The largest flying bird that ever lived?

[Still Waters]

Imagine an albatross with a hacksaw for a mouth. Set that strange creature about 50 million years in the past and you’ve got the image of a pelagornithid, a group of ancient avians that included some of the largest flying birds of all time. And now paleontologists have uncovered in that group what may be the largest known flying birds ever, with wingspans of roughly 20 feet.

The new study documenting the birds, published today in Scientific Reports, is the result of a fossil detective story spanning from Antarctica to California. By comparing a pair of polar fossils to the remains of related birds, paleontologists have been able to identify the early history of enormous fliers that were some of the first birds capable of soaring across seas.

https://www.smithsonianmag.com/science-nature/scientists-reveal-what-may-be-largest-flying-bird-ever-180976128/

[Eldorado]

I've known a few birds with a hacksaw for a mouth.

[Wepwawet]

This is an interesting bird as it shows the limitations of evolution in trying to re-invent something the birds ancestors had, and then lost. No toothed birds, or pterosaurs, survived the extinction, so this non toothed descendant of the surviving bird lineages evolved to fill a gap left by, probably not a bird, but by the Azhdarchidae, the huge pterosaurs probably better recognized by the name of their most famous member, Quetzalcoatlus.

The Pelagornithid clearly evolved to need teeth, but the genetic blueprint had long gone, or was so deep down and dormant that it was not possible to reactivate it. This is why there will not be a toothed and tailed "Chickenosaurus", or "Jurassic Park". So evolution, instead of re-inventing the wheel, was only able to form these protusions coming out of the beak in order to deal with a changing diet. It also shows just how rare, and this is unique, evolution tries to bring back what was lost. The "Terror Birds" could have done with teeth as they tried to fill the role of their "raptor" ancestors, but no luck, and they managed anyway with just an axe beak.