Ankylosaurus

The Ankylosaurus is a three-part fossil in the introduced in  that appears in all subsequent games to date.

In
"Huzzah, I say! HUZZAH! Such joy! Such delight! If I may be so bold, allow me to expound briefly upon the ankylosaur... This marvelous herbivore was covered in spikes from head to back, eh wot? I challenge you to find a more perfectly protected body. You shan't succeed! Not only that, but this great beast could also swing its hammerlike tail! Hoo, this allowed it to attack as well as defend. With an attack like that... Why, any carnivore would likely think twice about snacking on this fellow! Ah! Forgive my babbling. It's that tail, you see... One can't help but rave!"

In
"Ankylosaurus was armored on its head and back with savage-looking spikes. It's rather brilliant that it had such formidable defenses despite the fact that it was an herbivore. These fellows could also hit predators with their hammer-shaped tails! They were a right fright when angered. Much like the president of a company or something..."

In
"The ankylosaurus is famous for the distinctive armor that covered its body from head to toe. This armor consisted of large bone knobs and plates covered in a thick, leathery skin. When threatened by the carnivorous dinosaurs, it would swing its club-like tail to protect itself."

Real-world information
Ankylosaurus was a large dinosaur that existed during the late Cretaceous period. It was a herbivore and the largest known ankylosaurine (characterized by bony armor and a tail club), reaching 6-8 meters (20-26 ft.) in length and weighing around 5 tons.