The Jurassic Period started 201 million years ago, and lasted until 145 million years ago. Dinosaurs thrived in this era, and are known for their towering size. Here's a list of prolific dinosaurs during the Jurassic Period: The Brachiosaurus was a huge plant-eating dinosaur that lived in prehistoric North America. The Stegosaurus was another large plant-eating dinosaur from the Jurassic Era.