Ross Sea Region McMurdo Sound

Only two E/O floras have been described from East Antarctica - a significant, but ex situ, Middle-Late Eocene flora within glacial erratic boulders found at Minna Bluff (mentioned above), and a single Nothofagus leaf within the Early Oligocene strata of the CRP-3 core in McMurdo Sound

(Cantrill, 2001; Florindo et al., 2005). An additional single Nothofagus leaf was also found in the CIROS-1 core, originally thought to be Oligocene in age (Hill, 1989), but after recent refinement of the age model, it is now considered Early Miocene (Roberts et al., 2003). The McMurdo erratic flora comprises leaves, wood, seeds and Araucaria-type scale-leaves (Pole et al., 2000). Two species of Nothofagus leaves were found, some of which are interpreted as deciduous based on the interpretation of plicate vernation (venation with distinct folds). Fossil wood was identified as Araucarioxylon, Phyllocladoxylon and Nothofagoxylon (Francis, 1999, 2000). The CRP-3 Nothofagus leaf (compared to Nothofagus beardmorensis from the Sirius Group; Francis and Hill, 1996; Cantrill, 2001) was small and also had plicate vernation, but differs to the leaf in the CIROS-1 core thought to be of N. gunnii affinity, an alpine species from Tasmania (Hill, 1989; Francis, 1999).

The floras in the erratics indicate the presence of large forest trees comparable to those in South American araucarian (emergent) - Nothofagus forests in the Valdivian Andes of Chile or the Phyllocladus- and Nothofagus-dominated cool, sclerophyll forests of temperate New Zealand and Tasmania. Francis (1999, 2000) suggested a cool temperate climate, with a mean annual temperature of < 13 °C from the wood flora, considering some winter snow likely, but temperatures not cold enough to allow extensive ice to form at sea level. Single Nothofagus leaves found in the CRP-3 and CIROS-1 cores, from Early Oligocene and Early Miocene intervals, respectively, indicate, in conjunction with the palynomorphs, a cold temperate and periglacial climate at those times. The CRP-3 Early Oligocene vegetation is compared to low Nothofagus woodland in the Magellanic region of southern Chile (Francis and Hill, 1996; Cantrill, 2001). Cantrill (2001) compared it to N. beardmorensis, known from the Sirius Group and considered to have a minimum requirement of —22°C (which is probably conservative) with several weeks at least 5°C during the growing season. The Early Miocene Nothofagus leaf is different and may have come from a small-to medium-sized tree in a sub-alpine rainforest or shrub community probably <1m tall and living in exposed conditions (Hill, 1989; Francis, 1999).

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