Researchers have found a new member of the group anomalocaridids, among the world’s first predators which dominated marine ecosystems more than 500 million years ago.
The fossils display brain structures similar to those seen in modern arthropods such as crabs, indicating that features of these ancient sea monsters have persisted to the present day.
Anomalocaridids are thought to be closely related to arthropods but this affinity has remained uncertain, partly because it has been difficult to match up features of their claw-like frontal appendages with similar structures in living arthropods.
Nicholas Strausfeld, director of the University of Arizona’s Center for Insect Science, says:
“It turns out the top predator of the Cambrian had a brain that was much less complex than that of some of its possible prey and that looked surprisingly similar to a modern group of rather modest worm-like animals.”
Three near-complete fossils of the creature, called Lyrarapax unquispinus, were found in Cambrian sediments in China.
The traces of brain structures in the specimens provide evidence for segmental compartmentalisation of the head, with connections to the front appendages which resemble those seen in mouth flaps or antennae of present arthropods.
These findings, reported in the journal Nature, suggest that as arthropods evolved, they retained the ancestral connection between the brain and the front appendages.
The Lyrarapax fossil is about 12.5 centimetres long and was found in 2013 by co-author Peiyun Cong near Kunming in the Chinese province of Yunnan.