In order to identify the northern latitudinal limit between mangroves composed of Avicennia only and diversified mangroves during the Cenozoic thermal maxima, a special attention was paid to the Middle Miocene Climatic Optimum (MMCO: 17–14 Ma) in the Mediterranean s.l. region, including the Mediterranean Basin s.s. and its former brackish appendix, the Paratethys (Popescu et al., accepted, Journ. Biogeogr.). 

Pollen data come from forty-five biostratigraphically well-dated marine samples from 8 locations belonging to the MMCO. Information on the age and stratigraphy of some of the locations can be found in the following papers: Jiménez-Moreno et al., 2008, Journ. Biogeogr., 35, 1638-1649 (Göllenrsdorf); Jiménez-Moreno & Suc, 2005, Palaeogeogr. Palaeoclimatol. Palaeoecol., 253, 224-241 (Alboran A1, Estagel, Bayanne, La Rierussa); Besson et al., 2005, C.R. Geoscience, 337, 1045-1054 (Châteauredon).

The data have been performed and interpreted using a robust botanical background for identification of pollen grains and their representativeness in marine coastal sediments. Pollen grains have been botanically identified by comparison with large modern pollen collections developed from sampling of flowers in herbariums, especially on the basis of an accurate morphological examination of the pollen grains. Pollen counts are at least of 100 to 150 pollen grains per sample, the most abundant taxon, usually Pinus in the Mediterranean marine sediments, being excluded.

These data have been already used for reconstruction of vegetation and climate history in the Mediterranean region, particularly for past-climate quantification, establishment of the thermal palaeo-gradient in Europe during the Miocene and estimate of palaeo-elevation of the nearby mountains (e.g., see: Fauquette et al., 2007, The Micropalaeontological Soc., Spec. Publ.,The Geological Soc., 481-502; Fauquette et al., 2015, Earth Planet. Sci. Lett., 412, 220-234). They can be reused for any synthesis on the Miocene vegetation and climate reconstruction.