Exploring the mysteries of Dinosaur Evolution

Saurischians diverged into Sauropodomorpha and Theropoda. The Sauropodomorpha evolved into herbivorous, quadrupedal dinosaurs which included the largest ever terrestrial animals. 

Ornithischian dinosaurs were  all herbivorous and originally bipedal. Some remained bipedal, others became secondarily quadrupedal. Some developed bony armor around the body and the end of the tail. Others sported horns on the face, and spike and plates on the back of the skull.

An asteroid collided with Earth some 66 million years ago, creating a vast firestorm enveloping North America that was followed by a drastic worldwide drop in temperature. Related environmental changes brought about a rapid mass extinction of many forms of life across the globe. This included most dinosaur species, but a branch that we call birds survived and continues to evolve today.