Ammonites have been an important fossil group for the fields of evolution, paleoceanography, biostratigraphy, and paleoecology. Its diversity, its presence in a wide variety of marine environments and its easily conserved shells explain its usefulness in both paleontological and geological studies. Colombia is a country with a high occurrence of fossil ammonoids, even so, there are a very limited number of reports regarding its diversity and paleoecology. The purpose of this project is to identify the diversity of Cretaceous ammonites in the Rosa Blanca Formation, in a particular rock layer with a high concentration of these fossils at La Virgen West locality, in the town of Zapatoca, Santander. For this, fossil samples were collected, to later be analyzed and classified according to their morphological characteristics. Subsequently, four morphotypes were identified that match with known taxa described in the consulted literature, and finally a short discussion on the diversity of this layer, changes exhibited by some of the taxa along ontogeny and implications for future paleobiogeographic studies are presented.
