Ardei

Ardei is a possibly-paraphyletic suborder of order Pelecaniformes that include the families Ardeidae (herons, egrets, and bitterns) and Threskiornithidae (ibises and spoonbills).^[1][2][3] Traditionally the ardeids and threskiornithids were classified in the order Ciconiiformes along with Ciconiidae (storks), Phoenicopteridae (flamingos), Scopidae (hamerkop), Balaenicipitidae (shoebill), and even Cathartidae (New World vultures and condors).^[4][5] However, there were some osteological studies that have questioned the monophyly of Ciconiiformes, suggesting that the ardeids and threskiornithids originated from early gruiforms, with the latter being a transitionary taxon to order Charadriiformes.^[6] The non-monophyletic nature of Ciconiiformes is supported by recent genomic studies that have found support for threskiornithids, ardeids, scopids and balaenicipitids being closely related to Pelecanidae (pelicans).^[7][1][2]

Ardei Temporal range: Eocene–recent, 56–0 Ma PreꞒ Ꞓ O S D C P T J K Pg N
Grey heron (Ardea cinerea)
Sacred ibis (Threskiornis aethiopicus)
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Chordata
Class:	Aves
Order:	Pelecaniformes
Suborder:	Ardei Wagler, 1830
Families
Threskiornithidae †Xenerodiopidae Ardeidae

The exact relationship between ardeids, threskiornithids and suborder Pelecani is still being investigated with two hypotheses. One hypothesis is ardeids and threskiornithids are each other's sister taxon in suborder Ardei (as presented here).^[3] The other hypothesis is the ardeids are the sister taxon to the pelecanid-related clade, with threskiornithids the basal most group. This hypothesis is supported from some morphological and the earliest representations of non-threskiornithid pelecaniforms come from the Oligocene deposits in Africa, while threskiornithids have been found in Eocene deposits of North America and Europe.^[8]

References

1. Jarvis, E.D.; et al. (2014). "Whole-genome analyses resolve early branches in the tree of life of modern birds". Science. 346 (6215): 1320–1331. Bibcode:2014Sci...346.1320J. doi:10.1126/science.1253451. PMC 4405904. PMID 25504713.
2. Prum, Richard O.; Berv, Jacob S.; Dornburg, Alex; Field, Daniel J.; Townsend, Jeffrey P.; Lemmon, Emily Moriarty; Lemmon, Alan R. (2015). "A comprehensive phylogeny of birds (Aves) using targeted next-generation DNA sequencing". Nature. 526 (7574): 569–573. Bibcode:2015Natur.526..569P. doi:10.1038/nature15697. ISSN 0028-0836. PMID 26444237. S2CID 205246158.
3. International Ornithological Committee (25 July 2020). "Ibis, spoonbills, herons, hamerkop, shoebill, pelicans". IOC World Bird Names: Version 2.11. WorldBirdNames.org. Retrieved 4 January 2021.
4. Wetmore, A. (1960). "A classification for the birds of the world" (PDF). Smithsonian Miscellaneous Collections. 139 (11): 1–37.
5. Sibley, Charles G., and Ahlquist, Jon E. 1991. Phylogeny and Classification of Birds: A Study in Molecular Evolution. Yale University Press. ISBN 0-300-04085-7. Accessed January 4, 2021.
6. Olson, S.L. (1979). "Multiple origins of the Ciconiiformes". Proceedings of the Colonial Waterbird Group. 2: 165–170. doi:10.2307/1520951. JSTOR 1520951.
7. Yuri, T (2013). "Parsimony and model-based analyses of indels in avian nuclear genes reveal congruent and incongruent phylogenetic signals". Biology. 2 (1): 419–44. doi:10.3390/biology2010419. PMC 4009869. PMID 24832669.
8. Mayr, G. (2009). Paleogene Fossil Birds. Berlin: Springer Berlin Heidelberg. pp. 1–275. ISBN 978-3540896272.