What were the pelagornis sandersi predators?

The pelagornis sandersi, being an extinct species, existed millions of years ago. Thus, the composition of its predators would be different from nowadays. In the late Paleocene, the oceans were inhabited by various top predators, including species like the megalodon (a giant shark), the basilosaurus (a large whale-like reptile), and various species of mosasaurs. Additionally, other large aquatic birds like the dasornis and the osteocolax could also compete with pelagornis sandersi for food, posing a potential threat to its survival.