Fossil Fuels

The other day I had a conversation with a retired schoolteacher who said that she didn't understand how oil and coal were fossil fuels because "there weren't that many dinosaurs." I tried to explain that any organic matter (plants, etc.) was part of the fossil fuel equation. She countered with the taxonomy of "animal, vegetable, mineral", so if coal is a mineral, it can't have been a vegetable. It's Lent, so I decided to give up.