Aequornithes Explained

Aequornithes should not be confused with Aequorlitornithes.

Aequornithes (from Latin aequor, expanse of water + Greek ornithes, birds), or core water birds, are defined as "the least inclusive clade containing Gaviidae and Phalacrocoracidae".^[1]

The monophyly of the group is currently supported by several molecular phylogenetic studies.^{[2] [3] [4] [5]}

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,^[6] in a clade later named Phaethoquornithes.^[7]

Cladogram based on Burleigh, J.G. et al. (2015)^[8] with some names after Sangster, G. & Mayr, G. (2021).

Notes and References

1. Mayr . Gerald . 2011 . Metaves, Mirandornithes, Strisores and other novelties – a critical review of the higher-level phylogeny of neornithine birds . Journal of Zoological Systematics and Evolutionary Research . 49 . 1 . 58-76 . 10.1111/j.1439-0469.2010.00586.x. free .
2. Hackett . S.J.. et al . 27 June 2008 . A phylogenomic study of birds reveals their evolutionary history . Science . 320 . 5884 . 1763–1768 . 18583609. 10.1126/science.1157704. 2008Sci...320.1763H. 6472805.
3. Yuri . T.. et al . 2013 . Parsimony and model-based analyses of indels in avian nuclear genes reveal congruent and incongruent phylogenetic signals. Biology . 2 . 1 . 419–444 . 24832669. 4009869. 10.3390/biology2010419. free.
4. Kimball . R.T.. et al . December 2013 . Identifying localized biases in large datasets: A case study using the Avian Tree of Life . Mol Phylogenet Evol . 69 . 3 . 1021–32 . 23791948. 10.1016/j.ympev.2013.05.029.
5. Kuramoto . T. . etal . 2015 . Determining the Position of Storks on the Phylogenetic Tree of Waterbirds by Retroposon Insertion Analysis . Genome Biology and Evolution . 7 . 12. 3180–3189 . 10.1093/gbe/evv213 . 26527652 . 4700946 .
6. Jarvis . E.D.. et al . 12 December 2014 . Whole-genome analyses resolve early branches in the tree of life of modern birds . Science . 346 . 6215 . 1320–1331 . 25504713. 4405904. 10.1126/science.1253451. 2014Sci...346.1320J.
7. 10.1016/j.avrs.2022.100027. Phylogenetic definitions for 25 higher-level clade names of birds . 2022 . Sangster . George . Braun . Edward L. . Johansson . Ulf S. . Kimball . Rebecca T. . Mayr . Gerald . Suh . Alexander . Avian Research . 13 . 100027 . 247988800 . free .
8. Burleigh . J.G.. et al . March 2015 . Building the avian tree of life using a large-scale, sparse supermatrix . Molecular Phylogenetics and Evolution . 84 . 53–63 . 25550149. 10.1016/j.ympev.2014.12.003.