Image copyright The Field Museum, photo by James Balodimas
For many years people have often wondered about Dinosaurs. From our childhood they have always fascinated us. Creatures of a time from long before humans, remembered and studied today. Dinosaurs have become one of the more popular interests of our time.
Dinosaurs came approximitly 230 million years ago. They came about in the Triassic period of the Mesozoic era, the same time period in which some of the early mammials came about. The term Dinosaur means "terrible lizards", as stated by Sir Richard Owen in 1842. At this time the only dinosaurs known of were the Megalosaurus, Iguanodon, and Hylaeosaurus. Dinosaurs are very diverse creatures that lived for over 165 million years.
Dinosaurs are separated into two major groups. The groups are determined according to the dinosaurs hip shape. The Ornithischia, "bird hipped", tend to be herbivours (plant eaters). The Saurischia, "lizard hipped", tend to be meat eaters.
The Ornithischia contains several different groups of dinosaurs. The horned dinosaurs, armored dinosaur, small bipedal dinosaurs, and the duck billed dinosaurs.
The Saurischia contains three groups: the Prosauopoda, the sauropoda, and the theropoda.
Image copyright The Field Museum, photo by James Balodimas GEO-85733.7c
In the Jurassic (208-144 million years ago) some of the biggest dinosaurs evolved. This is also the time in which birds evolved.
The Cretaceous (144-66.4 million years) is when dinosaurs divesify like never before. At the end of this period is when dinosaurs become extinct. There are many different therories on why this happened. Some say because of the rise of angiosperms (flowering plants) that the dinosaurs food source was depleted. Others say a rise in volcanic activity caused the death. One of the most popular theories is that a comet hit the earth at this time causing the death of many dinosaurs. People will probably argue the reson for extinction forever, but most agree on the time it happened.
For more information on dinosausr visit these links
Time periods at The Field Museum