Euoplocephalus

It has been said that the herbivores and carnivores forced each other to evolve in a rapidly escalating battle of armor vs. firepower. If this is the case, and it seems very likely it is, then a very successful biological armored vehicle was Euoplocephalus.

Pronounced you-op-luh-SEF-uh-lus the name means "well protected head. This tank-like creature was from the late Cretaceous and is in the Ankylosaur family. It was believed to weigh in the 3 to 5 ton range and averaged 20 feet in length and maybe 8 or 9 feet in width.

What is unusual is that this heavily armored dinosaur was very likely totally immune to the attack of the large carnivores like T rex. It's strategy may well have been to first try and use it's bony and spiked tail to dissuade its attacker and then if that didn't work to simply hunker down in the sand or earth, protect its head and just out-wait its adversary. As a side note there have been T rex leg bones found that were fractured in just the manner that Euop would have done if it connected.