The Pteroclididae (sandgrouse) were formerly included in the order Columbiformes largely due to their reported ability to drink by the "sucking" or "pumping" action of peristalsis of the esophagus ("The only other group, however, which shows the same behaviour, the Pteroclididae, is placed near the doves just by this doubtlessly very old characteristic."[4] ); more recently, it had been reported that they cannot drink by "sucking" or "pumping",[5] and were treated separately in the order Pteroclidiformes and were considered to be closer to the shorebirds.[6] Recent phylogenomic studies support the grouping of these pigeons and sandgrouse together, along with mesites, forming the sister taxon to Mirandornithes.[7][8][9][10]
The Columbidae are usually divided into five subfamilies, probably inaccurately. For example, the American ground and quail doves, which are usually placed in the Columbinae, seem to be two distinct subfamilies.[11] The order presented here follows Baptista et al. (1997)[12] with some updates.[13][14][15]
Osteology and DNA sequence analyses[15][16] indicate the dodo and Rodrigues solitaire are better considered as a subfamily Raphinae in the Columbidae pending availability of further information.
The arrangement of genera and naming of subfamilies is in some cases provisional, because analysis of different DNA sequences yield results that differ, often radically, in the placement of certain (mainly Indo-Australian) genera. This ambiguity, probably caused by long branch attraction, seems to confirm the first pigeons evolved in the Australasian region, and that the "Treronidae" and allied forms (crowned and pheasant pigeons, for example) represent the earliest radiation of the group.
The dodo and Rodrigues solitaire are in all likelihood part of the Indo-Australian radiation that produced the three small subfamilies mentioned above, with the fruit-doves and pigeons (including the Nicobar pigeon). Therefore, they are here included as a subfamily Raphinae, pending better material evidence of their exact relationships.
Exacerbating these issues, columbids are not well represented in the fossil record. No truly primitive forms have been found to date. The genus Gerandia has been described from Early Miocene deposits of France, but while it was long believed to be a pigeon,[17] it is now considered a sandgrouse.[18] Fragmentary remains of a probably "ptilinopine" Early Miocene pigeon were found in the Bannockburn Formation of New Zealand and described as Rupephaps; "Columbina" prattae from roughly contemporary deposits of Florida is nowadays tentatively separated in Arenicolumba, but its distinction from Columbina/Scardafella and related genera needs to be more firmly established (e.g. by cladistic analysis). Apart from that, all other fossils belong to extant genera. For these, and for the considerable number of more recently extinct prehistoric species, see the respective genus accounts.