Final answer:
Ankylosaurs used their impervious armor for defense, which included bony plates and a tail club, providing effective protection from predators.
Step-by-step explanation:
The defensive strategy of ankylosaurs was based on their impervious armor. These dinosaurs were well known for their distinctive armor that included bony plates and a club-like tail, which they could use to swing at predators. Unlike strategies such as speedy flight, camouflage, or active counterattack, ankylosaurs relied on their armor for protection. This natural armor provided a passive defense mechanism that was incredibly effective against predators of their time.