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Gruiformes

(Order)

Overview

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The diverse Gruiformes contains a considerable number of living and extinct bird families with, on first sight, little in common. Gruiform means "crane-like."

Traditionally, a number of wading and terrestrial bird families that did not seem to belong to any other order were classified together as Gruiformes. These include, the very large cranes, or the relatively small and secretive water-loving crakes and rails (families with a wide distribution and a dozen or more member species), as well as a variety of very small families, some of them containing very few species, such as the Heliornithidae, the limpkin, or the trumpeters.

The gruiformes are morphologically diverse birds, with little apparent similarity. However, anatomical evidence indicates that several groups within the traditional Gruiformes do appear to be evolutionarily related, and this is further supported by molecular analyses. Other birds have been placed in this order more out of necessity to place them somewhere; this has caused the expanded Gruiformes to lack distinctive apomorphies. Luckily for phylogeneticists, more recent studies indicate that these "odd Gruiformes" are if at all only loosely related to the cranes, rails, and relatives ("core Gruiformes"). A notable feature in several gruiform lineages is that flighlessness evolves far more easily than in most other birds. About one-third of the extinct families were at least partially flightless, and numerous living and extinct flightless rails are known.

Systematics

The Gruiformes have been further divided into suborders. The Rallidae and the Heliornithidae are united in the Ralli; although the Rallidae are sometimes separated as order Ralliformes, this is not supported by the current data.[1] Aramidae, Gruidae and the Psophiidae form the Grui. This arrangement is quite well-supported by the available molecular and morphological data.

A number of potential candidates for Gruiformes status have been rejected by Sibley & Ahlquist (1990) based on DNA-DNA hybridization studies. Their research led them to remove the Otididae, Eurypygidae, Rhynochetidae, Cariamidae, Mesitornithidae and Turnicidae from the Gruiformes. The Eurypygidae and Rhynochetidae were similar to the Ardeidae, and were therefore associated with certain birds that are traditionally interpreted as Ciconiiformes and others such as Charadriiformes in a vastly expanded Ciconiiformes. The Mesitornithidae and Cariamidae were indicated to be close to the Cuculiformes, but the Otididae did not seem to be close to other extant birds and on the placement of the Turnicidae they could reach no firm conclusion.

However, DNA-DNA hybridization is often insufficient to determine more than the most basic phylogenies; Sibley & Ahlquist's "Ciconiiformes" are not a natural group for example. While the families that they did not believe to belong to this group probably indeed do not do so, their proposed affinities according to Sibley and Monroe are generally seen as erroneous nowadays. Removing these taxa from the Gruiformes has the additional benefit of enabling the order to be defined by morphological apomorphies, as noted above.

DNA sequence analyses has led to the Plains Wanderer - which was formerly believed to be an aberrant buttonquail in the Gruiformes - being reassigned as a charadriiform wader related to jacanas (Paton et al. 2003, Thomas et al. 2004, van Tuinen et al. 2004). The buttonquails have in the meantime also turned out to be Charadriiformes, but form a lineage rather distinct from other members of that order (van Tuinen et al., 2005; Paton & Baker, 2006).

Fain & Houde (2004) found that the families split out of the Gruiformesby Sibley & Ahlquist do indeed seem to be distinct. Their data indicated that a motley clade of families might exist which they termed Metaves, but the suggested internal structure of these is hardly likely to be correct and the group as a whole is not robustly supported. Thus, the "Metaves" might be a pseudo-clade based on molecular homoplasies. However, the case for reducing the Gruiformes to a core of families is nonetheless strengthened as despite it not being known where the "odd" families should be placed, maintaining them in the Gruiformes is less and less supported either.

The kagu and sunbittern seem to constitute a distinct Gondwanan lineage, which might also include the extinct adzebills of New Zealand. Its relationship to the more distinct but possibly still somewhat related mesites and the core Gruiformes is unresolved. The seriemas and bustards are possibly lineages fairly basal in a clade uniting the "higher waterbirds", aquatic Neoaves such as Procellariiformes and Ciconiiformes but not the waterfowl which are Galloanserae.

The enigmatic Kagu may not be a gruiform

ORDER GRUIFORMES

The gruiforms are one of the older lineages of modern birds. Ancestral gruiforms were in all probability among the survivors of the Cretaceous–Tertiary extinction event c. 65 mya already. No unequivocal basal gruiforms are known from the fossil record. However, there are several genera which are not unequivocally assignable to the known families and which may occupy a more basal position:

Other even more enigmatic fossil birdsa re occasionally suggested to belong into this order, such as the proposed Late Cretaceous family Laornithidae and the following taxa:

Photos

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Taxonomy

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The Order Gruiformes is further organized into finer groupings including:

Families

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Aptornithidae

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Aramidae

The Limpkin (common names: carrao, courlan, crying bird), Aramus guarauna, is a bird that looks like a large , but is skeletally closer to cranes. It is found in marshes with some trees or scrub in the Caribbean, Central America and southern Florida. Its name derives from the seeming limp of the Limpkin when it walks. [more]

Brontornithidae

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Cariamidae

The Seriemas are a small and ancient family (Cariamidae) of tropical birds related to the rails and bustards. [more]

Dryornithidae

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Eogruidae

[more]

Ergilornithidae

[more]

Eurypygidae

The Sunbittern, Eurypyga helias is a -like bird of tropical regions of the Americas, and the sole member of the family Eurypygidae (sometimes spelled Eurypigidae) and genus Eurypyga. [more]

Gastornithidae

[more]

Geranoididae

[more]

Gruidae

Cranes are large, long-legged and long-necked of the order Gruiformes, and family Gruidae. Unlike the similar-looking but unrelated herons, cranes fly with necks outstretched, not pulled back. There are representatives of this group on all the continents except Antarctica and South America. [more]

Gryzajidae

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Heliornithidae

The Heliornithidae are a small of tropical birds with webbed lobes on their feet similar to those of grebes and coots. The family overall are known as finfoots, although one species is known as a Sungrebe. Finfoots somewhat resemble rails, they have long necks, slender bodies, broad tails and sharp pointed bills. They have a diverse range of calls, but do not call frequently. Their legs and feet are brightly colored and, unlike grebes, they are capable of walking well and even moving quickly on land. [more]

Idiornithidae

[more]

Laornithidae

[more]

Mesitornithidae

The mesites (Mesitornithidae) are a of birds of uncertain affinities. They are smallish, near flightless birds endemic to Madagascar. Generally brownish with paler undersides, they are of somewhat pheasant-like appearance and were initially placed with the Galliformes. Most commonly, they are placed in the Gruiformes (cranes, rails and allies), but this has been disputed in more recent times. [more]

Messelornithidae

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Mestiornithidae

[more]

Otidae

Bustards are large terrestrial mainly associated with dry open country and steppes in the Old World. They make up the family Otididae (formerly known as Otidae). They were renowned by the ancient Arabs for being unnaturally stupid. [more]

Otididae

Bustards are large terrestrial mainly associated with dry open country and steppes in the Old World. They make up the family Otididae (formerly known as Otidae). They were renowned by the ancient Arabs for being unnaturally stupid. [more]

Phororhacidae

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Psilopteridae

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Psophiidae

The trumpeters are a small family of restricted to the forests of the Amazon and Orinoco basins in South America. They are named for the trumpeting or cackling threat call of the males. The three species resemble chickens in size; they measure 45 to 52 centimeters (18 to 20 inches) long and weigh 1 to 1.5 kilograms (2.2 to 3.3 pounds). They are dumpy birds with long necks and legs and curved bills and a hunched posture. Their heads are small, but their eyes are relatively large, making them look "good-natured". The plumage is soft, resembling fur or velvet on the head and neck. It is mostly black, with purple, green, or bronze iridescence, particularly on the wing coverts and the lower neck. The secondary and tertial flight feathers are white, gray, or greenish to black, and hairlike, falling over the lower back, which is the same color. These colors give the three species their names. [more]

Rallidae

The rails, or Rallidae, are a large family of small to medium-sized birds. The family exhibits considerable diversity and the family also includes the crakes, coots, and gallinules. Many species are associated with wetlands, although the family is found in every terrestrial habitat except dry deserts, polar regions and alpine areas above the snow line. [more]

Rhynchocetidae

[more]

Rhynochetidae

The Kagu (: ), Rhynochetos jubatus, is a long-legged blue-greyish bird endemic to the dense mountain forests of New Caledonia. It is the only surviving member of the family Rhynochetidae, although a second, larger species of the genus Rhynochetos, the Lowland Kagu Rhynochetos orarius, has been described from Holocene subfossil remains. It is almost flightless, and builds a ground nest of sticks, laying a single egg. It has proved vulnerable to introduced rats and cats, and is threatened with extinction. The remote habitat and rarity of this species mean that little is known of its habits. [more]

Songzidae

[more]

More info about the Family Songzidae may be found here.

References

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Sources

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Last Revised: November 19, 2008