Trilobites: Finding the Speed of Evolution in a Study of Bird Beaks

When the ancestors of Darwin’s finches arrived on the Galápagos two million years ago, they gained access to a world of new morsels, untapped by other animals. In a relatively short period, 14 species of finches evolved, specializing in different diets through different beak shapes: short for crushing seeds, sharp for catching insects, long for probing cactus flowers and so on.