17. The Ledumahadi Mafube Was the Largest Animal in the World
Twice as big as the African elephant, the Ledumahadi Mafube was the biggest animal on Earth, weighing in at 26,000 pounds. It was related to the brontosaurus and lived around 200 millions years ago. It used to live in today’s Argentina, and CNN describes it as having crouched and thick forelimbs to support the body. The Ledumahadi Mafube might have evolved from two-legged ancestors, and when it switched to a vegetarian-based diet, it evolved to walking on four legs to adapt its digestive system.