Final answer:
Ankylosaur evolution took place primarily during the Cretaceous Period, which was a time of peak dinosaur diversity, size, and distribution.
Step-by-step explanation:
The statement is True. Ankylosaur evolution took place primarily during the Cretaceous Period. The Cretaceous Period, which lasted from 145-65 million years ago, was a time when dinosaurs reached their peak in size and distribution. Ankylosaurs, which were armored dinosaurs, were one of the groups that evolved and thrived during this period. The Cretaceous-Tertiary extinction event marked the end of the Cretaceous Period and led to the extinction of the dinosaurs.