David Hatcher Childress

"He's huge, he's huge, he's really, really big." So said pilot John Bouker about the gigantic bird the size of a small airplane that he and several others reported seeing flying over southwest Alaska in October 2002. According to the Anchorage Daily News on October 15 that year, Bouker had been skeptical when he had heard other reports of giant birds. Then he and his airplane passengers saw it for themselves. Scientists still are not sure what Bouker and others observed.

Such sightings are not as rare as you might think. They have been reported in many places from ancient times to today. Sightings vary. Some of the giants resemble known birds, such as eagles, but in sizes unimaginable. Others look very much like the long—extinct pterodactyl or pteranodon.

Could living dinosaurs exist? David Hatcher Childress, author of...