Scientists have discovered the first Jawed vertebrate having four eyes. A new study finds that about 49 million years ago, a long tailed monitor lizard perceived the world not with two but with four eyes.
The researchers said, the extinct Saniwa Ensidens, a monitor lizard is the first jawed vertebrate who lived 34 million years ago having four eyes. Now, the jawless lamprey is the only known four-eyed creature with a backbone.
The third and fourth eyes are on top of its head, where the lizard’s Pineal and Parapineal organs were located. These pineal and Parapineal organs likely helped it keep tabs on the changing seasons and its own orientation. These aren’t eyes as we know them. They don’t blink and mainly signal the existence of light.
There’s no other lizard like jawed lizard has ever been discovered to have both Pineal and Parapineal eye. While discussing about the creatures the researchers from the Senckenberg research institute and Yale say in their paper “the ancestral pineal organ must have had some latent photoreceptive capability or a structural predisposition to photoreceptivity.”
However, the researchers noted out that this photosensitive Pineal organ is widely found in few lower vertebrates who lay their eggs in water like fishes and frogs. And these photosensitive organs were in lower vertebrates known as ‘third eye’.
But in some vertebrate groups such as mammals and birds the third eye was simply reduced independently and is retained only in lizards among fully land-dwelling vertebrates,”
And it is said by researcher krister smith that the third eye of lizard developed from a different organ, which is called Parapineal, which is well-developed in lampreys.
But the purpose of this fourth eye in addition to pineal eye is hard to say. The organs aren’t a working duo like eyes typically function, and they acts independently.
It is found that lizards lost their third eye in the evolutionary part and the researchers are figuring out the reason behind this.