Mangrove distribution and diversity during three Cenozoic thermal maxima in the Northern Hemisphere (pollen records from the Arctic–North Atlantic–Mediterranean regions)

Aim Past pollen records reveal the changes in latitudinal distribution of plants relation to climate, particularly their expansion response global warming. The maximum northward mangrove genus Avicennia since Early Eocene is known, but this information missing for other taxa. Here, we evaluate diversity past mangroves with respect latitude during three Cenozoic thermal maxima (PETM: 56 Ma; EECO: 54–49 MMCO: 17–14 Ma). Location North Atlantic, Mediterranean. Taxa Avicennia, taxa (Rhizophoraceae, Nypa, Xylocarpus, Pelliciera, etc.). Method We collected well-dated marine sediments along a Northern Hemisphere transect and analysed content order compare present. analysis 89 samples 13; 31; 45) was performed interpreted using robust botanical background identification grains representativeness sediments. Results During Eocene, two palaeolatitudinal thresholds at 65–70°N 35°N, respectively, delimited Avicennia-only from diversified scrawny finally well-developed mangrove. threshold selective 40°N Mid-Miocene. range limit up 10–15° poleward Mid-Miocene compared 9° Main conclusions A buffer zone characterised by co-occurring few megathermal occurred between 35°N 65–70°N. This finding questions relative influence more ‘equable’ climate and/or ability some expand towards areas cooler conditions past. Mangrove provincialism, which established progressively after probably forced plate tectonics. taxonomic impoverishment Atlantic East Pacific province caused successive periods cooling. These results support Tethyan origin mangroves.