Ameghino worked with Francisco P. Moreno, founder and director of the La Plata Museum, as deputy director, secretary, and director of the Paleontology Department upon its establishment in 1888. Ameghino enriched his department with his own collection, which he sold to the provincial government for the purpose. But it was little time in which these two scientists worked together. A year later his magnum opus appeared in the Proceedings of the National Academy of Sciences, "Mammalian Fossils in the Argentine Republic", comprising 1028 pages and an atlas. This latter contribution to the knowledge of the fossil mammals of Argentina won the bronze medal at the "Exposition Universelle" of 1889 in Paris.