Henry Gee

which are freshwater deposits.

And they're signs of encrusting mosses, lichens in ponds.

So on land, but not above the surface of the water.

There are in some Cambrian deposits – this was shown to me in the Smithsonian by a lovely fellow called Ellis Yockelson.

He's gone over the Rainbow Bridge since.

There are some Cambrian beach deposits with tracks on that look like motorcycle tyre tracks.

I mean, they're the same width as motorcycle tyre tracks, and they look like motorcycle tyre tracks.

It's as if some –

prehistoric motorcyclist came out of the sea and did wheelies and then went back under the sea so nobody knows what these creatures were maybe some kind of slug like creature and there are thoughts that some of the Ediacaran creatures were maybe intertidal maybe on the beach occasionally but really

for animals and plants in those days to venture above the surface of the sea would be as inimical to life as going into empty space.

So it was a very long time before life came onto land.

That would be another 100, 150 million years after the Cambrian explosion.

I should say, though, that over time...

biodiversity has increased.

Now, that could be because of the pull of the recent, because the more recent the rock, the more of them.

But it does seem to be a real effect.

So just because the Cambrian was really weird and strange, it shouldn't blind us to the weird and strange things that go on around us today, the interactions between creatures.

I mean, I've been learning a lot about parasitism and things.

For example, one of the most successful and species-rich groups of animal today are what's called parasitoid wasps.

They are tiny, tiny, tiny, and we don't notice them.