Biology Reference
In-Depth Information
The fossil record shows that during this time there was extinction of entire
ecosystems, extensive modifi cation of others, and that by the end of the
Tertiary period the eight ancient ecosystems of the Cretaceous had been
modifi ed into or replaced by twelve essentially modern environments and
biotic communities that presently extend across the landscapes of the New
World.
The record further tells us that changes were beginning to happen at
a faster pace in the late Neogene, raising expectations about events to fol-
low in the near future. One of the hallmarks of vegetation history studies
for the Quaternary is that the high resolution allows detecting in compara-
tively great detail the effects of rapid and signifi cant as well as compara-
tively minor changes in climate on the Earth's vegetation cover. It may be
recalled that in the mid-1980s extensive press coverage showed midwest-
ern farmers sending loads of hay to the southeast where crops had been
devastated by an El Niño-induced drought. The change corresponded to a
temperature increase of about 0.5°C. This compares to changes of 6°C or
more just in the recent Holocene. The Neogene was another pivotal time
in ecosystem history because it set the stage for the latest modifi cation in
the range and composition of the Earth's biota, particularly at the level of
plant associations, in response to the considerable environmental fl uctua-
tions of the Quaternary period. The Quaternary, in turn, provides near-
term analogs for the effects of ongoing and anticipated environmental mod-
ifi cation of the Earth's ecosystems on which we depend and of which we
are a part.
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REFERENCES
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Rev. Chil. Hist. Nat.
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Ballantyne, A. P., N. Rybczynski, P. A. Baker, C. R. Harington, and D. White. 2006. Pliocene
Arctic temperature constraints from the growth rings and isotopic composition of fossil
larch.
Palaeogeogr. Palaeocl. Palaeoecol.
242:188-200.
Barreda, V. D., and E. Bellosi. 2003. Ecosistémas terrestres del Mioceno temprano de la Pata-
gonia central, Argentina: Primeros avances.
Rev. Mus. Argent. Cienc. Nat.
, n.s. 5:125-34.
Barreda, V. D., and M. Caccavari. 1992. Mimosoideae (Leguminosae) occurrences in the early
Miocene of Patagonia (Argentina).
Palaeogeogr. Palaeocl. Palaeoecol
. 94:243-52.
Berry, E. W. 1923. Tertiary fossil plants from the Republic of Haiti.
Proc. U.S. Natl. Mus.
62:1-10.
