Fossils recovered from Antarctica in the 1980s represent the oldest giant members of an extinct group of birds that patrolled the southern oceans with wingspans of up to 21 feet (6.4 meters) that would dwarf the 11½-foot wingspan of today’s largest bird, the wandering albatross.
Called pelagornithids, the birds filled a niche much like that of today’s albatrosses and traveled widely over Earth’s oceans for at least 60 million years. Though a much smaller pelagornithid fossil dates from 62 million years ago, one of the newly described fossils—a 50 million-year-old portion of a bird’s foot—shows that the larger pelagornithids arose just after life rebounded from the mass extinction 65 million years ago, when the relatives of birds, the dinosaurs, went extinct. A second pelagornithid fossil, part of a jaw bone, dates from about 40 million years ago.
“Our fossil discovery, with its estimate of a 5-to-6-meter wingspan—nearly 20 feet—shows that birds evolved to a truly gigantic size relatively quickly after the extinction of the dinosaurs and ruled over the oceans for millions of years,” said Peter Kloess, a graduate student at the University of California, Berkeley.
The last known pelagornithid is from 2.5 million years ago, a time of changing climate as Earth cooled, and the ice ages began.
Kloess is the lead author of a paper describing the fossil that appears this week in the open access journal Scientific Reports. His co-authors are Ashley Poust of the San Diego Natural History Museum and Thomas Stidham of the Institute of Vertebrate Paleontology and Paleoanthropology at the Chinese Academy of Sciences in Beijing. Both Poust and Stidham received their Ph.Ds from UC Berkeley.
Birds with pseudoteeth
Pelagornithids are known as ‘bony-toothed’ birds because of the bony projections, or struts, on their jaws that resemble sharp-pointed teeth, though they are not true teeth, like those of humans and other mammals. The bony protrusions were covered by a horny material, keratin, which is like our fingernails. Called pseudoteeth, the struts helped the birds snag squid and fish from the sea as they soared for perhaps weeks at a time over much of Earth’s oceans.
Large flying animals have periodically appeared on Earth, starting with the pterosaurs that flapped their leathery wings during the dinosaur era and reached wingspans of 33 feet. The pelagornithids came along to claim the wingspan record in the Cenozoic, after the mass extinction, and lived until about 2.5 million years ago. Around that same time, teratorns, now extinct, ruled the skies.
The birds, related to vultures, “evolved wingspans close to what we see in