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Warm southern winters
Cantrill, D. J., 2001. Cretaceous high-latitude terrestrial ecosystems: an
example from Alexander Island, Antarctica: VII International Symposium on
Mesozoic Terrestrial Ecosystems, p. 39-44.
...The polar Cretaceous flora from Alexander Island is unusual in its high
within floral diversity of liverworts when compared to lower latitude
floras. High within floral diversity of liverworts appears to be a feature
of high-latitude vegetation during periods of greenhouse warmth.
High-latitude Cretaceous (Aptian to Albian) floras in southeastern Australia
(c. 60-80degrees S) also have a high liverwort diversity (21% Aptian; 15%
Albian). In contrast, lower latitude floras of Australia (e.g. Queenlsand;
Walkom, 1918, 1919) apparently lack liverworts. A similar situation occurs
between Antarctica and South America. In the Aptian of Antarctica (Cerro
Negro Formation) liverworts make up c. 20% within floral diversity. In
comparison the lower latitude floras of the Aptian Baquero Formation have
over 96 plat taxa (Riccardi, 1988), but only one liverwort species (Halle,
1911). It is possible that the unique conditions of polar WARMTH (my stress
on this) coupled with a strongly seasonal light regime favours these
Hmmm...a warm winter...hmm...
But that's not all...
Cesari, S. N., Remesal, M, and Parica, C., 2001, Ferns; a palaeoclimate
significant component of the Cretaceous flora of Livingston Island,
Antarctica. VII International Symposium on Mesozoic Terrestrial Ecosystems,
The esistence of these familes in the Cerro Negro flora suggest a FROST-FREE
(me again) climate during the Aptian. Also, Cantrill (1998) suggests that
the presence of Lophosoria cupulatus indicates that the MAT was at least
8degreesC in the southern High Latitudes (that's above freezeing right?) in
the southern high latitudes. The current knowledge of the unquestionable
presence of Osmundaceae, Cyatheaceae, Lophosoriaceae, Marattiaceae and the
possible presence of Schizaeaceae, Lygodiaceae and Polypodiaceae allow us to
recognize ferns as a diverse group in the Early Cretaceous plant communities
of the South Shetlands Islands. According to the present requirements of
those families, some of which are restricted to montane forests, tropical
and subtropical, the climate was mild enough YEAR around, so that these
ferns could reach an important ecological role in the community, which is
reflected in the fossil record.
Several macro and microfossil ferns taxa were present during the Early
Cretaceous in the Antarctic region. These belong to several families
including the Osmundaceae, Marattiaceae, Cyatheaceae, and Lophosoriaceae
with the probable representation of Schizaeaceae, Lygodiaceae and
Polypodiaceae. Many of the taxa found in the strata belong to ferns, which
now live in wet tropical to subtropical forests. Moreover, some of them
could develop arborescent habit, therefore very cold conditions are
UNTENABLE (me again) in the area during the early Aptian.
Tracy L. Ford
P. O. Box 1171
Poway Ca 92074