Cooperative Shadow Feeding: A Novel Hypothesis for the Feeding Ecology and Evolutionary Adaptations of Long-Necked Plesiosaurs

Plesiosaurs, a diverse group of Mesozoic marine reptiles, have intriguedpaleontologists with their unique morphologies and varied feeding strategies.Recent studies suggest that differences in body size and neck length have significantecological implications. In this paper, we present the cooperative shadow feedinghypothesis, proposing that large-bodied, long-necked plesiosaurs (e.g.,elasmosaurids) engaged in group feeding by casting shadows that attracted schoolsof small fish, which were captured by rapidly extending their necks. This strategywas likely supported by a highly flexible esophagus capable of storing largequantities of prey and by gastroliths that aided in prey processing. In contrast, smallbodied, short-necked forms, such as polycotylids, appear to have been solitaryhunters in deeper waters. We integrate fossil evidence, functional morphology, andcomparisons with modern marine animals to offer a comprehensive view ofplesiosaur feeding ecology and evolution. Our hypothesis not only provides insightsinto the adaptive significance of neck elongation but also suggests potential socialbehaviors in these marine reptiles. We further outline future research directionsincluding biomechanical analyses, taphonomic studies of gastrolith distribution,and paleoenvironmental investigations.