New observation on Corynetis from the early Cambrian Guanshan Biota reflect burrowing life.

Abstract

Priapulids demonstrated greater disparity among anatomical morphology and played a pivotal role in early Cambrian marine ecosystems. This disparity appeared in ornamented cuticle and showed adaptability to diverse ecological patterns, which lack detailed investigations. Our study focuses on Corynetis from the Guanshan Biota, a poorly understood priapulid taxon with spiny ornamentations, including two species: Corynetis brevis and Corynetis fortis. Significantly, Corynetis brevis is documented within the Guanshan Biota for the first time. A new discovery is the identification of circumoral crown, a novel scalids that encircles the mouth and comprises two rows of eight scalids each, suggesting a sensory capability. In addition, comparative analysis of the terminal trunk spines reveals subtle yet important morphological differences between the two species. This distinction likely reflects differing anchoring strategies, terminal trunk specialization in Corynetis brevis versus whole trunk utilization in Corynetis fortis, which form single-anchor modes and likely facilitate rapid withdrawal in burrow. As well as the specialized coronal spines that grow faster than other structures, its sensory function can enhance predation. Ultimately, palaeoecological reconstruction suggests that Corynetis was a solitary organism with carnivorous habits, predominantly dwelling within a burrow.