Henry Gee

And they had eyes, but more than that, they had four eyes.

They had two pairs of eyes.

In addition to the regular pair of eyes, they had another accessory pair next to them of smaller eyes.

So Milo Kunmingi, the earliest vertebrates, had four eyes.

What happened to these other two?

They eventually went inside the head and became the pineal gland, which is still... You know, we have pineal glands in the middle of our heads, but they're connected by nerves to the eyes and the optical centres of the brain.

And these are the glands that help us regulate our biorhythms.

They produce melatonin and they keep our day and night cycle.

And...

they they are what goes out of sync when you fly a long way and get jet lag so but originally these were eyes with lenses and retinas and there were four of them in the earliest fishes so these were the earliest vertebrates from from chengchang they weren't armored at all there had been

an idea that there were armored fishes in the Cambrian, but that has been debunked.

The problem with the armored fishes in the Cambrian was they're just shown from fragments, tiny fragments.

As if you took an armored fish and you stomped on it and rolled over it with a steamroller and scattered all the bits, and then you found one bit.

But of course, these tiny fragments of armour you could study under a microscope.

The problem is they're indistinguishable from arthropod skeletons.

So these fragments that had been attributed to fossil fish were probably some kind of arthropod.

So the fish that we see in the Cambrian are...

unarmoured.

It was only later in the Ordovician that they became armoured.

Yeah, the origin of vertebrates has been a really big problem for a long time because vertebrates are so different from invertebrates in many, many ways.