The study of history of life based on fossils
Many people assume paleontology is the study of fossils or the study of history of life, when in actuality it's a combination of the two. Paleontology incorporates many other fields of science, such as biology, archeology, and geology.
The two main groups of dinosaurs are saurichians, or "lizard-hipped," and ornithischians, or "bird-hipped."
The Mesozoic Era
The Protozoic and Paleozoic eras predate the Mesozoic Era, and the Cenozoic era followed after.
ApatosaurusVia ThinkstockStegosaurusVia ThinkstockThrinaxodonHumansVia Thinkstock
The Tyrannosaurus Rex evolved around 67 million years ago during the late Cretaceous period. Dinosaurs like the Apatosaurus and Stegosaurus evolved around 150 million years ago, putting significantly less time between us and the T-Rex.
GastornisVia ThinkstockGigantoraptorVia ThinkstockElasmosaurusVia ThinkstockPteranodonVia Thinkstock
This 10-foot-tall, 30,000-pound feathery giant definitely lives up to its name. Though the Gigantoraptor is very bird-like with its beak and feathers, it is still considered a dinosaur.
The first Stegosaurus was discovered in Colorado in 1877.
A mass extinction event
252 million years ago, 76 percent of all marine and land life were wiped out. Though the cause of the mass extinction is still under debate, it did pave the way for dinosaurs to dominate the earth throughout the Jurassic period.
TriceratopsVia ThinkstockVelafronsVia ThinkstockCorythosaurusVia ThinkstockByronosaurus
Yup, this is the Byronosaurus. It liked meat, and those other dinosaurs did not.
Triassic, Jurassic, Cretaceous
The Triassic period occurred between 251 and 205 million years ago, the Jurassic between 205 million and 144 million years ago, and the Cretaceous period between 144 million and 65 million years ago.
165 million years
A very, very, very long time.