The eyes, one centimeter in diameter, aremade up of thousands of tiny lenses, just like some insects and crustaceans today. They probably belonged to a large, active, hunting animal, and from the size of the eye, scientists think it could be about 8 inches long. “Compound fossil eyes had been found before, but never so complex. Each one is made up of more than 3,000 small lenses, which made the animal have very sharp vision. In addition, an area of larger lenses, similar to the one that dragonflies have, allowed him to see in dimly lit environments “, highlights Diego García-Bellido, CSIC researcher at the Institute of Geosciences.
The discovery has taken place in some rocks in the town of Emu Bay Shale, on Kangaroo Island. The sediments containing the fossils were deposited shortly after the diversity “explosion” of the Cambrian period, an evolutionary event that marked, between 540 and 520 million years ago, the appearance of almost all current animal groups, such as arthropods, mollusks, echinoderms or chordates.
According to García-Bellido, the work shows that the vision was “extremely complex” since the origin of animal life in the Cambrian. The lenses each produce one pixel of visual resolution, meaning that the animal saw the world with a resolution of more than 3,000 pixels for each eye. Today’s dragonflies have the sharpest eyes known and see the world with almost 30,000 pixels. “The ability to see a predator could be the difference between life and death, or in evolutionary terms, between survival or extinction. The pressure of natural selection must have been very strong to develop and refine the sense of sight. So much so that some scientists suggest that vision was one of the engines that propelled animal radiation during the Cambrian, “the scientist details.
Until now themineralized trilobite eyes, an extinct type of arthropod related to crabs, scorpions or insects, which populated the oceans during the Paleozoic (between 540 and 250 million years ago). “The eyes of the arthropod that we have found are much more elaborate than those of the trilobites with which they lived: they have 3,000 lenses compared to 100 of the trilobites and the diameter of each of them is also larger”, says García-Bellido .
Excavations at this fruitful Australian town, led by the South Australian Museum, began in 2007. Since then, this team of researchers has uncovered more than 5,000 specimens of some 50 different marine species, many still to be described. Among the fossils found, located only one and a half meters deep, stand out several species of trilobites, several types of arthropods not related to any current group, numerous marine worms, algae, sponges and brachiopods, among others.
“We have found that the deeper we excavate, the less deteriorated the rocks are and the better preserved the fossils are. We know that the rocks extend over hundreds of meters, so the potential for discoveries during the next decades is spectacular”, says García-Bellido, who collaborates in the work with scientists from the universities of Adelaide, New England, South Australia and the Natural History Museum in London.
