Bible reference: Genesis 8:15-17
“And God spake unto Noah, saying, “Go forth of the ark, thou, and thy wife, and thy sons, and thy sons’ wives with thee. Bring forth with thee every living thing that is with thee, of all flesh, both of fowl, and of cattle, and of every creeping thing that creepeth upon the earth; that they may breed abundantly in the earth, and be fruitful, and multiply upon the earth.”
Some people worry that dinosaurs would be too big to be on the Ark, but that’s not necessarily true. Dinosaurs came in all sizes: small [chicken-sized], medium [sheep-sized] and, obviously, large. The average dino was the size of a sheep or cow.
Titans [the reeeeally big ones] like Ultrasaurus and Supersaurus were probably just longer-lived [older] examples of their kind. Many animals today, particularly reptiles like lizards and turtles, grow bigger and bigger the older they get. But such giants aren’t typical; they’re special exceptions. In the case of Ultrasaurus and Supersaurus, a lot of scientists think they may have just been really big [and really old!] Brachiosaurs or some other sauropod. Younger animals are much smaller.
In fact, the biggest dinosaur egg found so far is only about the size of a football. The dinosaurs that hatched from those eggs would start off small and then grow bigger over time. We don’t think God sent dino babies to Noah, but it would make sense for God to send younger [and smaller] animals. Younger animals would live longer once they got off the Ark and would be able to have more babies over time and fill the earth, according to God’s will in Genesis 8:15-17.