[Strategerist]

We can only assume that they slowly “combusted”, turned to water vapor and CO2 and left behind but traces of their former selves over 100s and 1000s of years; how much of the plant growth was supposed to have been trapped underground to be compressed into crude over time?

There are no trees, land plants, or dinosaurs in crude oil, and there's never been a theory to that effect.

Oil comes from ancient dead microscopic plankton (algae and diatoms) that lived in shallow seas.

[El Sordo]

So I am thinking coal then, and not oil.

[Old Professer]

Cool, then all that water must have receded or all the oil would now be found under the oceans; can we do that again?

[scan59]

There are no trees, land plants, or dinosaurs in crude oil, and there's never been a theory to that effect.

Oil comes from ancient dead microscopic plankton (algae and diatoms) that lived in shallow seas.

Actually, during elementary and jr high school back in the 60's and 70's, we were taught that it came from dead dinosaurs, trees, and other plant life. Guess our teachers were taught wrong themselves. (Government conspiracy? You decide... Just kidding.)

[Nowhere Man]

There are no trees, land plants, or dinosaurs in crude oil, and there's never been a theory to that effect.

Oil comes from ancient dead microscopic plankton (algae and diatoms) that lived in shallow seas.

Well, I know I took some bio waste as an experiment and it seemed to decay into an oil-like morass. I say it is possible that past life has become fossil fuels but I do believe that is not the only way fossil fuels can form. I've heard of your theory as well and I believe that is it quite possible. IIRC, there was a Soviet scientist back in the 1970's who claimed that oil production can be a natural planetary process as well. There are stories of play out oil fields becoming viable again and even here in the Pittsburgh area, there is talk of bringing some old oil wells online again. I think there could be multiple ways and sources at play here.