Phys.org has an interesting story about some truly giant birds.  The bird fossils, discovered in the 1980s, show that an extinct group of birds, the pelagornithids, had some large members not long after the mass extinction that killed off the dinosaurs, 65 million years ago.  One specimen, which lived about 50 million years ago, had a wingspan of about 21 feet (6.4 meters).  Another, which lived about 40 million years ago, is part of a jaw bone.  Read all about it in a paper in the journal Scientific Reports

“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.

Peter A. Kloess et al, Earliest fossils of giant-sized bony-toothed birds (Aves: Pelagornithidae) from the Eocene of Seymour Island, Antarctica, Scientific Reports (2020). DOI: 10.1038/s41598-020-75248-6