I was reading this thread from six years ago by M.J.
It's a great topic and well worth a read. The existence of dinosaurs has long vexed the WTS, I believe. For an organization that believes everything can be explained by the bible, they are curiously silent on this topic.
On page 2 of the thead, Botzwana and Simon 17 both said that they have heard JWs say that dinosaurs were created so that man could have oil. This was a popular belief of JWs when I was growing up. I imagine this is an example of the kind of reasoning that would lead JW's to that conclusion:
Jehovah created everything, including dinosaurs.
There must be some reason for them, because everything has a reason or purpose.
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Dinosaurs became extinct-probably due to Noah's flood.
Dinosaurs were big and prolific, thus dinosaurs would have created a great deal of decayed matter.
Oil comes from decaying organic matter.
Oil must come from dinosaurs.
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We use automobiles to preach the good news.
Automobiles consume fossil-fuel.
Jehovah must have created the dinosaurs so that we can have gasoline to preach!
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This fallacious reasoning was unwittingly helped along, no doubt, by the Sinclair Oil Company, which had gasoline stations throughout much of the US in the mid-twentieth century. Sinclair's logo included a large, green brontosaurus. Even a cursory investigation into the history of the Sinclair logo indicates that the oil company, staffed by geologists and geophysicists, did not believe that petroleum came primarily from dead dinosaurs. They were simply drawing a connection between the formation of petroleum and the age of dinosaurs. They knew that the bulk of all hydrocarbons were formed over many millions of years mostly from decaying plankton and algae in lakes and seas. But it's a great example of how JW urban legends start, and how gullible Witnesses can be.