Preliminary Study on a New Aysheaia-like Lobopodian from the Cambrian Sirius Passet Lagerstatteä

The origin of frontal appendages represents a critical milestone in the cephalization and early evolution of stem-group euarthropods. However, long-legged stem-group lobopodians with frontal appendages have not been reported apart from Aysheaia from the Miaolingian Burgess Shale. Here, we present preliminary observations of a new, exceptionally preserved lobopodian (~10 cm in length) from the early Cambrian Sirius Passet Lagerstätte. The new animal exhibits notable morphological affinities with the Burgess Shale lobopodian Aysheaia, sharing features such as a terminal mouth, a pair of frontal appendages, and distal spines on the annulated walking legs. The trunk bears nine pairs of walking legs equipped with a pair of terminal claws. Notably, the head region features a pair of specialized frontal appendages bearing spine-like structures and a single terminal claw. Features shown in the frontal appendages may indicate a raptorial function, and further imply that this taxon might have been a macrophagous predator, utilizing its anterior appendages to grasp prey before swallowing. Representing a possible basal position among lobopodians with differentiated frontal appendages, this new fossil could provide important clues regarding the emergence of active predatory ecology in early Cambrian marine ecosystems.