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Olivia: Here's a fun connection that people on the internet like to make: plastic is made of oil, and oil is made of dinosaurs, so when you're playing with plastic dinosaur toys you're basically playing with the remains of real dinosaurs. It's fun to think about but it's not that simple.

For one thing, the oil and natural gas that we pump out of the ground are not the chemical leftovers of dinosaurs. Instead, they're made from the ancient remains of a whole bunch of much smaller creatures. The internet might want you to think that oil equals dinosaur corpses, but the fact is that the petroleum we use to make plastics actually comes from ancient ocean floors, where there weren't any dinosaurs.

But those ocean waters did and still do support a mind-bogglingly huge mass of tiny microorganisms, plants, and animals. And not all that biomass gets eaten by bigger creatures. Some of it dies and trickles down through the ocean as so-called marine snow, a sort of perpetual rain of organic matter that falls to the seafloor. If enough of this material builds up faster than it decays, then you wind up with a layer of organic goo at the bottom of the ocean. After a while, the goo can get buried under sand and other sediment and then time, pressure, and heat turn that organic layer into oil and natural gas.

Changes in sea level and the movement of the Earth's crust sometimes force those old ocean floors to the surface, which is why some oil and gas reserves are found on dry land, but others are still underwater like in the Gulf of Mexico.

And there's one more twist to the plastic equals oil equals dinosaur story: not only is oil not made from dinosaurs, but plastic isn't always made from oil. Frequently it's made from natural gas. The main precursor to plastic is a byproduct of petroleum refining called hydrocarbon gas liquids. They're made of relatively light carbon compounds that can be condensed out of natural gas by cooling it. These compounds are used in the chemical reactions that we use to make plastic. And in the United States they're the source of most of the plastic that's made.

So in the end oil and natural gas come from the same place, but it's not some dinosaur graveyard. It's ancient ocean floors, were countless billions of tiny animals, plants, and microorganisms wound up so that your kid could play with their plastic t-rex. Whether you choose to explain that to them is totally up to you. 

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