RECENT PERSPECTIVES ON THE FORMATION OF THE ISTHMUS OF PANAMA

The formation of the Isthmus of Panama stands as one of the greatest natural events of the Cenozoic, driving profound biotic transformations on land and in the oceans. Some recent studies (Bacon et al., 2015; Montes et al., 2015), using biological and sediment provenance lines of evidence, respectively, suggest that the Isthmus formed many millions of years earlier than the widely recognized age of approximately 3 Ma, a result that if true would revolutionize our understanding of environmental, ecological, and evolutionary change across the Americas. To bring clarity to the question of when the Isthmus of Panama formed an exhaustive review and reanalysis of geological, paleontological, and molecular records is presented (O’Dea et al., 2016). These independent lines of evidence converge upon a cohesive narrative of gradually emerging land and constricting seaways, with formation of the Isthmus of Panama sensu stricto around 2.8 Ma (Figure 1). At present, no solid evidence exists for a land bridge in place before this time. As discussed in recent publications (Erkens and Hoorn, 2017, O’Dea, 2017), complex geo-biotic environments, e.g., the Panamanian Isthmus, require more than a few new studies to resolve the lacking knowledge. There remain great opportunities for multidisciplinary research on this topic with a marked need to refine the model of Isthmus formation, especially in relation to the shifting paleogeography and paleoceanography of ancient interoceanic connections and how those shifts affected marine and terrestrial biota. The geologic community, particularly in the region, should explore on the bridges that can be built through the scientific discourse.