Final answer:
The claim that a cold-blooded Brachiosaurus might have taken more than a century to reach adult size is false. Dinosaurs, including Brachiosaurus, reached maturity much faster, and the warm climate of the Cretaceous Period would have facilitated their growth.
Step-by-step explanation:
The statement that a cold-blooded Brachiosaurus might have taken more than one century to reach adult size is false. During the Cretaceous Period, which lasted from 145 to 65 million years ago, dinosaurs indeed reached their peak in size and distribution. However, the growth rate of dinosaurs would not have allowed for a century-long growth period to adulthood. Dinosaurs like Brachiosaurus, which were sauropods, likely grew quickly to adult size like many other dinosaurs. As reptiles, their growth rates could be affected by environmental factors, but they did not take a century to reach maturity. The climate during the Cretaceous was warm, and even the poles lacked ice, which would have helped ensure a relatively constant and suitable environment for the growth of large dinosaurs.