| Summary
The Cenozoic was an important period in Earth's climatic
history, since it records the change from greenhouse climates
during the early Palaeogene to icehouse climates in the Neogene.
In particular, the record of this major climate transition
in the Southern Hemisphere is important because it involves
the initiation and development of the Antarctic ice sheet,
which now exerts a major control on our global climate.
Fossil plants from Palaeogene strata on Seymour Island, Antarctica,
are being investigated to determine the nature of vegetation
response to climate change in southern high latitudes. The
fossil assemblages represent vegetation which once grew on
the terrestrial volcanic arc that now forms the Antarctic
Peninsula, but which was subsequently washed into the adjacent
sedimentary basin and preserved within shallow marine sediments.
The presence of temperate vegetation at palaeolatitudes of
approximately 65°S (approximately the same latitude as
snow-covered Seymour Island today) indicates that the Antarctic
experienced much warmer climates during the early Cenozoic.
Analyses of Palaeocene floras have identified 36 angiosperm
leaf morphotypes, along with pteridophytes, and podocarp and
araucarian conifers. The angiosperm assemblage is dominated
by leaves with affinities to extant families typical of cool-warm
temperate (e.g. Nothofagaceae, Proteaceae) and sub-tropical
(e.g. Lauraceae, Sterculiaceae) vegetation.
Physiognomic analysis of angiosperm leaf assemblages using
CLAMP analysis has determined a mean annual temperature of
13.5 ± 0.7°C for the late Palaeocene. These warm
temperatures in Antarctica during the early Cenozoic indicate
that the climate was warm enough to sustain large forests
with relatively high diversity, even at such high-latitudes.
Eocene floras show decreasing diversity and increased dominance
by cool-temperate Nothofagus as a response to cooler, more
seasonal climates (mean annual temperature 10.8°C) that
ultimately led to the onset of the Cenozoic ice age.
Click
here to view results from the Antarctic field season
2001 which are posted on the NERC
web site.
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| This is a branch of an araucarian
conifer (Monkey Puzzle tree) of Eocene age, from
Seymour Island, Antarctica. It is beautifully
preserved in 3D within a carbonate nodule. |
Impression fossil of angiosperm
(flowering plant) leaves from the Palaeocene of
Seymour Island, Antarctica.
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The cold icy scenery around Seymour
Island today - it is hard to imagine that 50 million
years ago this area was covered with lush green
forests. |
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Fantastic exposure
of Palaeocene and Eocene sedimentary rocks on
Seymour Island, Antarctica. |
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