In Persian mythology, a roc is a giant bird of prey, able to carry off live elephants. The roc can be found in Middle-Eastern literature as early as the 8th century CE. Explorer Marco Polo first brought the roc to the attention of the Western world in his highly embellished 13th century travelogue, and the gigantic bird also appears multiple times in The Arabian Nights.
There has never been evidence of a real bird of prey approaching the supposed size of the roc, which Marco Polo describes as having a wingspan of 48 feet (15 meters). Its feathers are said to be 24 feet (7 meters) long, and its egg more than 150 feet (46 meters) in circumference. Tales of the roc seem to have been a perfect opportunity for authors to practice hyperbole. Despite the fact that there is no giant bird of prey known to science, giant birds have existed, such as the extinct elephant bird of Madagascar, which Marco Polo may well have encountered in his travels. The elephant bird was 10 feet (3 meters) tall and flightless, resembling today's ostrich.
The roc has parallels in many cultures throughout the world, including the folklore of Native Americans, European Jews, and the Chinese. Some believe that stories of the roc have some basis in fact. As with dragons, ideas of the roc may have been informed by fossil finds in ancient times, before people had the tools to correctly interpret them. It has also been postulated that the roc was inspired by the appearance of the sun during an eclipse, which somewhat resembles a bird - the same theory has been used to explain the phoenix of Egyptian mythology.
Another theory is that the roc is a misinterpretation of actual animals that seemed strange to the observers, a common problem with natural history before the days of the camera. Such an animal could become larger and gain features and abilities in every retelling. Some large birds of prey can carry off baby lambs, and this sight may have inspired tales of the roc's behavior with elephants. Large, flightless birds such as the elephant bird may also be the basis for the legendary roc.