Aequornithes

{{Short description|Clade of birds}}

{{distinguish|Aequorlitornithes}}

{{automatic taxobox

| fossil_range = Early Paleocene–Holocene {{fossilrange|62|earliest=Late Cretaceous|0|ref={{cite journal| doi = 10.1093/molbev/msj124| last1 = Slack| first1 = Kerryn E.| last2 = Jones| first2 = Craig M.| last3 = Ando| first3 = Tatsuro| last4 = Harrison| first4 = G.L. "Abby"| last5 = Fordyce| first5 = R. Ewan| last6 = Arnason| first6 = Ulfur| last7 = Penny| first7 = David| year = 2006| title = Early Penguin Fossils, plus Mitochondrial Genomes, Calibrate Avian Evolution| journal = Molecular Biology and Evolution| volume = 23| issue = #6| pages = 1144–1155| pmid = 16533822| citeseerx = 10.1.1.113.4549}} [http://mbe.oxfordjournals.org/cgi/content/full/msj124/DC1 Supplementary Material] {{Webarchive|url=https://web.archive.org/web/20091216110914/http://mbe.oxfordjournals.org/cgi/content/full/msj124/DC1 |date=December 16, 2009 }}}}

Possibly an earlier origin based on molecular clock{{cite journal | first1 = H. | last1 = Kuhl. | first2 = C. | last2 = Frankl-Vilches | first3 = A. | last3 = Bakker | first4 = G. | last4 = Mayr | first5 = G. | last5 = Nikolaus | first6 = S. T. | last6 = Boerno | first7 = S. | last7 = Klages | first8 = B. | last8 = Timmermann | first9 = M. | last9 = Gahr | year = 2020 | title = An unbiased molecular approach using 3'-UTRs resolves the avian family-level tree of life | journal = Molecular Biology and Evolution | volume = 38 | pages = 108–127 | doi = 10.1093/molbev/msaa191 | pmid = 32781465 | pmc = 7783168 | doi-access = free }}

| name = Aequornithes

| image = Thalassarche cauta - SE Tasmania.jpg

| image_caption = Shy albatross (Thalassarche cauta)

| taxon = Aequornithes

| authority = Mayr, 2010{{Cite journal | last1=Sangster | first1=G. | last2=Braun | first2=E.L. | last3=Johansson | first3=U.S. | last4=Kimball | first4=R.T. | last5=Mayr | first5=G. | last6=Suh | first6=A. | date=2022 | title=Phylogenetic definitions for 25 higher-level clade names of birds | journal=Avian Research | volume=13 | pages=100027 | doi=10.1016/j.avrs.2022.100027 | doi-access=free | bibcode=2022AvRes..1300027S }}

| subdivision_ranks = Clades

| subdivision =

• Gaviiformes
• Feraequornithes
  {{Small|Sangster & Mayr, 2021}}{{cite journal |last1=Sangster |first1=G. |last2=Mayr |first2=G. |title=Feraequornithes: a name for the clade formed by Procellariiformes, Sphenisciformes, Ciconiiformes, Suliformes and Pelecaniformes (Aves) |journal=Vertebrate Zoology |date=2021 |volume=71 |pages=49–53 |doi=10.3897/vertebrate-zoology.71.e61728|doi-access=free }}
• Austrodyptornithes
• Pelecanimorphae

}}

Aequornithes ({{IPAc-en|iː|k|w|ɔːr|ˈ|n|ɪ|θ|iː|z}}, from Latin aequor, expanse of water + Greek ornithes, birds), or core water birds, are defined in the PhyloCode as "the least inclusive crown clade containing Pelecanus onocrotalus and Gavia immer".{{Cite journal | last=Mayr | first=Gerald | date=2011 | title=Metaves, Mirandornithes, Strisores and other novelties – a critical review of the higher-level phylogeny of neornithine birds | journal=Journal of Zoological Systematics and Evolutionary Research | volume=49 | issue=1 | pages=58–76 | doi=10.1111/j.1439-0469.2010.00586.x| doi-access=free }}{{Cite journal |last1=Sangster |first1=George |last2=Braun |first2=Edward L. |last3=Johansson |first3=Ulf S. |last4=Kimball |first4=Rebecca T. |last5=Mayr |first5=Gerald |last6=Suh |first6=Alexander |date=2022-01-01 |title=Phylogenetic definitions for 25 higher-level clade names of birds |url=https://ueaeprints.uea.ac.uk/id/eprint/84494/1/1_s2.0_S2053716622000238_main.pdf |journal=Avian Research |volume=13 |pages=100027 |doi=10.1016/j.avrs.2022.100027 |issn=2053-7166|doi-access=free |bibcode=2022AvRes..1300027S }}

The monophyly of the group is currently supported by several molecular phylogenetic studies.{{Cite journal|last1=Hackett |first1=S.J.|display-authors=et al |date=27 June 2008 |title=A phylogenomic study of birds reveals their evolutionary history |journal=Science |volume=320 |issue=5884 |pages=1763–1768 |pmid= 18583609|doi=10.1126/science.1157704|bibcode=2008Sci...320.1763H|s2cid=6472805}}{{Cite journal|last1=Yuri |first1=T.|display-authors=et al |year=2013 |title=Parsimony and model-based analyses of indels in avian nuclear genes reveal congruent and incongruent phylogenetic signals|journal=Biology |volume=2 |issue=1 |pages=419–444 |pmid= 24832669|pmc= 4009869|doi=10.3390/biology2010419|doi-access=free}}{{Cite journal|last1=Kimball |first1=R.T.|display-authors=et al |date=December 2013 |title=Identifying localized biases in large datasets: A case study using the Avian Tree of Life |journal=Mol Phylogenet Evol |volume=69 |issue=3 |pages=1021–32 |pmid= 23791948|doi=10.1016/j.ympev.2013.05.029|bibcode=2013MolPE..69.1021K }}{{cite journal | last1 = Kuramoto | first1 = T. | display-authors = etal | year = 2015 | title = Determining the Position of Storks on the Phylogenetic Tree of Waterbirds by Retroposon Insertion Analysis | url= | journal = Genome Biology and Evolution | volume = 7 | issue = 12| pages = 3180–3189 | doi = 10.1093/gbe/evv213 | pmid = 26527652 | pmc = 4700946 }}

Aequornithes includes the clades Gaviiformes, Sphenisciformes, Procellariiformes, Ciconiiformes, Suliformes and Pelecaniformes. It does not include several unrelated groups of aquatic birds such as flamingos and grebes (Mirandornithes), shorebirds, gulls, and auks (Charadriiformes), or the Anseriformes (waterfowl).

Based on a whole-genome analysis of the bird orders, the kagu and sunbittern (Eurypygiformes) and the three species of tropicbirds (Phaethontiformes) together styled as the Eurypygimorphae are the closest sister group of the Aequornithes,{{Cite journal|last1=Jarvis |first1=E.D.|display-authors=et al |date=12 December 2014 |title=Whole-genome analyses resolve early branches in the tree of life of modern birds |journal=Science |volume=346 |issue=6215 |pages=1320–1331 |pmid= 25504713|pmc= 4405904|doi=10.1126/science.1253451|bibcode=2014Sci...346.1320J}} in a clade later named Phaethoquornithes.{{cite journal |doi=10.1016/j.avrs.2022.100027|title=Phylogenetic definitions for 25 higher-level clade names of birds |year=2022 |last1=Sangster |first1=George |last2=Braun |first2=Edward L. |last3=Johansson |first3=Ulf S. |last4=Kimball |first4=Rebecca T. |last5=Mayr |first5=Gerald |last6=Suh |first6=Alexander |journal=Avian Research |volume=13 |page=100027 |s2cid=247988800 |doi-access=free |bibcode=2022AvRes..1300027S }}