Vertebrate Palaeoecology of the Pisco Formation (Miocene, Peru): Glimpses into the Ancient Humboldt Current Ecosystem

The northward-flowing Humboldt Current hosts perpetually high levels of productivity along the western coast South America. Here, we aim to elucidate deep-time history this globally important ecosystem based on a detailed palaeoecological analysis exceptionally preserved middle–upper Miocene vertebrate assemblages Pisco Formation East Basin, southern Peru. We summarise observations hundreds fossil whales, dolphins, seals, seabirds, turtles, crocodiles, sharks, rays, and bony fishes reconstruct ecological relationships in wake Middle Climatic Optimum, marked cooling that followed it. lowermost, middle sequence (P0) its assemblage testify warm, semi-enclosed, near-shore palaeoenvironment. During first part Tortonian (P1), within prominent upwelling system supported diverse mesopredators, at least some which permanently resided embayment used it as nursery or breeding/calving area. Younger portions (P2) reveal more open setting, with wide-ranging species like rorquals increasingly dominating assemblage, but also local differences reflecting distance from coast. Like today, these ancient precursors modern Ecosystem were sardines, notably differed their present-day equivalent being dominated by extremely large-bodied apex predators Livyatan melvillei Carcharocles megalodon.