is actually a very close relative of
pheasants The living Galliformes were once divided into seven or more
families. Despite their distinctive appearance, grouse and
turkeys probably do not warrant separation as families due to their recent origin from
partridge- or
pheasant-like birds. The turkeys became larger after their ancestors colonized temperate and subtropical
North America, where pheasant-sized competitors were absent. The ancestors of grouse, though, adapted to harsh climates and could thereby colonize
subarctic regions. Consequently, the
Phasianidae are expanded in current taxonomy to include the former
Tetraonidae and
Meleagrididae as
subfamilies. The
Anseriformes (
waterfowl) and the Galliformes together make up the
Galloanserae. They are
basal among the living
neognathous birds, and normally follow the
Paleognathae (ratites and tinamous) in modern bird classification systems. This was first proposed in the
Sibley-Ahlquist taxonomy and has been the one major change of that proposed scheme that was almost universally adopted. However, the Galliformes as they were traditionally delimited are called
Gallomorphae in the Sibley-Ahlquist taxonomy, which splits the
Cracidae and
Megapodiidae as an
order "
Craciformes". This is not a natural group, however, but rather an erroneous result of the now-obsolete
phenetic methodology employed in the Sibley-Ahlquist taxonomy. Phenetic studies do not distinguish between
plesiomorphic and
apomorphic characters, which leads to
basal lineages appearing as
monophyletic groups. Historically, the
buttonquails (Turnicidae),
mesites (Mesitornithidae) and the
hoatzin (
Opisthocomus hoazin) were placed in the Galliformes, too. The former are now known to be
shorebirds adapted to an inland lifestyle, whereas the mesites are probably closely related to
pigeons and doves. The relationships of the hoatzin are entirely obscure, and it is usually treated as a
monotypic order Opisthocomiformes to signify this. The fossil record for the Galliformes is incomplete. }} }}
Evolution Galloanserae-like birds were one of the main survivors of the
K-T Event, that killed off the rest of the dinosaurs. The dominant birds of the dinosaur era were the
enantiornithes, toothed birds that dominated the trees and skies. Unlike those enantiornithes, the ancestors of the galliformes were a niche group that were toothless and ground-dwelling. When the asteroid impact killed off all non-avian dinosaurs, and the dominant birds, it destroyed all creatures that lived in trees and on open ground. The enantiornithes were wiped out, but the ancestors of galliformes were small and lived in the ground (unlike water for
Anseriformes) which protected them from the blast and destruction.
Fossils of these galliform-like birds originate in the
Late Cretaceous, most notably those of
Austinornis lentus. Its partial left
tarsometatarsus was found in the
Austin Chalk near
McKinney, Texas, dating to about 85 million years ago (Mya). This bird was quite certainly closely related to Galliformes, but whether it was a part of these or belongs elsewhere in the little-known galliform branch of Galloanserae is not clear. However, in 2004, Clarke classified it as a member of the larger group
Pangalliformes, more closely related to chickens than to ducks, but not a member of the
crown group that includes all modern galliformes. Another specimen,
PVPH 237, from the Late Cretaceous
Portezuelo Formation (
Turonian-
Coniacian, about 90 Mya) in the
Sierra de Portezuelo (
Argentina) has also been suggested to be an early galliform relative. This is a partial
coracoid of a neornithine bird, which in its general shape and particularly the wide and deep attachment for the muscle joining the coracoid and the
humerus bone resembles the more
basal lineages of galliforms. Additional galliform-like pangalliformes are represented by
extinct families from the
Paleogene, namely the
Gallinuloididae,
Paraortygidae and
Quercymegapodiidae. In the early
Cenozoic, some additional birds may or may not be early Galliformes, though even if they are, they are unlikely to belong to extant families: • †
Argillipes (London Clay Early Eocene of England) • †
Coturnipes (Early Eocene of England, and Virginia, USA?) • †
Palaeophasianus (Willwood Early Eocene of Bighorn County, USA) • †
Percolinus (London Clay Early Eocene of England) • †
Amitabha (Bridger middle Eocene of Forbidden City, USA) – phasianid? • †
"Palaeorallus" alienus (middle Oligocene of Tatal-Gol, Mongolia) • †
Anisolornis (Santa Cruz Middle Miocene of Karaihen, Argentina) From the mid-
Eocene onwards – about 45 Mya or so, true galliforms are known, and these completely replace their older relatives in the early
Neogene. Since the earliest representatives of living galliform families apparently belong to the
Phasianidae – the youngest family of galliforms, the other families of Galliformes must be at least of
Early Eocene origin but might even be as old as the Late Cretaceous. The
ichnotaxon Tristraguloolithus cracioides is based on fossil eggshell fragments from the Late Cretaceous
Oldman Formation of southern
Alberta, Canada, which are similar to
chachalaca eggs, but in the absence of bone material, their relationships cannot be determined except that they are apparently
avian in origin. Modern genera of phasianids start appearing around the
Oligocene-
Miocene boundary, roughly 25–20 Mya. It is not well known whether the living genera of the other, older, galliform families originated around the same time or earlier, though at least in the New World quail, pre-Neogene forms seem to belong to genera that became entirely extinct later on. A number of Paleogene to mid-Neogene fossils are quite certainly Galliformes, but their exact relationships in the order cannot be determined: • †Galliformes gen. et sp. indet. (Oligocene) – formerly in
Gallinuloides; phasianid? • †
Palaealectoris (Agate Fossil Beds Early Miocene of Sioux County, USA) – tetraonine?
List of major taxa For a long time, the pheasants, partridges, and relatives were indiscriminately lumped in the Phasianidae, variously including or excluding turkeys, grouse, New World quail, and guineafowl, and divided into two
subfamilies – the
Phasianinae (pheasant-like forms) and the
Perdicinae (partridge-like forms). This crude arrangement was long considered to be in serious need of revision, but even with modern
DNA sequence analyses and
cladistic methods, the
phylogeny of the Phasianidae has resisted complete resolution. '' skeleton, , Paris A tentative list of the higher-level galliform
taxa, listed in evolutionary sequence, is: • †
Archaeophasianus Lambrecht 1933 (Oligocene? – Late Miocene) • †
Argillipes Harrison & Walker 1977 • †
Austinornis Clarke 2004 [
Pedioecetes Baird 1858] (Austin Chalk Late Cretaceous of Fort McKinney, USA) • †
Chambiortyx Mourer-Chauviré et al. 2013 • †
Coturnipes Harrison & Walker 1977 • †
Cyrtonyx tedfordi (Barstow Late Miocene of Barstow, USA) • †
Linquornis Yeh 1980 (middle Miocene) • †
Namaortyx Mourer-Chauviré, Pickford & 2011 • †
Palaeorallus alienus Kuročkin 1968 nomen dubium • †
Sobniogallus Tomek et al. 2014 • †
Tristraguloolithus Zelenitsky, Hills & Curri 1996 [ootaxa- cracid?] • †
Procrax Tordoff & Macdonald 1957 (middle Eocene? – Early Oligocene) • †
Paleophasianus Wetmore 1940 • †
Taoperdix Milne-Edwards 1869 (Late Oligocene) • Family †
Gastornithidae? Fürbringer, 1888 •
Gastornis Hébert, 1855 (vide Prévost, 1855) [Diatryma Cope, 1876] (Paleocene-Eocene) • Family †
Sylviornithidae? Thus, the bulk of the Phasianidae was alternatively treated as a single subfamily Phasianinae. The grouse, turkeys, true pheasants, etc., would then become
tribes of this subfamily, similar to how the Coturnicinae are commonly split into a quail and a spurfowl tribe. In 2021, Kimball
et al. found the family to comprise three distinct subfamilies, with two containing multiple genera; these results were followed by the
International Ornithological Congress. The partridge of
Europe is not closely related to other partridge-like Galliformes, as already indicated by its
sexually dimorphic coloration and possession of more than 14
rectrices, traits it shares with the other advanced phasianids. However, among these its relationships are obscure; it is unclear whether it is closer to the turkeys or to certain short-tailed pheasants like
Ithaginis,
Lophophorus,
Pucrasia, and
Tragopan. In 2021, Kimball
et al. found it to belong to the subfamily
Phasianini, alongside the true pheasants. ==Phylogeny==