Creationists believe God made the world in seven days and that evolution is a lie. The Bible does not mention each and every single animal that was created. The Bible mentions that God created the great sea monsters which would probably include the dinosaurs. As for how old the earth and life is the Bible does not say.
So far the seventh day has lasted over 6,000 years.
The Apostle Paul said the seventh day was still in existence in his time.
Then you have the heavens where the birds fly and then there was water on the earth.
Then he separated the waters on the earth into seas and other bodies of water.
The waters in the heavens acted as a barrier to any radiation that would hit the earth.
When the flood came the waters in the heavens were let loose on the earth to flood it.
Once the waters above the heavens were gone then massive amounts of radiation that had built up outside the water canopy fell to the earth.
Critically changing any amounts of radiation on the earth.
So it seems that things are a lot older on the earth then they really are.