The Name: The name dinosaur comes from the term Dinosauria, which means terribly great lizards. But dinosaurs were not lizards, only distantly related to them, and most were not very terrible.
Dino Intelligence: One of the most intelligent dinosaurs was a small, bipedal theropod called Troodon. Troodon‘s brain was as large, compared with its body weight, as that of many modern birds and small mammals. It had excellent vision and probably hunted for mammals and other prey at night.
Millions of Years: Dinosaurs lived throughout most of the Mesozoic Era, which is divided into three periods—Triassic, Jurassic, and Cretaceous. The Triassic Period lasted from about 250 million to 200 million years ago. The Jurassic Period lasted from about 200 million to 145 million years ago, and the Cretaceous Period from about 145 million to 65 million years ago.
From Birth To Death: Scientists do not know how all dinosaurs reproduced and can only guess how long dinosaurs lived. Fossil dinosaur eggs show that at least some dinosaurs laid hard-shelled eggs, as do modern alligators. They can estimate the time it took for dinosaurs to grow to adult size; studies of the microscopic structure of dinosaur bones suggest that dinosaurs grew rapidly.
Very First Findings: Before the 1800’s, no one knew that dinosaurs had ever existed. People who found a dinosaur tooth or bone did not know what it was. However, around 1818, an English scholar, William Buckland, obtained a large lower jaw that contained a number of sharp teeth. After studying this jaw, Buckland came to the conclusion that it was unlike any fossil previously discovered. So he gave it a new name, Megalosaurus(great lizard), in 1824.
The Mysterious T-Rex: Early scientists first thought this giant meat-eater was primarily a scavenger, feeding only on the decaying bodies of dead dinosaurs. They also thought it lived a sluggish life, sleeping or basking in the sun between meals. However, scientists gradually came to believe that Tyrannosaurushad a much more dynamic lifestyle and argue that it was an active predator as well as a scavenger.
The Disappearance: There are many developed theories that explain dinosaur extinction. Two of the major theories involve 1) the collision of an asteroid with Earth and 2) large volcanic eruptions in what is now India.