New anomalocaridids (Panarthropoda: Radiodonta) from the lower Cambrian Chengjiang Lagerstatte: Biostratigraphic and paleobiogeographic implications

Radiodonts are a morphologically and ecologically diverse clade of stem-group euarthropods that occupied numerous ecological niches in early animal ecosystems. Many Cambrian taxa are considered apex predators, primarily due to the possession of raptorial frontal appendage, though sweep and filter-feeding examples were also prevalent. Four major families have been distinguished including Anomalocarididae, whose elongate appendages consist of a series of podomeres bearing short endites. Studies of anomalocaridids have seen limited investigation in the Chengjiang Lagerstatte (Cambrian Stage 3) of China, despite the deposit being well-known for the diverse radiodont assemblage, and recently the putative anomalocaridid Anomalocaris' saron was reassigned to Tamisiocarididae. Here we present exceptionally preserved specimens of two new anomalocaridid taxa from Chengjiang. Lenisicaris lupata gen. et sp. nov. represents the first valid Chengjiang anomalocaridid taxon, characterized by bearing short endites lacking auxiliary spines on almost all its podomeres. A second taxon, Anomalocaris cf. canadensis Whiteaves, 1892, indicates a broad geographical range for this famous Burgess Shale species. With the help of this new information, we show that the family Anomalocarididae was widespread at low latitudes from Cambrian Stage 4 to the Guzhangian. The biogeographical patterns of anomalocaridids suggest a high dispersal capability in the larval form of anomalocaridids, and possible climatic control on their distribution. Furthermore, the known distribution of anomalocaridids in the well-documented soft-bodied biotas indicates that anomalocaridids were likely adapted to a broad spectrum of environments.

Automated summary

Radiodonts, a diverse clade of stem-group euarthropods, were apex predators in early animal ecosystems, with some exhibiting sweep or filter-feeding behaviors. This study presents two new anomalocaridid taxa from the Chengjiang Lagerstatte, expanding our understanding of their geographical distribution and biogeographical patterns. The well-preserved specimens suggest anomalocaridids had a high dispersal capability and were likely adapted to a broad spectrum of environments.