If you have even a passing interest in Earth's deep past, then you're probably aware of the

supercontinent Pangaea. Somewhere around 300 million years ago, just by the nature of how the Earth's

crust works, all of the continents began to assemble into one giant landmass that stretched from pole to pole.

Now this particular arrangement caused some notable things to happen.

The interior of the supercontinent became maybe the biggest desert in Earth's history.

Vast swamps and forests from the earlier carboniferous period died,

and they contributed to our coal deposits, by the way. Less rain and fewer plants means less

weathering, which means less carbon dioxide, naturally pulled from the atmosphere. So, as you

might expect, it got warmer and warmer.

And then around 250 million years ago,

what is now Siberia basically erupted all at once,

filling the air with even more carbon dioxide

and making it even hotter.

And that led directly to the greatest extinction in Earth's history.

The message here, if there is one, is that the Earth has seen some stuff.

For most of the last 500 million years, as long as animals have walked and swam and flown and scuttled around,

it would have been basically unrecognizable to us today.

Scientists are developing ever clearer pictures of these ancient Earths, and, more importantly,

how they got to be that way.

Welcome to the Quanta podcast, where we explore the frontiers of fundamental science and math.

I'm Samir Patel, editor-in-chief of Quantum Magazine.

We've mentioned a few times here our recent special issue on climate science, how we came to

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