Mirandornithes () is a

clade A clade (), also known as a monophyletic group or natural group, is a group of organisms that are monophyletic – that is, composed of a common ancestor and all its lineal descendants – on a phylogenetic tree. Rather than the English term, ...

that consists of

flamingos Flamingos or flamingoes are a type of wading bird in the family Phoenicopteridae, which is the only extant family in the order Phoenicopteriformes. There are four flamingo species distributed throughout the Americas (including the Caribbean) ...

and

grebes Grebes () are aquatic diving birds in the order (biology), order Podicipediformes . Grebes are widely distributed freshwater birds, with some species also found in sea, marine habitats during Bird migration, migration and winter. Some flightless ...

. Many scholars use the term Phoenicopterimorphae for the superorder containing flamingoes and grebes. Determining the relationships of both groups has been problematic. Flamingos had been placed with numerous branches within

Neognathae Neognathae (; ) is a infraclass of birds, called neognaths, within the class Aves of the clade Archosauria. Neognathae includes the majority of living birds; the exceptions being the tinamous and the flightless ratites, which belong instead to ...

, such as

ducks Duck is the common name for numerous species of waterfowl in the family Anatidae. Ducks are generally smaller and shorter-necked than swans and geese, which are members of the same family. Divided among several subfamilies, they are a form t ...

and

storks Storks are large, long-legged, long-necked wading birds with long, stout bills. They belong to the family called Ciconiidae, and make up the order Ciconiiformes . Ciconiiformes previously included a number of other families, such as herons and ...

. The grebes had been placed with the

loon Loons (North American English) or divers (British / Irish English) are a group of aquatic birds found in much of North America and northern Eurasia. All living species of loons are members of the genus ''Gavia'', family Gaviidae and order Gavi ...

s. However recent studies have confirmed these two branches as sister groups. Both primitive

phoenicopteriformes Phoenicopteriformes is a group of water birds which comprises flamingos and their extinct relatives. Flamingos (Phoenicopteriformes) and the closely related grebes ( Podicipedidae) are contained in the parent clade Mirandornithes. Fossil rec ...

and their closest relatives, the

grebe Grebes () are aquatic diving birds in the order Podicipediformes . Grebes are widely distributed freshwater birds, with some species also found in marine habitats during migration and winter. Some flightless species exist as well, most notably ...

s, were highly aquatic.Mayr, G. (2014) The Eocene ''Juncitarsus'' – its phylogenetic position and significance for the evolution and higher-level affinities of flamingos and grebes. ''Comptes Rendus Palevol''. 13(1):9-18. https://doi.org/10.1016/j.crpv.2013.07.005 This indicates that the entire mirandornithe group evolved from aquatic, probably swimming ancestors.

Synapomorphies

According to Mayr (2004) and Sangster (2005) there are at least twelve distinct morphological

synapomorphies In phylogenetics, an apomorphy (or derived trait) is a novel character or character state that has evolved from its ancestral form (or plesiomorphy). A synapomorphy is an apomorphy shared by two or more taxa and is therefore hypothesized to have ...

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 The term calcium phosphate refers to a family of materials and minerals containing calcium ions (Ca2+) together with inorganic phosphate anions. Some so-called calcium phosphates contain oxide and hydroxide as well. Calcium phosphates are white ...

References

{{Taxonbar, from=Q5891686 Neognathae