Washington

Researchers on Wednesday described fossilized remains unearthed in China showing in fine detail the brain structures of a bizarre group of sea creatures that were the top predators more than half a billion years ago.

The fossils show an animal called Lyrarapax unguispinus, which lived during the Cambrian Period, a pivotal juncture in the history of life on Earth when many major animal groups first appeared. It was a member of a group known as anomalocaridids — primitive relatives of arthropods, which include crustaceans, insects and spiders — that hunted prey with a pair of clawlike grasping appendages in front of the eyes.