Young radiodontan arthropods, some of the earliest ocean predators from over 500 million years ago, are now revealed as proficient killers in a recent fossil study led by Jianni Liu from China's Northwest University. While the adult radiodontans, like the famed Anomalocaris, were massive apex predators armed with spiny appendages, the study unveils their tiny offspring as adept hunters.
Arthropods, the “creepy crawly” group that includes spiders and crustaceans, have inspired science fiction monsters with their menacing features. The Radiodonta, an ancient arthropod subgroup, were equipped with large, spiky appendages and circular mouths adorned with tooth-like serrations. Considered giant predators, they reached lengths of over one meter.
Previously, little was known about the juveniles of radiodontans and their feeding habits. The discovery of a remarkably preserved juvenile, Lyrarapax unguispinus, from China's early Cambrian Chengjiang biota, dating back 518 million years, sheds light on these iconic arthropods. Despite being only 18mm long, the specimen displays well-developed anatomy, especially the spiny grasping appendages, resembling a miniaturized adult. This suggests that Lyrarapax unguispinus was a skilled predator at an early stage, akin to modern arthropods like praying mantises and mantis shrimps, highlighting early raptorial feeding habits in arthropod evolution.
Beyond its role in understanding arthropod development, this discovery has broader implications for the Cambrian Explosion, a pivotal evolutionary event over half a billion years ago. Predation is hypothesized as a major driver of this explosion, pressuring animal communities and prompting prey species to adapt or face extinction. The revelation of juvenile radiodontans as predators adds complexity to Cambrian marine food webs, contributing to the ongoing evolutionary arms race during this transformative period.
Source: Science China Press