Predators swimming the seas half a billion years ago may have had significantly less powerful brains than their quarry. That is the theory posited in an analysis released this month in the journal Nature. Examining an intact, fossilized brain discovered last year in Chengjiang (澂江), scientists believe they have identified a new species while also glimpsing how the ancient organism fits into the evolutionary development of brains.
Dubbed Lyrarapax unguispinus by a University of Arizona (UA) research team, the aquatic creature lived roughly 520 million years ago during the Lower Cambrian geological period. Its name means "spiny-clawed lyre-shaped predator" in Latin. It had twin appendages ending in grasping, spiked pinchers set into its head. Mounted behind the claws were two compound eyes.
The nerve center coordinating the eyes and arms of Lyrarapax was quite simple, according to researchers. "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", Nicholas Strausfeld, the lead author of the paper, told website Science 2.0.
Lyrarapax is a member of the phylum Arthropoda, which also contains modern-day insects, arachnids, and crustaceans. Similar, related fossil remains were found nearly one hundred years ago, but paleontologists have never completely agreed as to where the animal fits into biological classifications.
While the discovery in Yunnan does not clear up the evolutionary debate surrounding the development of ancient arthropods, UA researchers are confident that their find has shed new light on the controversy. Strausfeld told reporters:
These grasping appendages are a characteristic feature of this most celebrated Cambrian animal group, whose affinity with living animals has troubled evolutionary scientists for almost a century. The discovery of [a] preserved brain in Lyrarapax resolves specific anatomical [questions].
The area where the fossil was found, referred to by paleontologists as the Chengjiang Lagerstätte, is known for its seemingly endless trove of ancient fossilized sea life, collectively referred to as Chengjiang Fauna. The site is located 50 kilometers southeast of Kunming, near Fuxian Lake. It is considered one of the best places in the world for scientists to conduct research on the Cambrian explosion, a historical epoch characterized by the rapid emergence of the ancestors of almost all animal life present on earth today.
Major fossil finds are common in Yunnan, especially in Chengjiang, and they often offer major clues to how ancient species evolved. Recent discoveries include 'missing links' offering insight into the evolution of faces, the development of central nervous systems and the origins of exoskeletons in the form of 'walking cacti'.
Top image: Discovery
Second image: Nicholas Strausfeld