Big Bird.

By Miss Cellania in Animals & Pets on Jul 3, 2007 at 6:57 am

The prehistoric South American bird Argentavis magnificens had a wingspan of 23 feet! That makes this bird about the same size as a Cessna light aircraft. Scientists think Argentavis was too big and heavy to flap its wings, but could fly by taking advantage of thermals and updrafts. Link