Digesting plant fiber is the hardest job. In the eco-system an Ankylosaurus tackle that job, which is why it needed that enormous bulk, gigantic stomach and some divided intestines. And that means you are slow, you are very slow. And you have to feed 12, 15, 18 hours a day. And you’re vulnerable for most of the day and therefore you have to have static armor. 

 

Small and low-slung, this vegetarian can not only survive a T-Rex attack, but sometimes it can even defeat one. Its first line of defense is a tank-like body. 

 

Its primary form of defending itself might be hunkering down onto the ground, letting its armored body protect from the teeth and the claws of the Tyrannosaurus.

 

Ankylosaurus’ specialized armor is designed to be strong and lightweight. Skeletal plates embedded in the skin are aligned in even rows down the neck, back and hips. Spaces between the plates allow this balky creature to move freely. While similar to scales found on today’s crocodiles or alligators, the way these plates are constructed makes them much tougher. 

 

Ankylosaurus has not one, not two, but three layers of armor. And the head is so protected by thick bone that not even an adult female T-Rex could inflict a killing bite.

 

The plates are totally unlike the bones of mammals. They are made of crisscrossing layers of minerals and collagen—fibers made of protein that strengthen bone the way steel rods reinforce concrete. It’s a design used today in bulletproof jackets.