You'd think that being a contender for the largest animal that ever lived would be enough awesomeness for Amphicoelias Fragillimus, but you'd be wrong. This enormous sauropod also has an alluring history. The wunderkind paleontologist Edward Drinker Cope discovered its vertebrae in the 1870s, realized it was a huge finding (literally), and shipped the fossils away. They were either lost or stolen, and only in Cope's drawings and field notes remain, making Amphicoelias a very controversial species. Regardless of this mystery, check out how massive paleontologists estimate it was compared to other sauropods! Are we the only ones who want to take one out for a spin? Artwork by Vladimir Nikolov.