# Put a tyrannosaur in your tank

The term “fossil fuel” is an evocative phrase, and it got me wondering recently: exactly how many fossils does it take to make our fuel?

Petroleum comes mostly from prehistoric plankton, and coal is basically compressed 500-million-year-old salad. But plants and plankton aren’t any fun. I want to know how many tyrannosaurs it takes to fuel a Honda.

Fortunately, someone has already put in the work for me. One tyrannosaur is roughly equivalent to 460 gallons of gas, enough to drive my ’96 Honda Accord about 13,000 miles.

This is surely a crude estimate (ha!), but close enough for my purposes. If I have my way, we’ll be launching our “Buy a TerraPass, save a dinosaur” campaign any day now.

UPDATE: A commenter points to this study (conducted by an actual scientist, not some joker on Google Answers). The study takes into account the incredible inefficiencies in the process of turning organic matter into oil, which yields an actual conversion rate of 15 tyrannosaurs per single gallon of gas. In other words, it would actually take about 7,000 dinosaurs to keep my Honda going for a year.

### Author Bio

1. - February 22, 2006

Identity to fossil is a petrolium propaganda as more recent unbiased studies suggest that oil is to earth as blood is to humans.

2. - February 22, 2006

If you consider how much of that dino is left after all these years, you might find you need dozens of the beasts to get a single gallon of gas. It took about 100 tons of organic matter (mostly plants – but T. rex too) to create one gallon of gas the old-fashioned way.

3. - February 22, 2006

Huh, thanks for the link. That’s actually the type of calculation I was looking for when I started digging into this question.
Where the original answer goes astray is in assuming that 100% of the dino carbon is converted to oil. In reality, about 0.0093% is turned into oil.
To be fair, the original answer was really calculating a rough equivalence between organic matter and oil rather than trying to determine how much organic matter is actually needed to create oil. As the linked article states, “You can build 1/460th of a tyrannosaur using the carbon in 1 gallon of gasoline.”
But your answer is more accurate, and more eye-opening. I’ve updated the original post.

4. - February 22, 2006

Wow! A study we can actually sink our teeth into. At last we have proof that science can be fun, too. Thanks for the information, and I’m sure that the plant-eating dinosaurs are wishing we had thought of that sooner.

5. - May 1, 2007

The recent exploding tanker truck in Oakland California might be able to add a bit more color to this discussion. A 8,000 gallon tanker truck has about 17 T-Rexes in it. So I guess it takes about 17 T-Rexes to blow up an overpass?

6. - May 2, 2007

Using the more accurate calculation, that tanker truck in Oakland was carrying 120 th-th-thousand T. Rexes.