Ankylosaurus Magniventris

These dinosaurs were the prehistoric tanks of their time. Ankylosaurus magniventris was covered with hard, bony plates that offered superb protection from its most formidable predator—T. rex. Rows of spikes ran along Anklyosaurus's body, and small horns adorned its head to complete an impressive defense array.
Predators would have had to flip the squat, four-legged animal over, exposing its unprotected underbelly, to find a weak spot.
Ankylosaurus's distinctive plates did more than deflect blows—they could also be used as weapons. At the end of the animal's tail, a series of plates were fused together and held aloft by tail vertebra fused together. This clublike tail likely delivered a powerful blow and served as a serious deterrent to would-be predators.
Ankylosaurus had a beak and small teeth, which it used to browse the large quantities of plants necessary to sustain a three- to four-ton body. Ankylosaurus magniventris was the biggest and heaviest of the several ankylosaurid species and grew up to 33 feet (10 meters) long.