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of the Cretaceous; (2) a heyday for early and intermediate stem groups of
tropical organisms and communities around the late Paleocene / early Eo-
cene when tropical climates were of nearly global extent; (3) an important
period of adjustment in the late Eocene, Oligocene, and early Miocene af-
forded by greater environmental stability than in the periods immediately
before and after; (4) a golden age in the middle Tertiary for organisms
and assemblages capable of adjusting to seasonal temperature and precipi-
tation regimes; and (5) the turbulent climatic times at the beginning of
the Quaternary period around 2.6 Ma, when crown groups of older tropi-
cal lineages were reinvigorated by evolution, and more recent seasonally
dry-habitat groups underwent their initial period of rapid speciation and
radiation.
THE FUTURE OF CURRENT ECOSYSTEMS
As warming environmental trends continue, it is worth speculating on the
probable ecosystems of the future. In years to come, “nature” will surely
mean mostly parks, preserves, botanic gardens, and conservatories. Envi-
ronmentally, wildfi res and extreme weather will increase, and biotically
crop lands, range lands, and managed forests will be more extensive. Rem-
nants of former ecosystems will exist mostly in inaccessible places. There
will be an increase in competitive, aggressive, resistant, furtive organisms
comprising weedy and highly disturbed ecosystems; reduced tundra and
little alpine tundra / páramo; a greater array and a wider distribution of rap-
idly evolving organisms with warm-temperate to subtropical ecology (e.g.,
Gillman et al. 2009; see summary by Gill 2009); microorganisms and
pathogens with greater resistance to antibiotics diversifying and spreading
widely with continued global warming; a diminishing number of wild food
and drug plants for replenishing the genetic stock; and an increasing num-
ber of endangered species protected by laws that change with the political
climate until over time there will likely be few left to protect.
The current version of the Earth's living envelope began assembling
around 100 million years ago in the Late Mesozoic with eight compara-
tively simple ecosystems. There has been ample opportunity to observe the
effects of environmental change through a window into the past provided
by an extensive fossil record and an impressive array of innovative tech-
nologies. In view of what was accomplished by evolutionary and geologic
processes from the Late Mesozoic through the early part of the Anthropo-
gene, it seems we should be demanding far more vigorously a better legacy
for future generations.
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