Preface: La Guajira, Colombia: a new window into the Cenozoic neotropical biodiversity and the Great American Biotic Interchange

Over the past four years, we have conducted extensive fieldwork in the Cocinetas Basin of La Guajira Peninsula, including geological mapping, stratigraphic descriptions, and exhaustive paleontological collection of plants, microfossils, and marine and terrestrial invertebrates and vertebrates. Moreno et al. (Swiss J Paleontol 134: 1-39, 2015) provide an overview of these efforts, including a revised Neogene stratigraphy for Cocinetas Basin and redefined (Jimol and Castilletes formations) and newly named (Ware Formation) lithostratigraphic units. Hendy et al. (Swiss J Paleontol 134, 2015) utilize the extensive invertebrate fossil record of the basin to develop paleoenvironmental interpretations and a chronostratigraphic framework buttressed by 87Sr/86Sr isotopic analyses and biostratigraphy. This geological exploration highlights the tremendously diverse and important fossil assemblages throughout the Jimol, Castilletes and Ware formations. These new fossil data will be of great value for future paleobiogeographic, paleogeographic, paleooceanographic and paleoenvironmental interpretations. Already, the faunal and floral fossil record of Cocinetas Basin indicates that once the humid ecosystem of the Neogene underwent drastic climatic changes over the last two million years.