Hey four eyes!

Via Smithsonian, a close look at an early vertebrate shows that it had four eyes.

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The earliest known fossil vertebrates, from 518 million years ago, may have viewed the world through four eyes — and one pair of them was the precursor to the pineal gland, according to a study published January 21 in the journal Nature. The findings, which also provide the oldest known evidence of “camera-type” eyes, suggest that these early animals had a more intricate visual system than previously thought. The recovered fossils preserved the creatures’ soft body parts, including a pair of bigger, recognizable eyes on the sides of the head. That’s rare because such tissues often deteriorate before natural processes preserve them.

But peering at the myllokunmingids through a high-powered microscope uncovered something the researchers didn’t expect. “We started by examining the obvious large eyes to understand their anatomy, and it was a complete surprise to find two smaller, fully functional eyes between them.”

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Here is the pineal gland in my 3d form.

It’s under the main part of the brain and right over the cerebellum.

The pineal gland branches off a harp-like structure connecting the two thalami, which are the central tie-point for all the senses. So it’s not surprising to find this extra optic system there.

Our existing eyes feed the thalami in a complicated way, with each side of each eye feeding one thalamus:

These secondary eyes are closer to the nose, and their mechanism closely resembles the structure for the sense of smell. The olfactory bulbs start over the nostrils and send signals back through a similar harp-like structure, the fornix:

The fornix runs directly into the hippocampus, our panoramic map of the familiar world, including smell and sight.