Think of a way you could both directly and indirectly observe the types and numbers of birds that live in a forest. also, since no one has ever seen a live dinosaur, how do you think scientists have put together images of what they looked like and what they ate?

Simple answer fossils but the complicated one is Actually they have. And they've drawn them in art, and written about them

Dinosaurs were created on day 6 along with all the other land animals, including Adam and Eve.

Those that think the dinosaurs died out millions of years ago are perhaps unaware of the large amount of evidence indicating that they lived recently alongside man. 
to be honest I think its fossils

They Found fossils and they saw the teeth probably and for example you know how the T-Rex has sharp teeth those teeth are made for ripping meat and the other veggie dinosaurs are made for eating leaves and that's all I have Oh and they found fossils from birds then they did the same thing I told you. That's all I have Thank you for listening. 

Carbon dioxide is the correct answer