Introduction to The Emergence of Primates
Around 65 million years ago, at the end of a time called the Cretaceous Period, life on Earth was in the midst of a great transformation. This prehistoric world was warm and teeming with dense forests and lush wetlands filled with a rich variety of plants and animals, including the last of the dinosaurs. Conifers (cone-bearing plants) had been the dominant type of plant for more than 100 million years, but angiosperms (flowering, fruit-bearing plants) were beginning to spread. With angiosperms came new forms of life—new species of insects that lived off flower nectar and fruits and other kinds of animals that ate the flourishing insects and other foods in the lush forests. One of those animals may have been a hairy little shrewlike creature that scurried across the floor of the forests. This mysterious animal may have been the ancestor of all primates, a group of related animals that includes apes, monkeys, and human beings.
Exactly what sort of creatures the first primates were is uncertain, but they were probably small—less than 20 centimeters (8 inches) long—and they might have looked like miniature squirrels, perhaps with long snouts. They probably had some, but not all, of the characteristics of present-day primates. For over a century, paleontologists (scientists who specialize in ancient life) have studied fossils of early primates and their close relatives. They have generated many ideas about the early primates, but few conclusions.