GALLIFORMES

Dyke, Gareth J., Gulas, Bonnie E. & Crowe, Timothy M., 2003, Suprageneric relationships of galliform birds (Aves, Galliformes): a cladistic analysis of morphological characters, Zoological Journal of the Linnean Society 137 (2), pp. 227-244 : 227-228

ORDER GALLIFORMES

The living birds classified within the order Galliformes form a large and cosmopolitan group comprising more than 250 species within some 70 genera ( Monroe & Sibley, 1990) that are found on almost all continents across the globe (del Hoyo, Elliott &

Corresponding author. G. J. Dyke, Department of Zoology , University College Dublin, Belfield, Dublin 4, Ireland. E-mail: [e-mail]

Sargatal, 1994). The order contains a number of very familiar taxa, such as pheasants, grouse, Old World quails, partridges, and guineafowls ( Numididae ), as well as a number of somewhat less well known birds including the ‘mound-building’ megapodes, the scrubfowl and brush-turkeys ( Megapodiidae ), as well as the guans, chachalacas and curassows ( Cracidae ; Delacour & Amadon, 1973), and New World quails ( Odontophoridae ). Even though the history of galliform classification was reviewed extensively by Sibley & Ahlquist (1990), it is worth noting that from the inception of avian taxonomy (e.g. Linnaeus, 1758; Huxley, 1867; Garrod, 1874; Fürbringer, 1888; Sharpe, 1891; Gadow, 1893; Beddard, 1898) these birds have consistently been grouped together (yet the composition of families within the order has varied; see Sibley & Ahlquist, 1990). Overall, avian anatomists have considered Galliformes to be an osteologically uniform group (e.g. Lowe, 1938; Verheyen, 1956; Delacour, 1977), although much debate has focused on the question of whether the enigmatic hoatzin ( Opisthocomus hoazin ) should also be classified within the order (e.g. Fürbringer, 1888; Seebohm, 1890; Gadow, 1893; Shufeldt, 1904; Sibley & Ahlquist, 1973, 1990; Cracraft, 1981; Mindell et al., 1997; Hughes & Baker, 1999; Hughes, 2000).

From the results of their now classic DNAhybridization study, Sibley & Ahlquist (1990) recognized two distinct lineages within their superorder Gallomorphae (equivalent to the ‘traditional’ order Galliformes of most earlier workers), Craciformes and Galliformes ( Fig. 1A ). Representing a departure from the majority of older avian classifications, Sibley & Ahlquist (1990) removed Megapodiidae and Cracidae as a separate clade distinct from the remaining ‘phasianoid’ taxa ( Fig. 1A ). Most older classifications, albeit not couched within a strictly phylogenetic context, had at least implied a sequence of derivation for these birds within a single, distinct grouping (e.g. Verheyen, 1956, 1961; Johnsgard, 1973, 1986; Fig. 1B ).

Order Galliformes generally has been considered to be one of the more basal clades of modern birds (= Neornithes sensu Cracraft, 1986). Current classifications (e.g. del Hoyo et al., 1994) suggest that the order comprises at least five distinct families, namely Megapodiidae (megapodes and relatives), Numididae (guineafowl), Phasianidae (pheasants and relatives), Odontophoridae (New World quails), and Cracidae (curassows and relatives; Wetmore, 1960; Cracraft, 1981; Sibley & Ahlquist, 1990). Most often, Galliformes (‘landfowl’) have been placed within a basal neornithine clade along with the Anseriformes (‘waterfowl’) that has been termed Galloanserae or Galloanserimorphae (dependant on implied rank; e.g. Cracraft, 1988; Dzerzhinsky, 1995; Livezey, 1997; Groth & Barrowclough, 1999; see Zusi & Livezey, 2000 for further commentaries; see also Ericson, 1996, 1997 for an alternative view).

Figures

Figure 1. Two previous hypotheses for the internal relationships of Galliformes: A, Sibley & Ahlquist (1990: fig. 357). B, Johnsgard (1986: fig. 3; reproduced with permission, Oxford University Press).