By Rebecca Morelle
Science Correspondent, BBC News
The giant bird would have been an elegant flier, able to soar across the ancient ocean in search of food
The fossilised remains of the largest flying bird ever found have been identified by scientists.
This creature would have looked like a seagull on steroids - its wingspan was between 6.1 and 7.4m (20-24ft).
The 25m-year-old fossil was unearthed 30 years ago in South Carolina, but it has taken until now to identify that this is a new species.
Daniel Ksepka, curator of science at the Bruce Museum in Connecticut, said: "This fossil is remarkable both for the size, which we could only speculate on before the discovery, and for the preservation.
"The skull in particular is exquisite.
"And given the delicate nature of the bones... it is remarkable that the specimen made it to the bottom of the sea, became buried without being destroyed by scavengers, fossilised, and then was discovered before it was eroded or bulldozed away."
The researchers believe this huge bird surpasses the previous recorder-holder, Argentavis magnificens - a condor-like bird from South America with an estimated wingspan of 5.7-6.1m (19-20ft) that lived about six million years ago.