Miocene stratigraphy and vertebrate paleontology along the western side of Cerros Cadena de los Zanjones (East Pisco Basin, Peru)

The Miocene Pisco Formation (East Pisco Basin, Peru) is renowned for its abundant, well-preserved fossils of marine vertebrates, representing one of the most spectacular and complete records of Neogene marine vertebrates worldwide. Here, we present a geological map at 1:10,000 scale investigating the spatial and temporal distribution of fossil vertebrates at Cerros Cadena de los Zanjones, in the Ica River Valley. Stratigraphic and paleontological analyses reveal the widespread occurrence of marine vertebrate remains in the Tortonian (10.0–8.6 Ma) P1 and Tortonian–Messinian (8.4–6.9 Ma) P2 sequences. These include 91 specimens preserved as bony elements, including cetaceans (both Odontoceti and Mysticeti), seals (Pinnipedia) and bony fishes (Osteichthyes). Elasmobranchs, including Carcharhiniformes, Lamniformes and Myliobatiformes, are represented by some 300 teeth. The P1-P2 passage is marked by faunal novelties such as the first appearance of seals. Overall, the assemblage taxonomically resembles that of the nearby, well-investigated site of Cerro Colorado.