From Wikipedia, the free encyclopedia. A teenager, or teen, is a young person whose age falls within the range from 13â19. They are called teenagers because their age number ends with teen. Usage by ordinary people varies, and also varies in different societies.
Astronomers and other scientists often speak of the extinction of dinosaurs on this earth. They believe that dinosaurs disappeared from the earth some 65 million years ago, long before man came along.They make these statements as if it were a known, proven scientific fact that dinosaurs were long gone by the time men appeared on the earth.hey believe that dinosaurs disappeared from the earth some 65 million years ago, long before man came along. They make these statements as if it were a known, proven scientific fact that dinosaurs were long gone by the time men appeared on the earth.
146 to 65 million years ago. 1  Pangaea continued to separate into smaller continents. 2  A wide variety of dinosaurs roamed the land. 3  Birds flourished and spread all over the globe. 4  Flowering plants developed. 5  Mammals flourished. 6  Dinosaurs became extinct by the end of the period. The extinction, the second largest of all time, marked the end of the Age of Reptiles and the beginning of the Age of Mammals. Dinosaurs that lived during the Cretaceous period include: