Patagopteryx (Patagopteryx deferrariisi), prehistoric bird, artwork. This species, depicted here following a herd of sauropods, lived in Patagonia, Argentina around 80 million years ago. With only small wings and no wishbone, they were unable to fly. However its skeleton reveals that ancestors of Patagopteryx could once fly, making it the earliest example of secondary flightlessness in bird evolution. The discovery of numerous feathered dinosaur fossils support the theory that modern day birds evolved from prehistoric theropod dinosaurs.