think of it this way, one day isn't actually a day, dinosaurs were probably around starting from the 5th "day". and later in the old testament they probably died off, most of the things in the bible happen in the same place, but there is still much more land on earth, some bibles have maps and if you look at it, you can actually match that map to the continent Pangea that scientists said was real, the dinosaurs probably lived away from civilization. but its God were talking about so anything is possible