The fossil record of
P. pervetus includes many complete skeletons from
Green River Formation sites (
Early Eocene), suggesting that the birds nested in colonies and that they possibly died due to
volcanism or
botulism, the latter of which is similar to many colony-nesting
waterfowl or
shorebirds today.
P. recurvirostra is known from a partial wing (
KUVP 10105) found in the
Colton Formation, from the
Late Paleocene to
Early Eocene sediments of the
Wasatch Plateau near Ephraim,
Utah. However,
Headonornis is now referred to as a stem group representative of the
Phoenicopteriformes. The holotype and paratypes of "
P."
mongoliensis are known from the
Early Eocene of
Mongolia, but these fragmentary specimens are poorly preserved and they likely belong to a stem
Phoenicopterimorphae, not a presbyornithid. Undescribed fossils are also known from the Paleocene of
Utah. ==Description==