A new study has revealed a unique kind of ancient lizard that had four eyes. This ancient species of monitor lizard became extinct almost 34 million years ago but has left a quite astonishing thing for the scientists and researchers. The extinct monitor lizard had four eyes and it’s the first time that such a thing is seen in a jawed terrestrial animal, as revealed by the researchers of the latest study.
The name of four-eyed monitor lizard species is Saniwa ensidens. Scientists say that the ancient lizard had a regular pair of eyes along with third eye, called a pineal organ, and a fourth eye, called the parapineal organ. These pineal and parapineal structures were present at the top of the monitor lizard’s head and were light sensitive. They most probably helped the lizard to orient itself and to track seasonal cycles (circadian and annual), as revealed in the study.
It is known that third eyes or pineal organs do exist in many of the lower vertebrates like fishes and frogs and also third eye and fourth eye ( parapineal organ) are found in some of the jawless lampreys as documented earlier. But, this was the first time that scientists were able to discover jawed terrestrial species having four eyes. Scientists were very surprised with the find and they say that this four-eyed ancient monitor lizard will provide information about how such features evolved or how the pineal and parapineal organs evolved in vertebrates. At present, the jawless lamprey is the only creature with a backbone to sport four eyes.
Now, scientists have found out that the Saniwa ensidens monitor lizard that had four-eyes, thus making it the first jawed four-eyed vertebrate. Lead author of the study, Krister Smith, a palaeoanthropologist at the Senckenberg Research Institute in Germany said, “By discovering a four-eyed lizard — in which both pineal and parapineal organs formed an eye on the top of the head — we could confirm that the lizard third eye really is different from the third eye of other jawed vertebrates.” Smith and his team decided to analyze the two museum specimens of S. ensidens and, by doing Computed Tomography Scan, they found out that the ancient monitor lizard species had four-eyes.