Temporal range: Oligocene-Holocene, 25–0 Ma
Determining the relationships of both groups has been problematic. Flamingos had been placed with numerous branches within Neognathae, such as ducks and storks. The grebes had been placed with the loons. However recent studies have confirmed these two branches as sister groups.
Both primitive phoenicopteriformes and their closest relatives, the grebes, were highly aquatic. This indicates that the entire mirandornithe group evolved from aquatic, probably swimming ancestors.
According to Mayr (2004) and Sangster (2005) there are at least twelve distinct morphological synapomorphies that are unique to this clade:
- "At least the fourth to seventh cervical vertebrae strongly elongate, with processus spinosus forming a marked ridge.
- Humerus with a marked oval depression at insertion site of musculus scapulohumeralis cranialis.
- At least 23 presacral vertebrae.
- At least four thoracic vertebrae fused to a notarium.
- Distal end of ulna with marked oval depression radialis.
- Phalanx proximalis digiti majoris very elongate and narrow craniocaudally.
- Distal rim of condylus medialis of tibiotarsus distinctly notched.
- Pars acetabularis of musculus iliotibialis lateralis absent.
- Pars caudalis of musculus caudofemoralis absent.
- Wing with 12 primaries
- Left arteria carotis reduced or absent.
- Eggs covered with a chalky layer of amorphous calcium phosphate."
- Sangster, G. (2005) A name for the flamingo-grebe clade. Ibis. 147:612–615.
- Van Tuinen, M. Butvill, D. B. Kirsch, J. A. & Hedges, S. B. (2001) Convergence and divergence in the evolution of aquatic birds. Proc. R. Soc. B 268(1474):1345–1350 doi:10.1098/rspb.2001.1679.
- Chubb, A. L. (2004a) New nuclear evidence for the oldest divergence among neognath birds: The phylogenetic utility of ZENK (i). Molecular Phylogenetics and Evolution. 30(1):140–151. doi:10.1016/S1055-7903(03)00159-3.
- Mayr, G. (2004). Morphological evidence for sister group relationship between flamingos (Aves: Phoenicopteridae) and grebes (Podicipedidae). Zoological Journal of the Linnean Society, 140(2), 157-169 doi:10.1111/j.1096-3642.2003.00094.x.
- Fain, M. G. Houde, P. (2004) Parallel radiations in the primary clades of birds. Evolution 58(11):2558–2573. DOI:10.1554/04-235.
- Ericson, P. G. P. Anderson, C. L. Britton, T. Elzanowski, A. Johansson, U. S. Kllersj, M. Ohlson, J. I. & Parsons, T. J. (2006) Diversification of Neoaves: integration of molecular sequence data and fossils. Biology Letters. 2(4):543–547. doi:10.1098/rsbl.2006.0523.
- Hackett, S. J. et al. (2008) A phylogenomic study of birds reveals their evolutionary history. Science 320(5884):1763–1768. doi:10.1126/science.1157704.
- 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. doi:10.1126/science.1253451.