Ancient animal extinctions in Amazon disrupted nutrient flow

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.