We had to save our favorite for last. Thought the Oviraptor was weird? Well, nature decided to outdo herself and make one in Extra Large: the Gigantoraptor. Just look at this insane animal! It was 16 feet tall, weighted 2 tons, and likely sported colorful feathers. Paleontologists remain flummoxed by how it moved and what it ate: the lack of sharp teeth suggest vegetation was on the menu, but then why the enormous claws? Whatever it dined on, Gigantoraptor was easily the Biggest Bird of all time. Artwork by NTamura.