| Summary: | General Summary I. Introduction, setting, and objectives The Pisco Formation (Mio-Pliocene, East Pisco basin, southern coast of Peru) is a shallow-marine sedimentary unit consisting of diatomaceous mudstones, siliciclastic sandstones and siltstones, nodular dolomite layers, tuffaceous beds, and minor conglomerates and phosphatic intervals. The Pisco Formation is known to vertebrate palaeontologists worldwide for its exceptional fossil record of marine vertebrates: this is perhaps the most significant record in the world for the Neogene, due to the excellent quality of preservation, the high concentration of fossils, and their remarkable diversity, which includes sharks and rays, bony fish, marine turtles and crocodiles, seabirds, baleen-bearing and echolocating toothed whales, pinnipeds, and sloths. Several decades of palaeontological research on the Pisco Formation fossil vertebrates have led to the description of tens of new taxa which ultimately allowed to write the evolutionary history of various lineages of marine mammals. The primary objective of the present dissertation is to contribute to a still-missing comprehensive understanding of the Pisco Formation fossil vertebrate assemblage, with a special focus on its palaeoecological aspects. II. Description and results of the research activities Extensive prospecting for fossil vertebrates in the vicinities of Ocucaje (Ica Region) allowed a first comprehensive evaluation of the palaeontological content of the strata of the Pisco Formation cropping out there. At two highly fossiliferous localities, Cerro Colorado and Cerro Los Quesos, a census of the fossil vertebrate remains was undertaken, and all the detected specimens were reported on a detailed stratigraphic basis. In a wider area along the western side of the Ica River, the Pisco Formation was recognized as comprised of three depositional sequences which bear distinct marine vertebrate assemblages. The still scarcely known oldest sequence (named P0) is poorly chronostratigraphically constrained, whereas ...
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