You know, I have this sort of personal philosophy: God used science in his creation of the universe and the earth took place over billions of years, and the dinosaurs were as such created by him through biological evolution. Instead of trying to fit an entire semesters' course of biology, history, archeology, and so forth into a single book, it was probably easier to describe his work to Mankind in terms they could understand. Its the same thing when we try and explain complex ideas or situations to a child. We leave out most details and let them know in simple language of what's going on.
Do you think a simple biblical era Man will understand complex mathematical equations, or large scale governing dynamics of planetary rotations and quantum mechanics? Its easier to just tell to the scripture writer "Behold, and I said, let there be light" as opposed to...
Science can be thought of as a way of interpreting God's revelation found in nature. If Dinosaurs never existed during the age of Mankind, then it would seem to be logical that God wouldn't mention much or anything of them. Afterall, while he did create them at one point, they were not life that was around at the time of the biblical era in any recognizable form.
I know this will probably be instantly contested by people here, but it makes a lot more sense to me then "God planted them for the lulz".
--edit--
Leknaat beat me, and summarized it in a shorter way to boot
Jam it back in, in the dark.
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