Dinosaurs | Dinosauria
Dinosaurs are a diverse group of prehistoric reptiles that were the dominant terrestrial animals of the Late Triassic (251.9-201.3 Mya), Jurassic (201.3-145 Mya), and Cretaceous (145-66 Mya) periods. Discovered and studied since the 19th century, dinosaur fossils found around the world have been used by paleontologists to identify over 1,000 different species of dinosaurs. Dinosaurs are commonly categorized by distinctive traits ranging from variations of bipedal (2 legs) or quadrupedal (4 legs), body armor or feathers, herbivorous or carnivorous, and quick or slow movement speeds. Though dinosaurs mysteriously disappeared 65 million years ago, their legacy continues to be popularized in museums, books, films and television.
Dinosaurs lived in the Mesozoic Era which took place between 245 and 66 million years ago. The Mesozoic Era is divided into 3 time periods: Triassic (252 to 201 million years ago), Jurassic (201 to 145 million years ago), and Cretaceous (145 to 66 million years ago).
Paleontologist believe dinosaurs grew so big in order to gain protection from predators, help regulate internal body temperature, and to allow them to reach their source of food. Today, whales are the only animal who are close to the size of dinosaurs.
Dinosaur fossils have been found on every continent, proving that they lived in every environment of the world. During the Triassic period the continents were one supercontinent called Pangea. The continents slowly spread across the world into the arrangement that they are at today.