Let’s read Genesis 6:19, “And of every living thing of all flesh you shall bring TWO of every living sort into the ark, TO KEEP THEM ALIVE WITH YOU; they shall be male and female.” It is clear that God intended to PRESERVE each species of animals for He told Noah to bring them “to keep them alive.”

Now let’s read Genesis 7:1-3, “Then the LORD said to Noah, ‘Come into the ark, you and all your household, because I have seen that you are righteous before Me in this generation. You shall take with you SEVEN EACH OF EVERY CLEAN ANIMAL, a male and a female; TWO EACH OF ANIMALS THAT ARE UNCLEAN, a male and his female; also SEVEN of each bird of the air, male and female, TO KEEP THE SPECIES ALIVE on the face of the earth.” Here we learn that answer to your question, for God had every intention to “keep the species alive” and thus of those animals and birds that were to be sacrificed to Him, Noah was to take SEVEN. We see throughout the sacrificial system in the Old Testament that animals and birds that were offered to God had to be CLEAN (see Leviticus 11:2-23). We see in Genesis 8:20 that Noah obeyed God, for after the flood waters abated “Noah built an altar to the LORD, and took of EVERY CLEAN ANIMAL and of EVERY CLEAN BIRD, and offered burnt offerings on the altar.” God knew that Noah would obey Him (by bring seven of every clean animal and every clean bird), and that his obedience would result in KEEPING THE SPECIES ALIVE. This means that there was not one “species after their kind” (see Genesis 1:20-25) that became extinct in those days.

Some may ask, “Did any of those species die out at some point in time?” Those that ask this often point to the dinosaurs and other species that seem to have become extinct. Some scientists (who are BELIEVERS in God, His creation account, and the true story of Noah and the Ark) believe as many as 70% of mammal families and other species died out later due to climate changes and ecological shifts after leaving the Ark. But this does not change the answer to your question, for God did indeed “keep the species alive” to be used by Noah in his sacrifices to God and it would seem those same species were kept alive for a very long time (as we see in the sacrificial system God ordained for the nation of Israel).  (DO)  (722.5)