No, it's not April Fool's.
Researchers have found an ancient monitor lizard with a fourth eye, Yale News reports.
The discovery may hold new clues to the evolution of eyesight in vertebrates.
Yale University paleontonlogist Bhart-Anjan Bhullar is co-author of a study in the journal Current Biology.
“This tells us how easy it is, in terms of evolution, for a complex organ to self-assemble under certain circumstances,” he said. “Eyes are classically conceived of as these remarkably complex structures. In fact, the developing brain is just waiting to make eyes given the right signals.”
Researchers from Yale and the Senckenberg Research Institute in Germany showed that pineal and parapineal eyes, located on the top of the head, were present at the same time in Saniwa ensidens, an extinct monitor lizard that lived nearly 50 million years ago.
The pineal organ is sometimes called the "third eye" when it has a lens and retina, and it exists in some lower vertebrates such as fish and frogs. It was common in primitive vertebrates.
Lead author Krister Smith is a former Yale graduate student who now works at the Seckenberg Research Institute. “By discovering a four-eyed lizard, in which both the pineal and parapineal organs formed an eye on the top of the head, we could show that the lizard third eye really is different from the third eye of other vertebrates,” he said.
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