In the first chapter of Genesis, verse 21, we read that on Day 5 of creation, God created “every winged fowl after its kind.” This includes birds that flew above the earth (Genesis 1:20). Man and land animals were created on Day 6 of the Creation Week (Genesis 1:24–31). Were there land birds that didn’t fly originally? I would leave open the possibility, but a discussion of this is beyond the scope of this chapter. Most ornithologists say that these birds are secondarily flightless (i.e., they lost the ability to fly). This would be due to variance within kind or to mutational losses since creation. So, the best possibility is that birds were created on Day 5 as flyers, and some have lost this ability, but I wouldn’t be dogmatic.
The extinct aquatic reptiles, such as the plesiosaurs, and the extinct flying reptiles, such as the pterodactyls, are not classified as dinosaurs, and most evolutionists do not believe that they evolved into birds. Thus, for the Bible-believing Christian, both the fact of creation and the order of creation affirm that birds and dinosaurs originated separately.