Three-eyed predator stalked the seas 500 million years ago

The person is Christa Lesté-Lasserre.

A three-eyed animal with wing-like fins used to swim through shallow seas and hunt small sea animals.

The first eyes appeared in the fossil record about 500 million years ago. The arthropods, the group containing insects, arachnids and crustaceans, are the first to have animals with three eyes.

The size of a human hand, S. hirpex had three eyes, two of which were large and protruded from its head.

According to Joseph Moysiuk at the University of Toronto, it probably used its advanced visual system to chase down fast- moving prey.

He says that when we see the evolution of the first predator, we also see the evolution of the complex sensory systems.

Hundreds of well-preserved fossils of S. hirpex were investigated by Moysiuk and his colleagues.

Brains, nerves and reflective materials were all intact in many of the 268 samples. When you split one of these rocks in the field, you can see their eyes shining in the sun. Moysiuk says it was obvious from the beginning that the organisms had three eyes.

The animals had 17 body segments, two pairs of stiff blades along the lower third of its body and spiked claws that could rake prey into its toothed jaws. He says that the animal was a ferocious one.

Moysiuk thinks a large middle eye combined with two other eyes might have been the common form for early animals. The 520-million-year-old Lyrarapax, which was from the same group of early arthropods called radiodonts, had a structure on its forehead that could have been an eye.

Moysiuk says the new finding adds to the strangeness of radiodonts. Radiodonts had a pair of eyes that protruded from their stalks.

The current biology journal has a reference.