Pelagornis sandersi

Largest bird that ever flew?

Pelagornis sandersi
A reconstruction of the giant seabird Pelagornis sandersi. Artist: Liz Bradford

June 7, 2014 — Paleontologists have identified the fossilized remains of what could be the biggest flying bird ever found. With an estimated wingspan of between 20 and 24 feet, it surpasses the previous record holder, the extinct Argentavis magnificens, and is twice as big as the Wandering Albatross (Diomedea exulans), which has the longest wingspan of any living bird.

Scheduled to appear online the week of July 7, 2014, in the journal Proceedings of the National Academy of Sciences, the findings show that the creature was an extremely efficient glider, with long slender wings that helped it stay aloft despite its enormous size.

The remains of this bird were first unearthed in 1983 near Charleston, South Carolina, when construction workers began excavations for a new terminal at the Charleston International Airport. The specimen was so big they had to dig it out with a backhoe. "The upper wing bone alone was longer than my arm," said author Dan Ksepka of the National Evolutionary Synthesis Center in Durham, North Carolina.

From Wikipedia: The wandering albatross has the largest wingspan of any living bird, typically ranging from 2.51 to 3.5 m (8 ft 3 in to 11 ft 6 in), with a mean span of 3.1 m (10 ft 2 in) in the Bird Island, South Georgia colony and an average of exactly 3 m (9 ft 10 in) in 123 birds measured off the coast of Malabar, New South Wales. The longest-winged examples verified have been about 3.7 m (12 ft 2 in). Even larger examples have been claimed, with two giants reportedly measuring 4.22 m (13 ft 10 in) and 5.3 m (17 ft 5 in) but these reports remain unverified. As a result of its wingspan, it is capable of remaining in the air without flapping its wings for several hours at a time travelling 22 m for every meter of drop. (source)

Now in the collections at the Charleston Museum, the strikingly well-preserved specimen consisted of multiple wing and leg bones and a complete skull. Its sheer size and telltale beak allowed Ksepka to identify the find as a pelagornithid, an extinct group of giant seabirds known for the bony tooth-like spikes that lined their upper and lower jaws. Named 'Pelagornis sandersi' after retired Charleston Museum curator Albert Sanders, who led the fossil's excavation, the bird lived 25 to 28 million years ago — after the dinosaurs died out, but long before the first humans evolved.

Researchers have no doubt that P. sandersi flew. It's paper-thin hollow bones, stumpy legs and giant wings would have made it at home in the air, but clumsy on land. But because it exceeded what some mathematical models say is the maximum body size possible for flying birds, what was less clear was how it managed to take off and stay aloft despite its massive size.

Pelagornis sandersi: A glider

To find out, Ksepka fed the fossil data into a computer program designed to predict flight performance given various estimates of mass, wingspan and wing shape. P. sandersi was probably too big to take off simply by flapping its wings and launching itself into the air from a standstill, analyses show. Like Argentavis, whose flight was described by a computer simulation study in 2007, P. sandersi may have gotten off the ground by running downhill into a headwind or taking advantage of air gusts to get aloft, much like a hang glider.

Once it was airborne, Ksepka's simulations suggest that the bird's long, slender wings made it an incredibly efficient glider. By riding on air currents that rise up from the ocean's surface, P. sandersi was able to soar for miles over the open ocean without flapping its wings, occasionally swooping down to the water to feed on soft-bodied prey like squid and eels.

"That's important in the ocean, where food is patchy," said Ksepka, who is now Curator of Science at the Bruce Museum in Greenwich Connecticut.

Researchers hope the find will help shed light on why the family of birds that Pelagornis sandersi belonged to eventually died out, and add to our understanding of how the giants of the skies managed to fly.

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Pelagornis sandersi