Sad but true: one of the largest flying birds to ever exist is extinct. Meet Argentavis, the teratornithid heavyweight champion from Argentina. This feathered colossus tipped the scales at a whopping 70 kg on average. For context, that's about the weight of a full-grown mountain goat.

With a wingspan between 5 and 7 metres, Argentavis was less "bird" and more "feathered aircraft". To get airborne, Argentavis often relied on wind assistance or a running start. These giants were the masters of the lazy glide, preferring to soar rather than flap. Flapping was reserved for short bursts, like when they spotted a particularly tempting prehistoric snack.

Sadly, climate change, declining prey, and increased competition (including the arrival of humans) signalled the final descent for this species.