A NEW LUOLISHANIID FROM THE EARLY ORDOVICIAN AND THE AUTECOLOGY OF SUSPENSION FEEDING LOBOPODIANS

Lobopodians are a diverse clade of soft-bodied, vermiform marine invertebrates crucial to understanding panarthropod evolution in deep time. We describe a new luolishaniid lobopodian from the early Ordovician Fezouata Shale biota of Morocco with adaptations for suspension feeding. The Fezouata Shale luolishaniid features at least nine relatively robust and annulated limb pairs. The anterior-most limb pairs are elongated with setiform structures emerging from either side of the limb in a chevron pattern. The remaining posterior limb pairs likely end in a terminal claw. The Fezouata Shale lobopodian extends the evolutionary history of luolishaniids, previously only known from early and mid-Cambrian deposits in North America, South China, and South Australia. We also explore the autecological implications of the suspension feeding morphology of all described luolishaniid taxa. Luolishaniids sifted particles and organisms out of the water column that are on the larger end of the micro-planktonic spectrum (20μm - 200μm) and on the smaller end of the meso-plankton spectrum (200μm - 20 mm). We find a statistically significant, positive relationship between luolishaniid maximum body size and setae mesh size, suggesting that larger luolishaniids specialized on meso-plankton while smaller taxa specialized on micro-plankton.