Paleontology is a relatively new science. infact the concept of 'dinosaurs' only surfaced in its present form less than 180 years ago. Prior to that anyone who found a large fossilized bone assumed it came from an elephant, dragon or giant. It wasnt until 1841 that an english scientist Richard Owens suggested that the group of 'newly discovered' animals be called dinosaurs. Therefore we shouldnt expect to see dinosaurs in the bible, but we should expect to see descriptions of 'dragons' and other large creatures. Infact we do!!
The word 'dragon' is used throughout the old testement - it translates in many current day bibles as sea or land monsters. Infact in the book of Job, the author describes the great land creatures.
The bible is clear, sea creatures were created by God on day 5 and land creatures by God on day 6. These included dinosaurs, which co-existed with man until they died off for various reasons, including the worldwide flood of Noah.
And just incase you wondered, the seven days is not the same timescale as our 7 days. Our calander did not exist then.