pelagornithids

Pelagornithids were a family of extinct, large, flightless seabirds that lived from the Late Paleocene to the Late Pliocene epochs. They are known from fossils found on every continent except Antarctica. These birds were characterized by their enormous size, with some species estimated to have had wingspans of up to 6 meters, making them among the largest flying birds known. A distinctive feature of pelagornithids was the presence of bony projections, or "pseudoteeth," on their jaws. These were not true teeth but rather extensions of the jawbone covered in keratin, likely used for grasping slippery prey like fish and squid.

The exact evolutionary relationships of pelagornithids are still debated, but they are generally placed within the order Pelecaniformes, which also includes pelicans and boobies. Their lifestyle was likely similar to modern albatrosses and petrels, spending much of their lives at sea and coming to land only to breed. Fossil evidence suggests they inhabited a wide range of marine environments. The decline and eventual extinction of pelagornithids are not fully understood, but it is thought to be related to climate change and shifts in oceanographic conditions towards the end of the Pliocene.