What if another industrial civilization had existed on Earth tens of millions of years ago, long before humans, but all traces of it have now been lost?

While it may seem like an absurd idea, this thought experiment is the focus of a new scientific paper authored by Adam Frank, an astrophysicist from the University of Rochester, and Gavin Schmidt, director of the NASA Goddard Institute for Space Studies.

They have named the paper “The Silurian Hypothesis” after a fictional race of intelligent, bipedal reptiles from the British sci-fi series Doctor Who—known as the Silurians—that supposedly lived on Earth hundreds of millions of years ago.