Edmontonia

Edmontonia ("lizard from Edmonton [Canada]") is a nodosaur, a kind of ankylosaur without a tail club. It had two large spikes on each shoulder that pointed out to the side. These spikes were a great defense against predators because they were at the same level as the knee and calf muscles of a larger Theropod, or meat-eating dinosaur. If attacked, this slow-moving tank would throw its weight behind these spikes and drive them into the predators legs. This would immediately disable the attacker and allow Edmontonia to walk away.