Short tailed monkey

The squirrel monkey is native to the Amazon rainforest. As the rainforest receives more rainfall over the years, the squirrel monkey will evolve to have a bumpy hand to easily grip the slippery surface caused by the rain. Also, since the Amazon rainforest will receive more rain, the tails will be shorter to prevent it from absorbing a lot of rain and weighing the monkeys down while climbing or doing other activities.