PIGEON

This family is a highly coherent group with no members showing obvious links with other bird families, or vice versa. The dodo and solitaires are clearly related, as discussed below, but equally lacking in obvious links with other bird families. The limited fossil record also consists only of unequivocal Columbidae species. Links to the sandgrouse and parrots have been suggested, but resemblances to the first group are due to convergent evolution[citation needed] and the second depend on the parrot-like features of the Tooth-billed Pigeon. However, the distinctive features of that bird seem to have arisen from its specialized diet rather than a real relationship to the parrots.

The family is usually divided into five subfamilies, but this is probably inaccurate. For example, the American ground and quail doves which are usually placed in the Columbinae seem to be two distinct subfamilies. The order presented here follows Baptista et al. (1997) with some updates (Johnson & Clayton 2000, Johnson et al. 2001, Shapiro et al. 2002).

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 that 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.

As the Dodo and Rodrigues Solitaire are in all likelihood part of the Indo-Australian radiation that produced the 3 small subfamilies mentioned above with the fruit-doves and -pigeons (including the Nicobar Pigeon), 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 which most likely belongs to the Columbinae has been described from Early Miocene deposits of France. Fragmentary remains of an indeterminate (probably "treronine") Early/Middle Miocene pigeon were found in New Zealand. Apart from that, all other fossils belong to extant genera. Fo