Antarctic Peninsula Seymour Island

The Late Eocene La Meseta Formation of Seymour Island contains floras that document climate change. Leaves and wood of both angiosperm and conifer affinity occur with fern fossils and a flower (Case, 1988; Reguero et al., 2002; Francis et al., 2004). Middle Eocene Nothofagus leaves were found to be notophyllous (a leaf-size category 7.5-12.5 cm long). Angiosperm fossils affiliated to families including Nothofagaceae, Dilleniaceae, Myrica-ceae, Myrtaceae, Elaeocarpaceae, Moraceae, Cunoniaceae, Winteraceae and Lauraceae have been described (Gandolfo et al., 1998a,b; Reguero et al.. 2002; Francis et al., 2004). Doktor et al. (1996) also described leaves affiliated with Podocarpaceae, Araucariaceae, Nothofagaceae and Proteaceae. Gothan (1908) was the first to describe fossil wood from Seymour Island, which has subsequently been re-examined by several authors and identified as having both angiosperm and coniferous affinities (Francis, 1991; Torres et al., 1994; Brea, 1996, 1998; Francis and Poole, 2002; Reguero et al., 2002).

Decrease in leaf sizes during the Late Eocene suggests that climate deteriorated towards the end of the Eocene, as observed in studies of the La Meseta Formation by Case (1988) and Reguero et al. (2002). Gandolfo et al. (1998a,b) suggested a MAT of 11-13°C for the Cucullaea I Allomember during the early Late Eocene. Further climate data were provided by leaf margin analyses of a Late Palaeocene flora (Cross Valley Formation) and of the early Late Eocene Cucullaea 1 flora, which indicate a decrease in floral diversity and a change from mean annual temperatures of 14°C in the Late Palaeocene to 11 °C in the early Late Eocene, with signs of freezing winters in the Late Eocene (Francis et al., 2004).

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