Prophaethontidae is an extinct family of Early

Paleogene The Paleogene ( ; British English, also spelled Palaeogene or Palæogene; informally Lower Tertiary or Early Tertiary) is a geologic period, geologic period and system that spans 43 million years from the end of the Cretaceous Period million yea ...

phaethontiforms that include the genera '' Lithoptila'' and '' Prophaethon'', as well as possibly '' Phaethusavis''. The anatomy of the prophaethontids were more similar to those of members of the order Procellariiformes than to Phaethontidae, features including nostrils that are long and slit-like, with longer wings and legs. This suggests that prophaethontids were better at swimming and being more pelagic and surface-feeding than tropicbirds are today. Such features were suggested to link the phaethontiforms with the procellariiforms, but molecular studies do not support this and instead support a relationship between phaethontiforms and the order Eurypygiformes.Braun, E.L. & Kimball, R.T. (2021) Data types and the phylogeny of Neoaves. ''Birds'', 2(1), 1-22; https://doi.org/10.3390/birds2010001

Reference

{{Taxonbar, from=Q18608894 Seabirds Prehistoric bird families