For millions of years, there were birds with false teeth. I do not mean dentures. That would be terrifying. No, a particular subgroup of birds called the Odontopterygiformes were the sole group of birds to evolve tooth-like spikes along their beaks in a sinister avian grin. Of these birds, which originated about 56 million years ago, among the largest and most recent was the 2.5 million year old bird Pelagornis mauretanicus. Known from fossils found in Morocco, this soaring avian looked something like an albatross with a serrated beak. But, if not teeth, what were those spikes and how did they grow?

The earliest birds had true teeth. Naturalists have known this since the late 19th century, and this transitional feature