.