These small primates have the largest eyes of any mammal, relative to their body size. Each eye is about the same volume as the animal's brain. Trilobites lived between 521 and 252 million years ago.

They need to do what Nilsson did with the box jellyfish: understand how animals use their eyes. Around 540 million years ago, the ancestors of most modern animal groups suddenly appeared on the ...

Trilobites became the first active predators, able to seek out and chase down prey like no animal before. Unsurprisingly, their victims counter-evolved. Just a few million years later, eyes were ...