BBC:
In the late Pleistocene about 12 000 years ago, 97 genera of
large animals went extinct, primarily in the Americas and
Australia. The loss had a large impact on plant life, which
depended on vital nutrients distributed via the animals' dung.
In
a
paper published in
Nature Geoscience, researchers describe how they
developed a mathematical model to calculate the impact on the
ecosystem nutrient biogeochemistry. They found, for example,
that the extinctions resulted in a 98% reduction in the
dispersal of phosphorus, a key mineral for both animals and
plants. Even today, the Amazon basin has less phosphorus than
other areas, which, the researchers say, may be "partially a
relic of an ecosystem without the functional connectivity it
once had." Why the animals became extinct is unknown, but it
could be due to any of several causes, including human hunting,
climate change, disease, or Earth's colliding with an asteroid.
The researchers say that their model could also forecast the
consequences of large-animal extinctions today.
