Editing Frigatebird (section)

===Fossil record===
[[File:Limnofregata azygosternon.jpg|thumb|right|Fossil of Eocene species ''Limnofregata azygosternon'']]
The [[Eocene]] frigatebird genus ''[[Limnofregata]]'' comprises birds whose fossil remains were recovered from prehistoric freshwater environments, unlike the marine preferences of their modern-day relatives. They had shorter less-hooked bills and longer legs, and longer slit-like nasal openings.<ref name="mayr">{{cite book |last=Mayr |first=Gerald |title=Paleogene Fossil Birds |publisher=Springer Science & Business Media |location=New York|date=2009 |pages=63–64 |isbn=978-3-540-89628-9 |url=https://books.google.com/books?id=P_TB72RBLLMC&q=Limnofregata&pg=PA63}}</ref><!-- cites previous two sentences --> Three species have been described from fossil deposits in the western United States, two—''L. azygosternon'' and ''L. hasegawai''—from the [[Green River Formation]] (48–52 million years old) and one—''L. hutchisoni''—from the [[Wasatch Formation]] (between 53 and 55 million years of age).<ref name="stidham">{{cite journal|last=Stidham|first=Thomas A.| year=2014 |title=A new species of ''Limnofregata'' (Pelecaniformes: Fregatidae) from the Early Eocene Wasatch Formation of Wyoming: implications for palaeoecology and palaeobiology | journal=Palaeontology | pages=1–11|doi=10.1111/pala.12134 | volume=58|issue=2|s2cid=85200173 |doi-access=free}}</ref> Fossil material indistinguishable from living species dating to the [[Pleistocene]] and [[Holocene]] has been recovered from [[Ascension Island]] (for ''F. aquila''),<ref>{{cite journal|last=Ashmole | first=Nelson Philip |year=1963|title= Sub-fossil bird remains on Ascension Island | journal=Ibis | volume= 103 | issue=3 | pages=382–89 | doi=10.1111/j.1474-919X.1963.tb06761.x }}</ref> [[Saint Helena|Saint Helena Island]],<ref>{{cite journal|last=Olson | first=Storrs L. |year= 1975|title= Paleornithology of St. Helena Island, South Atlantic Ocean | journal=Smithsonian Contributions to Paleobiology | volume= 23 | issue=23 | pages= 1–49 | url=http://www.sil.si.edu/smithsoniancontributions/paleobiology/pdf_lo/SCtP-0023.pdf | doi=10.5479/si.00810266.23.1}}</ref> both in the southern Atlantic Ocean, and also from various islands in the Pacific Ocean (for ''F. minor'' and ''F. ariel'').<ref>{{cite journal|last=James | first=Helen F.  |year=1987|title= A late Pleistocene avifauna from the island of Oahu, Hawaiian Islands |journal=Documents des Laboratories de Géologie, Lyon|volume= 99| pages=221–30 | url=https://repository.si.edu/bitstream/handle/10088/11424/vz_james-87-documlabgeollyon-pleistocene_oahu.pdf?sequence=1}}</ref><ref>{{cite book |last=Steadman |first=David W. |year=2006 |title=Extinction and biogeography of tropical Pacific birds |publisher=University of Chicago Press |location=Chicago, Illinois |isbn=978-0-226-77142-7 |url=https://books.google.com/books?id=vBZXJQ3HDg0C&q=fregata}}</ref> A [[tarsometatarsus]] and [[pedal phalanx]] from the [[Lower Eocene]] [[London Clay]] of the [[Walton-on-the-Naze]] resembles ''Limnofregata'', but being notably larger and distinct in other ways, was tentatively referred to ''Marinavis longirostris'' due to similar stratigraphy, geography, size, and presumed frigatebird affinities.<ref>{{Cite journal |last1=Mayr |first1=Gerald |last2=Kitchener |first2=Andrew |date=2024 |title=A large frigatebird-like tarsometatarsus from the London Clay of Walton-on-the-Naze (Essex, UK) may shed light on the affinities of a poorly known early Eocene seabird taxon |url=https://www.app.pan.pl/article/item/app011692024.html |journal=Acta Palaeontologica Polonica |volume=69 |doi=10.4202/app.01169.2024|doi-access=free }}</ref>

A [[cladistics|cladistic]] study of the skeletal and bone morphology of the classical Pelecaniformes and relatives found that the frigatebirds formed a [[clade]] with ''Limnofregata''. Birds of the two genera have 15 [[cervical vertebrae]], unlike almost all other [[Ciconiiformes]], Suliformes and Pelecaniformes, which have 17. The age of ''Limnofregata'' indicates that these lineages had separated by the Eocene.<ref name=smith>{{cite journal | last= Smith | first= Nathan D. | year=2010 | title= Phylogenetic analysis of Pelecaniformes (Aves) based on osteological data: Implications for waterbird phylogeny and fossil calibration studies | journal= PLOS ONE | volume=5 | issue = 10 | page= e13354 | doi = 10.1371/journal.pone.0013354 | pmid=20976229 | pmc=2954798| bibcode= 2010PLoSO...513354S | doi-access= free }}</ref><!-- cites previous 4 sentences --><!-- {{cite journal | last1=Kennedy | first1=Martyn | last2=Spencer | first2=Hamish G. | year=2004 | title=Phylogenies of the frigatebirds (Fregatidae) and tropicbirds (Phaethonidae), two divergent groups of the traditional order Pelecaniformes, inferred from mitochondrial DNA sequences | journal=Molecular Phylogenetics and Evolution | volume=31 | issue=1 | pages=31–38 | doi=10.1016/j.ympev.2003.07.007 | pmid=15019606}} -->