Why there are so many species of serpent

THE CAENOZOIC—the era of Earth’s history since an asteroid strike 66m years ago ended the dinosaurs’ reign—is often called the age of mammals. And mammals did, indeed, do well in the scramble to fill the ecological niches suddenly vacated by that catastrophe, for there are now about 6,500 species of them. But several other groups were equally, if not more successful. Birds (technically dinosaurs, too, by ancestry, though few think of them that way) have about 11,000 species. Lizards have 7,000.And there is yet another set of terrestrial vertebrates that prospered post-impact, but which are sadly neglected by zoologists. These are snakes. With almost 4,000 representatives, they are not as speciose as mammals. But they are not far behind.