This chapter summarizes the abundant marine paleobiological markers recorded in the Vaca Muerta Formation illustrating their richness, biodiversity, and application for age dating and paleobiogeographical global correlation. The markers described include ammonites, calcareous nannofossils, calcisphaeres (calcareous dinoflagellate cysts), calpionellids, coprolites, dinoflagellates, radiolarians, saccocomid microcrinoids, and trace fossils. Traditionally, the ammonites have been the best known and most relevant macroinvertebrate fossil group. Nevertheless, in the past decade, the exploration of the Vaca Muerta unconventional play has boosted the research on the micropaleontology of the area determining an extensive growth in knowledge and reported here.