Stegosaurus

The huge Stegosaurus with its very sharp spiny plates is usually a peaceful animal in the valley of Eodon. Stay out of its way, and and won't have any interest in you. However, should you dare to make it angry, it will show of what matter it is made of, before shredding you to confetti. This is why even the Tyrannosaurus avoids it when possible.

Therefore it is better to not anger it.

Lore
''This beast dates to the late Jurassic era (around 144 million years ago), was some 25 feet long, and weights around four tons. An herbivore, it is notable for the series of spiny plates which protrude from its spine, and for the knot of sharp spikes at the end of its tail - its most formidable weapon. I regret to say that I cannot settle the debate over whether the spiny plates are actually armor or a mere heat - dispersal mechanism; none of these plated beasts has allowed me to get close enough to determine this. However, the natives of the Kurak tribe say that monsters such as the Sharptooth (Tyrannosaurus) circumspectly avoid the spines when attacking the Stegosaurus, which is some evidence that they play a definite defensive role.''

- from "Ultimate Adventures Magazine", Savage Empire