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Does oil come from dinosaurs?

There is a fairly widely held belief that oil comes from dinosaurs, but are fossil fuels really the remnants of these prehistoric beasts? Is oil being made from dinosaurs an idea with any basis in scientific fact, or is it simply a work wholly born of fiction?

Fossil fuel

The starting point could well be the term “fossil fuels”, that is used to describe coal, oil and natural gas. We all know that dinosaurs left behind fossils, and the fact that they did so explains why we even know that they ever existed.

On the South Coast of England, there’s even a “Jurassic coast” that runs through the bottom edge of Dorset and Devon, stretching for almost 100 miles. The area is so called because it contains rocks that record almost the entire Mesozoic Era, which took place between 250 and 65 million years ago. These rocks are spread out along the length of the Dorset and Devon coastline that make up the Jurassic Coast. The area is therefore a permanent record of three significant geological eras known as the Triassic, Cretaceous and, of course, Jurassic eras.

Fossil hunting is, understandably, a very popular pastime among those visiting the Jurassic coast. Residents and day-trippers alike scour the beaches, hoping to take home their very own ammonite as a prize. If they do discover a rock with the imprint of an ancient lifeform on it, then it is a thrilling moment indeed for both young or old.

It’s easy to see where the idea that oil comes from dinosaurs came from. If people know that you can find dinosaur fossils in rock, and they also know about “fossil fuels”, then it’s simple to understand why this connection – a misconception, in this case – has been made.

Oil is not made from dinosaurs

The idea that fossil fuels – oil, coal and natural gas – are made from dinosaur remains is not fact but fiction. This is despite the fact that one oil company, Sinclair, uses a dinosaur on its logo.

What is fact, however, is that fossil fuels began many millions of years ago, when dinosaurs were still inhabiting planet Earth. What’s more, the principle of fossil fuels is basically extremely simple. Within oil, natural gas and coal are atoms, and between these are chemical bonds. These bonds contain stored energy. These bonds are broken when the fuels are burned, which releases the energy – and the original source of this energy was the sun. Many millions of years ago, living plants photosynthesised and created stores of solar energy within them. Some of these plants died and decomposed, while others were eaten by animals. Their consumption of the plants simply moved the energy up the food chain.

Some kinds of flora or fauna can eventually become fossil fuels. However, the perfect conditions must exist – and these must include a very low oxygen environment. It also takes such a very long time.

How coal is made

Coal that is used today, and perhaps even more widely in past decades, began 300 million years previously, when dinosaurs roamed the Earth. However not even coal contains dinosaur matter. Rather, wetland plants died, and their remains sunk to the bed of the swamp or bog. Over time, the remains decomposed and gradually became peat. Later, when the bogs and swamps dried out, other matter settled over the surface of the peat. Pressure, heat and, again, time, caused the peat to become coal. This is why miners must enter and dig deep into the earth to extract coal.

How oil and natural gas are made

Oil and natural gas can trace back their origins to a process that started within the ocean. Small sea organisms such as algae and plankton died and sank to the sea bed. Over time, dirt and debris settled over the decaying remains. A series of chemical reactions meant that two substances were eventually formed. These are a black tar called bitumen, and a waxy substance called kerogen.

As the kerogen became buried ever-deeper, both the temperature and the pressure it was subjected to increased. The kerogen could then become what we now know as crude oil. Even higher temperatures, meanwhile, could lead to the production of natural gas.

The molecular structure of the oil and natural gas is not as dense as rock or water. They therefore rise upward, through porous rock, until they reach a point when they become trapped. This occurs when something above them is even more dense than they. After this point is reached, the only option is for the substance to simply accumulate. This is how oil reservoirs are formed, and they will stay in place until humans drill down to access and extract them.

Fact versus fiction

The idea that oil comes from dinosaurs is therefore fiction. Rather than being made from dinosaur remains, oil was formed from matter left behind by dead marine life. This all took place millions of years ago, and some of this occurred even before dinosaurs lived. It also continued to take place while they roamed around the planet. The seabed was where oil formation happened, so because dinosaurs lived on land, they were not at all involved in the making of those oil reservoirs we draw upon today.

Only the tiniest organisms later become oil or natural gas. When the dead sea life decomposed, most of the nitrogen, oxygen, sulphur and phosphorus and sulphur were removed. What remained was a muddy sludge composed chiefly of hydrogen and carbon.

Over a vast period of time the sediment became deeply buried under sand and silt, and then heat and pressure caused crude oil to form in reservoirs, and natural gas to be produced when temperatures were extremely elevated.

The pressure and heat that were present could determine which type of oil or gas were formed. Lower temperatures produced thicker substances, while higher temperatures resulted in lighter types of oil. Even more heat could result in natural gas. If temperatures exceeded 260°C, any organic matter would be destroyed, so neither natural gas nor oil were made.

1 thought on “Does oil come from dinosaurs?

  1. […] discussed this in a recent blog. In fact dinosaurs roamed the earth, not the sea – and the oil is extracted via oil rigs […]

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