Question: Was the book of Job written before or after the flood?
Answer: Job was written after the flood. This is the case because everything was destroyed in the flood–which would have included the scrolls. Also, rain, lightening and storms did not occur before the flood (Gen. 2:5-6), but Job encountered such (Job 36:27-30) [Cp., snow and hail (Job 38:22); ice (Job 38:29-30)].
2nd Question: If Job lived after the flood, and if the dinosaurs were destroyed in the flood, then why are the behemoths and the leviathans (which were evidently a dinosaur and a sea creature that lived during the time of the dinosaurs) living at the same time as Job?
Answer: Noah was commanded to take two of every kind (Gen. 7:2). Thus, Noah did include two of every kind of dinosaur (Gen. 7:5). [Note: the sea creatures were not included in the ark–they would survive in the water]. For the reason of conserving space (and for other reasons), Noah could have taken very young dinosaurs, or even eggs. After the flood, creatures were still able to live for long periods (Gen. 11) although the length tapered down through subsequent descendants. Such a long duration of time was needed for dinosaurs to grow so large. Thus, Job lived soon after the flood, during the time when dinosaurs were still possible. [Note: Job himself lived more than 140 years (Job 42:16)].
Gary Henson