Stegosaurus

Classification: Reptiles, ornithischia
Body length: 9 m
Body weight: 3 t
Epoch: Late Jurassic
Locations: North America
Stegosaurus had 17 broad, upright plates on its back. The purpose of these plates remains unclear. Stegosaurus also had spikes at the end of its flexible tail.
These spikes were up to 1.5 m high, poking out of the sides of the tail, protecting stegosaurus from predators. This dinosaur was a herbivore, feeding only on plants.
Of course, it had to eat lots of low calorie plants to maintain its body and did that using its toothless beak. Its small brain was of a size of a nut.