Dr. Steven Novella

We don't see them in the low oxygen area.

If they were at the surface, they would have fallen down everywhere when they died.

They would be in high and low oxygen areas.

So the fact that we're seeing them only in the high oxygen locations means that that's where they were living.

So that's a pretty interesting line of evidence.

Yeah, that was interesting, much more interesting than the first one.

All right, the third one, a unique fossil find from China indicates that chordates, the group that includes vertebrates, existed in the late Ediacaran period prior to the Cambrian explosion.

So this is a late Ediacaran, which means that it's, which one of the three assemblages are we talking about?

Ooh, I already forgot.

So there was the Avalon, White Sea, and Nama.

So these are the latest ones, so the Nama assemblages.

This is right before the Cambrian explosion, but still in the Ediacaran period.

And again, it's just a great window into this period.

And what's really good about the China fossil window here is that it's the transition between Ediacaran and Cambrian.

And we don't have a lot of information about that.

So we're seeing this transition, and in this transition, we're starting to see more and more Cambrian fossils.

Now, I said—now, we didn't find a fossil of a chordate.

That's why I said it indicates that— A unique fossil find.

So how could we know that chordates were there if we didn't find a chordate fossil there?

I have no idea.