Often called the Terror Bird, in the prehistoric age there was an animal called the Phorroracus and upon seeing its constructed skeleton at the Los Angeles Natural History museam, I felt like I was staring at the bones of a real life chocobo. It's about the same size and shape with the same features as your average say... Final Fantasy XI chocobo.

It was great to see, unfortunately I can't find any very good information online. I wonder if the design of the chocobo was based on this prehistoric animal? I suppose it's possible.