This order comprises four families:

• Procellariidae (petrels, shearwaters)
• Hydrobatidae (northern storm petrels)
• Oceanitidae (southern storm petrels)
• Diomedeidae (albatrosses)

Genus-level phylogeny of extant Procellariiformes according to the results of Estandía et al. (2021), with the distribution of each family being indicated by the colour-code used throughout this website (Distribution code). Note that the four genera of Hydrobatidae recognised here may also be united in the broader genus Hydrobates. 

References

Estandía A, Chesser RT, James HF, Levy MA, Ferrer Obiol J, Bretagolle V, González-Solís J, and Welch AJ (2021), Substitution rate variation in a robust procellariiform seabird phylogeny is not solely explained by body mass, flight efficiency, population size or life history traits, bioRxiv (pdf)

Ferrer-Obiol J, James HF, Chesser RT, Bretagnolle V, González-Solís J, Rozas J, Riutort M, and Welch AJ (2021), Integrating sequence capture and restriction site-associated DNA sequencing to resolve recent radiations of pelagic seabirds, Sys. Biol. syaa101. (pdf)

Ferrer-Obiol J, Herranz JM, Paris JR, Whiting JR, Rozas J, Riutort M, and González-Solis J (2023), Species delimitation using genomic data to resolve taxonomic uncertainties in a speciation continuum of pelagic seabirds, Mol. Phylogenet. Evol. 179, e:107671. (free pdf)

Grosser S, Robertson F, Shepherd LD, Tennyson AJD, Miskelly CM, Taylor GA, and Robertson BC (2021), Phylogenetic affinities of the Whenua Hou Diving Petrel: implications for conservation, Emu 121, 102-112. (abstract)

Sausner J, Torres-Mura JC, Robertson J, and Hertel F (2016), Ecomorphological differences in foraging and pattering behavior among storm-petrels in the eastern Pacific Ocean, Auk 133, 397-414. (pdf)