Teresa Kirkland, Age 12., Of Dallas N.C., for her question:

When was the Cenozoic Era?

An era is a chapter of earth’s history lasting a few hundred million years. In the past three billion years or more, there have been five such lengthy eras. The last of them is the cenozoic era., meaning recent life. It is the chapter of earthts history in which we live and in which all the existing forms of life developed.

The Cenozoic Era began about 60 million years ago., which means that merely the first few paragraphs of its story have been written. It began when the alps and the high himalayas began to lift up their heads., as the last of the dinosaurs departed and the furry mammals became the dominant animals of the world.