The term 'Amazonian' refers to the Amazon rainforest, which is located in South America and is the largest tropical rainforest in the world. It is home to a variety of animals, including capybaras and piranhas, which are both native to the region. Capybaras are the world's largest rodents and can weigh up to 140 pounds, while piranhas are carnivorous fish that have sharp teeth and powerful jaws. Both capybaras and piranhas are iconic animals of the Amazon rainforest and are often associated with the region.