| Summary: | In recent years, the correlation between diatom and cetacean richness patterns through time has been deeply investigated. However, the comparison of diatom and cetacean global data sets faced some criticisms, due to the gaps characterizing the cetacean fossil record, contrasting with the well-known Cenozoic fossil record of diatom. Moreover, other studies pointed out the tight and complex relationships existing between biodiversity, primary productivity, and trophic interactions: changes in one or more of these parameters could have had drastic effects on the stability of past marine ecosystems. For example, it has been observed that the stability of these ecosystems could be dramatically threatened in response to changes in the feeding habits of animals occupying the top of the trophic chains, notably the hypercarnivores. With the aim to provide a contribute to this debate, we undertook an in-depth investigation of Cerro Colorado (middle Miocene, Pisco Formation, Peru), the rich locality where the holotype of the giant raptorial sperm whale Livyatan melvillei and many other well preserved fossil marine vertebrates outcroup from diatom beds. Nowadays, diatoms constitute the base of marine food chains off Peru, and their abundance enriches the biodiversity of fish feeding on them. Therefore, the wealth of fossil vertebrates in the Pisco-Ica desert could be related to the great abundance of food resources that characterized the area during the Neogene. Interestingly, the analysis of worldwide data sets indicated a maximum of diversity for both cetaceans and diatoms during the middle-late Miocene, a time interval including the Livyatan assemblage of Cerro Colorado. During five successive campaigns, all the vertebrate fossils surrounding the Livyatan type locality, on a surface of about 4 km2, were mapped using GPS equipment and preliminarily identified in the field, whereas the most significant specimens were collected for preparation. The study of a large sample of specimens attributed to the beaked whale ...
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