The Biggest Bird That Ever Flew

It seems only fitting that a bird the size of a Cessna, one of the largest ever to fly, would be discovered while digging for an airport.

When excavations began on a new terminal for the Charleston International Airport in 1983, a volunteer for the Charleston Museum, James Malcom discovered a new fossil for what would go on to be called the Palagornis sandersi. Named for the museum's curator, Albert Sanders, the P. sandersi's skull had tooth-like spikes in the jaws, which indicated that the fossil was from a previously unknown species of Pelagornithidae, a group of giant seabirds that went extinct in the Pliocene era.

On account of their thin bones, bird fossils are hard to come by, but even once researchers realized that they had the rare, fairly complete skeleton, they were left guessing at things like feather length and the bird's mass. As size increases, so does the power required to fly. Could a bird like P. sandersi, whose wingspan stretches 20-24 feet—twice as far as the largest bird flying today—fly? Looking at its little legs and big wings, it sure looked like it would've had to, but no one could figure out how it pulled it off.

Daniel T. Ksepka, curator of the Bruce Museum in Greenwich Connecticut, just published an article in the Proceedings of the National Academy of Sciences stating that despite being above some theoretical upper limits for powered flight, the P. sandersis were masterful gliders.

Using computer modeling and 24 different combinations of mass estimates, aspect ratios, and wingspans, Ksepka was able to demonstrate a few different models of how the bird flew. Despite being two to four times larger than an albatross, the P. sandersi's twice-as-wide wingspan allowed it to fly and remarkably efficiently too. Ksepka compared the extinct bird to two of the largest and most efficient seabirds of today, the albatross and frigatebird.

Like its rival to the crown of “largest bird ever to fly,” the Argentavis magnificens, it seems unlikely that the P. sandersi could achieve flapping flight, or just take off from standing still. Some models have the P. sandersi taking off with a running start, like albatrosses do today. Other models hold that, like modern-day frigatebirds, P. sandersi couldn't land and take off in the water. Its pseudo-teeth do seem to lend themselves to hunting by snatching and grabbing prey while flying low over the ocean.

The specifics of flight are just one set of questions remaining about the P. sandersi. The Pelagornithidae seem to be some of the most efficient flyers ever, and they have been found on all seven continents, ruling for tens of millions of years. How did they ever go extinct, then 3 million years ago?

Their extinction narrowly precedes the appearance of modern humans, so we don't get to take credit—as awesome as it would be to have eaten a bird named “Sanders” out of existence.