Eocene Origin

The Caribbean mangroves, as part of Atlantic-Eastern Pacific (AEP) mangroves, are usually considered descendants of a purported Cretaceous pantropical mangrove belt that underwent regional differentiation after the tectonic closure of the Tethys Sea by the African barrier. This view, largely based on the scattered presence of Nypa and Acrostichum in a number of localities, changes if we use a quantitative community approach with emphasis on mangrove-forming trees. Such analysis reveals that there is no evidence for the occurrence of mangrove ecosystems during the Cretaceous and the Paleocene, and the first robust evidence for true mangrove communities appears in the Middle Eocene (~50–40 Ma). These first mangroves were dominated by the only mangrove-forming tree existing at that time, Pelliciera, and exhibited a characteristic sea–land zonation with Nypa and Acrostichum in the back-mangrove brackish swamps and some palms, including the salt-intolerant Mauritia, in the inland freshwater wetlands. Pelliciera first appeared along the southern Caribbean coasts in the Early Eocene and gained prominence in the Middle Eocene as it spread throughout the Caribbean region. This suggests that the initial mangroves in the Caribbean were ecological and evolutionary advancements that emerged de novo during the Eocene period, rather than being a result of regional evolutionary divergence from hypothetical Late Cretaceous Tethyan mangroves. The existence of these Tethyan mangroves is not substantiated by quantitative palynological records.