Final answer:
Ankylosauria includes two dinosaur families, Nodosauridae and Ankylosauridae, which were heavily armored and lived during the Mesozoic era, specifically in the Late Cretaceous period.
Step-by-step explanation:
Ankylosauria is composed of two families: Nodosauridae and Ankylosauridae. Ankylosauria is a clade of armored dinosaurs that lived during the Mesozoic era. These dinosaurs are part of the larger group known as Archosaurs, which includes all dinosaurs, as well as modern crocodiles, alligators, and birds. Specifically, Ankylosauria falls within the Ornithischia, the "bird-hipped" dinosaurs, noted for a pelvic structure superficially similar to birds. However, the birds we see today evolved from the Saurischia, which had a "lizard-hipped" configuration.
The Ankylosauridae, on the other hand, are famous for their massive tail clubs and were similarly armored. Both of these dinosaur families used their armor as a defense mechanism against predators during their time in the Late Cretaceous period, about 145.5 to 65.6 million years ago. The ankylosaurs' distinct features such as their armor and tail clubs set them apart from other dinosaur species and greatly contributed to their survival and evolution.