Earth's First Giant Predators Produced "Creepy Crawly" Killer Babies

Until now, virtually nothing was known about the juveniles of radiodontans and their feeding habits. The discovery of an exceptionally-preserved juvenile of a species called Lyrarapax unguispinus from the early Cambrian (518 million-year-old) Chengjiang biota of China has shed new light on this iconic group of fossil arthropods.

At only 18mm in total body length, this almost complete specimen represents the smallest radiodontan ever found. To the surprise of the research team, its anatomy is extraordinarily well developed–especially the spiny grasping appendages–giving it the appearance of a miniaturized adult. This indicates that Lyrarapax unguispinus was a well-equipped predator at an early developmental stage, similar to modern arthropods such as praying mantises, mantis shrimps, and arachnids. This discovery confirms that raptorial feeding habits in juveniles appeared early on in the evolutionary history of arthropods.

This fossil find also has important implications for the rapid evolution of the first animals over half-a-billion years ago – an event referred to colloquially as the Cambrian ‘Explosion’. It is hypothesised that predation was a major driver of this evolutionary event, with predators placing selective pressures o an animal communities, forcing prey species to adapt and evolve or face extinction.The predatory lifestyles of juvenile radiodontans adds further complexity to Cambrian marine food webs by placing additional pressures on small prey during this evolutionary ‘arms race’.Contacts and sources:
Jianni Liu
Science China Press