Freaky Ancient Lizard Had Four ‘Eyes'

An ancient species of monitor lizard that went extinct some 34 million years ago had four eyes, according to new research. It’s the first time that scientists have ever seen such a thing in a jawed terrestrial animal—an observation that’s filling a gap in our understanding of how these features evolved. In addition to its regular pair of eyes, the extinct monitor lizard Saniwa ensidens featured a third eye, a structure known as the pineal organ, and a fourth eye, the parapineal organ. These light-sensitive structures sat atop the creature’s head, likely helping the lizard to orient itself and to track seasonal cycles, according to new research published today in Current Biology. So-called “third eyes” are known to exist in a wide number of lower vertebrates, such as fishes and frogs, while third and fourth eyes have also been documented in jawless lampreys. But this is the first time that both the photosensitive pineal and parapineal organs have ever been seen in a jawed terrestrial animal...MORE