The Artiopoda, exemplified by trilobites, represents a diverse group of euarthropods that thrived during the early Paleozoic. Acanthomeridion serratum, an early diverging artiopodan with a detailed exoskeleton record in the lower Cambrian (Series 2, Stage 3) Chengjiang Lagerstätte, presents challenges in understanding its soft tissues, particularly its post-antennal cephalic appendages. In this study, new micro-computed tomography (micro-CT) analysis reveals that these appendages feature a transversely elongated protopod with teeth-like gnathobasic spines, a delicate endopod without a prominent walking claw and a multisegmented exopod with widely spaced lamellae. Smaller sub-gnathobasic spines alternate with the larger teeth-like gnathobasic spines. The robust protopod, characterized by medially opposed gnathal edges, suggests a feeding function, indicative of a durophagous lifestyle. Phylogenetic analyses place A. serratum as a sister taxon to Zhiwenia, occupying a basal position in the Artiopoda. These findings provide direct evidence of durophagous predation in the Cambrian, likely driving the evolution of biomineralized shells or hard exoskeletons in various metazoan groups.

You do not have access to this content, please speak to your institutional administrator if you feel you should have access.