Science, Tech, Math › Science Oil Comes from Dinosaurs - Fact or Fiction? Chemical Composition and Origin of Petroleum Share Flipboard Email Print The organisms that formed petroleum lived long before the dinosaurs walked the earth. Mark Garlick, Getty Images Science Chemistry Biochemistry Basics Chemical Laws Molecules Periodic Table Projects & Experiments Scientific Method Physical Chemistry Medical Chemistry Chemistry In Everyday Life Famous Chemists Activities for Kids Abbreviations & Acronyms Biology Physics Geology Astronomy Weather & Climate By Anne Marie Helmenstine, Ph.D. Chemistry Expert Ph.D., Biomedical Sciences, University of Tennessee at Knoxville B.A., Physics and Mathematics, Hastings College Dr. Helmenstine holds a Ph.D. in biomedical sciences and is a science writer, educator, and consultant. She has taught science courses at the high school, college, and graduate levels. our editorial process Facebook Facebook Twitter Twitter Anne Marie Helmenstine, Ph.D. Updated March 02, 2019 The notion that petroleum or crude oil comes from dinosaurs is fiction. Surprised? Oil formed from the remains of marine plants and animals that lived millions of years ago, even before the dinosaurs. The tiny organisms fell to the bottom of the sea. Bacterial decomposition of the plants and animals removed most of the oxygen, nitrogen, phosphorus and sulfur from the matter, leaving behind a sludge made up mainly of carbon and hydrogen. As the oxygen was removed from the detritus, decomposition slowed. Over time the remains became covered by layers upon layers of sand and silt. As the depth of the sediment reached or exceeded 10,000 feet, pressure and heat changed the remaining compounds into the hydrocarbons and other organic compounds that form crude oil and natural gas. The type of petroleum formed by the plankton layer depended largely on how much pressure and heat were applied. Low temperatures (caused by lower pressure) resulted in a thick material, such as asphalt. Higher temperatures produced a lighter petroleum. Ongoing heat could produce gas, though if the temperature exceeded 500°F, the organic matter was destroyed and neither oil nor gas was produced. Comments Readers shared opinions on the topics: (1) Victor Ross says: I was told as a child that oil came from the dinosaurs. I didn’t believe back then. But according to your answer, I’d like to know how the oil in the tar sands of Canada was formed, and the oil in the shale in the USA was formed. Both are above ground, or at least shallow buried. (2) Lyle says: Its always been hard for me to believe that such large deposits of oil located so deep below the surface of the earth could come from fossil remains, whether from dinosaurs or plankton. Looks like some scientists are also skeptical. (3) Rob D says: I must have been lucky in my educational journey through life, its the first time I’ve heard this silly misconception (not a perception). Oil and gas below landlocked regions? No problem, you just need to be aware of Plate Tectonics and other geological processes; there are fossils of sea creatures near the summit of Everest! Of course some people choose mysticism and superstition to explain these things, which is where the dinosaurs and oil connection possibly originates – from those who lump all (what to them are) “scientific mysteries” together.Regarding the oil Without fossils; just reading the title of the research paper sheds some light as to where this is going: “Methane-derived hydrocarbons produced under upper-mantle conditions”. So these guys say no need for fossils to produce oil (i.e. not a fossil fuel), but where does the methane come from? Yes, I’ll give it a read but I’m not hopeful they have overturned established theory just yet (always remember how the media reports science – they love the controversial and the sensational). (4) Mark Petersheim says: I want to know, is there any positive effect of crude oil on the environment? Not long ago we discovered that microbes lived in extreme temperatures near thermal vents on the ocean floor, we never thought this was possible. There must be something that eats crude oil. Some other species must benefit from this bi-product of nature other than humans. Anybody out there have data to support this? (5) winoceros says: Certain bacteria digest crude oil. It leaks into the oceans naturally all the time, is “eaten” or broken down, and used as energy by the bacteria. If it’s got carbon in it, something will figure out how to eat it. (6) Ed Smithe says: How is it then that we have found petroleum on Titan (Saturn’s moon), which, as far as we know, has never hosted life? This theory is at best flawed, and at worst, invalid. Obviously there are processes at work that don’t require dinosaurs, or plankton, or other living things to create hydrocarbons. (7) Chrystal says: Couldn’t it then be assumed that dinos that fell into the sea or lived in the sea became petroleum in the same manner? (8) Andre says: That was my thought too. That dinosaurs could also be the animals that became oil. I’m sure some oil existed before dinosaurs but if the theory is true, how could they not be a contributor at all? (9) Andre says: Andre: If oil came from dinosaurs, you would find some form of it around dinosaur fossils. This has never really been the case, and even if it were present it would be in isolated pockets so tiny that recovery would be a waste of time. Diatoms and other life that fell to the ocean floor over a period of millions of years are the only things capable of leaving volumes large enough to extract. (10) J. Allen says: What if we wake up one day and find out that the oil we have been pulling from out of the Earth is the glue that is holding the planet together? (11) Matt says: @ Victor Ross…Shale is a deep marine sediment. Usually formed in the abyssal plains of the ocean. The only reason it is shallow on land is because of uplift and erosion through millions of years. Tar sands are shallow because its an asphaltic type of hydrocarbon formed in low temperatures, low pressures, and shallow depths. Here in Texas or Oklahoma you can find oil just hundreds of feet below the surface. Sometimes this happens due to microfractures or faults that oil can flow through. Just like water, oil flows from a high to low gradient or is forced up through high formation pressures. Scientists should not be skeptical because oil is a hydrocarbon. It has to come from either living organisms or plant life. It can’t form from anything else. Pressures and temperatures are the deciding factor of what type of oil is formed, if any at all. low temp + low pressure = asphalt….mod temp + mod press =oil…high temp + high pressure = gas, extreme pressures and temperatures will completely breakdown the hydrocarbon chains to were it is completely burned off. Methane is the last chain hydrocarbon before it becomes nothing. (12) Ron says: I don’t know or really care how the oil and gas got there, but what concerns me is that it is there to act as a cushion between the tectonic plates. Removing it may lead to some very violent earthquakes in coming years. (13) Luis says: Back in the 80′s I was told in elementary school (in MX) that oil comes form dinos. My first question was “well, how many dinosaurs we need to make an oil deposit of millions of barrels?” Obviously I never believed that hypothesis. (14) Jeff C says: The theory of “fossil fuel” is just a theory. There is no evidence of crude oil/gases beingcreated by decaying creatures or plants. What do we really know? We do know thatTitan has carbon based oil. This has been proven. We do know that the universe hasmultitudes of gases which are carbon based in the absence of plants/animals. The theory of fossil fuel is yet another erroneous conclusion that the lemmings blindly adhere to with little or no objective analysis. (15) The Truth says: Oil doesn’t come from living things. All you need to do is study the Russian research since the 1950′s to figure that out. It is an artificial theory designed to apply the label of limited resource to keep the price artificially high. Dig past the fossil layer? Oil. Dig into bed rock? Oil.Dig under the ocean floor? Oil. Dig in shale? Oil. Time to wake up to reality. (16) Danny V says: Wrong! Oil does not come from any living thing. This is a lie that was formed during a convention in Geneva in the late 1800's in order to have us feel that it is very limited and running out. Science has bought into it, just as they have "macro-evolution." (17) danny says: Jeff, you are absolutely right, especially in your use of the term “lemmings.” (18) lore says: Like other “created” things (e.g., grass, trees) there are things uniquely “themselves.” Only God can make a tree. Likely the lubricant of oil on the tectonic plates was placed there like we lubricate an engine to prevent explosive friction. I have personally spoken with two geologists who agree that oil drilling has definitely changed the earth's composition causing a sharp rise in earthquakes. When one looks at the process of drilling and fracking it's easy to see why earthquakes and tsunamis are a major threat to the earth's ruination from man's interference. (19) youip says: The oceans died. Natural CO2. Hyper volcanic activity over long periods of time no ice caps. A greenhouse planet full of plant and reptile life. Wonderful conditions for plants. Gargantuan leaves. Apparently plant life was not enough to keep carbon in check in time despite its prosperity. This, unlike our dilemma was a long time coming not a span of a few centuries. Low O2 oceans gave rise to plankton. Whole thing was as a swamp layer from all the death. They sucked out what remained, blocked out life and the vast majority of the oceans, and everything in it died and became acidic. Heat keeps rising, oceans evaporate faster, very acidic rain hits the land and shore lines and soil erosion/land slides/typhoons becomes common. Throw into the mix still active plates and a lot of land life plant and animal found its way to the oceans grave. Oil is a wonderful carbon. All life reduces to carbon. So oil comes from death concentrate and loads of it. Its how the Earth stored its carbon excess as it and its possibly our fate to return to it for dredging it up and releasing it. It’s bittersweet, but its beautifully balanced. Understood or accepted that makes no difference. It does what it does and works how it works. Powerlessness and ignorance are hard truths to swallow yet it goes on despite any preference. Tough luck. (20) Robin says: Let's suppose the oil we remove is the buffer that keeps the planet from heating up. Say oil in a pan with heat on it can absorb more heat then the water that displaces the oil because water boils and turns to vapor. Water is put in reservoirs beneath the ground in order for the oil to be pumped out, leaving trillions of gallons of water where there was once oil. Now think what will happen once the oil is gone and the water is put into those areas, Do you think we might get a planet that is heating up? And a planet that heats up cannot be good hence global warming. Experiment for you home dwellers. Put water in a pan and then put oil. What tends to develops when both are set to 220 degrees? Now the core is over 5000 degrees. What is buffering us from that. Water? Dream on. (21) bob says: I think it is funny that educated adults can be so stubborn that they will not let go of all the fairy tales and myths they were told as children. Even this new ‘theory’ is just an interim step for baby boomers and older generations who got tricked by clever marketing and are struggling to accept the facts. The facts are that coal, natural gas, oil, and diamonds all come from the same geological processes – carbon under heat and pressure. Varying the heat and pressure produces the different end-products. The only reason they wanted you to believe oil was decomposed dinosaurs (and now, decomposing plankton) is because oil was way too plentiful to justify rising prices. Demand and scarcity are both factors in pricing. A compound that practically gushes up when you poke a hole in the ground would not cost that much. A compound that simple folks believe took millions of years to create from a now-extinct life-form costs more. Don’t even start to investigate how DeBeers creates artificial scarcity for diamonds by paying millions of dollars a year to take cartloads of diamonds out of the market, to maintain prices at scarcity levels. Then they sell this myth of hard-to-extract, rare diamond, even though there is a beach in south Africa where the sand is like 75% diamonds, and the south African government will shoot you for trespassing. (22) Lore says: To youip: I'm fascinated how you present your dogma here based on the fact that all life is carbon. That is no proof of your theory. There is no proof that the ocean ever “died” (though as a living organism it is certainly dynamic and adapting, not always well, to surrounding changes) and maybe the myth of changes through your described deaths producing oil are just too far fetched and as Bob said, that reasoning looks suspiciously like fake supply and demand stuff. I will add evolutionary desperation to attempt to rule out and sentient reason for oil being created (As Bob and Robin both eluded to, not meaning to put words in their mouths, but that oil has a purpose). Robin: right on. Bob: thank you.