Henry Gee

One way is to inflate yourself and to make yourself kind of hydrostatically rigid, like an earthworm.

But another way is to clothe your body in armour.

So because of

These things happening at the same time, the bilateral body plan with the mouth and the anus and all that calcium coming into the sea.

And if animals are moving in a particular direction of travel, eyes evolved in the Cambrian.

There's a guy called Andrew Parker who's written and talked about this a lot, about how eyes happened.

So when animals have got eyes and they're moving in one direction, they're usually looking for something.

And what that something is, is food.

So they start to eat each other.

And of course, what with all the calcium, that led to the evolution of teeth and the evolution of armour.

Now, one of the very earliest Cambrian fossils, as opposed to just a burrow, which is what we call a trace fossil, is an animal called Claudina.

It's very, very small, and it looks like a stack of ice cream cones.

And one of the very earliest cloud diners has got a bite crunched out of it.

So even then, back at the very earliest Cambrian, there are signs that animals were taking bites out of each other.

Yes, and it's one of the earliest Cambrian fossils.

And there are plenty of records of trilobites with bites taken out of them.

We'll get to trilobites very quickly.

They're nice hemispherical, semicircular bites.

So whatever they were, they were very tidy eaters.

Well, shall we get to trilobites now?