''Panraogallus'' is an

extinct Extinction is the termination of a kind of organism or of a group of kinds (taxon), usually a species. The moment of extinction is generally considered to be the death of the last individual of the species, although the capacity to breed and ...

genus of

phasianid The Phasianidae are a family of heavy, ground-living birds, which includes pheasants, partridges, junglefowl, chickens, turkeys, Old World quail, and peafowl. The family includes many of the most popular gamebirds. The family is a large one and i ...

bird (the family that contains pheasants and their relatives) from the

Late Miocene The Late Miocene (also known as Upper Miocene) is a sub-epoch of the Miocene epoch (geology), Epoch made up of two faunal stage, stages. The Tortonian and Messinian stages comprise the Late Miocene sub-epoch, which lasted from 11.63 Ma (million ye ...

of what is now China. The

holotype specimen A holotype is a single physical example (or illustration) of an organism, known to have been used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of several ...

was discovered in the Liushu Formation near the Zhuangkeji Township in Guanghe County,

Gansu Province Gansu (, ; alternately romanized as Kansu) is a province in Northwest China. Its capital and largest city is Lanzhou, in the southeast part of the province. The seventh-largest administrative district by area at , Gansu lies between the Tibeta ...

. The specimen consists of an almost complete skeleton of a young adult (perhaps a male, since it appears to have had a spur), though part of the skull and the neck vertebrae were reconstructed in plaster before the specimen was acquired by the Hezheng Paleozoological Museum. The specimen also preserves an elongated, coiled

trachea The trachea, also known as the windpipe, is a Cartilage, cartilaginous tube that connects the larynx to the bronchi of the lungs, allowing the passage of air, and so is present in almost all air-breathing animals with lungs. The trachea extends ...

(or windpipe), the oldest known bird fossil with such a structure. The specimen was made the basis of the new genus and species ''Panraogallus hezhengensis'' by the Chinese palaeontologist Zhihen Li and colleagues in 2018. The generic name is the

pinyin Hanyu Pinyin (), often shortened to just pinyin, is the official romanization system for Standard Mandarin Chinese in China, and to some extent, in Singapore and Malaysia. It is often used to teach Mandarin, normally written in Chinese for ...

of the

Chinese characters Chinese characters () are logograms developed for the writing of Chinese. In addition, they have been adapted to write other East Asian languages, and remain a key component of the Japanese writing system where they are known as ''kanji' ...

for "coiling" and Latin for "chicken", which refers to the elongated trachea; "coiled chicken" in full. The

specific name Specific name may refer to: * in Database management systems, a system-assigned name that is unique within a particular database In taxonomy, either of these two meanings, each with its own set of rules: * Specific name (botany), the two-part (bino ...

refers to the Hezheng area, where abundant specimens of this bird have been found. Panraogallus tracheal loop

Within Phasianidae, ''Panraogallus'' was found to be most closely related to the extant genus ''

Perdix ''Perdix'' is a genus of Galliform gamebirds known collectively as the 'true partridges'. These birds are unrelated to the subtropical species that have been named after the partridge due to similar size and morphology. Taxonomy The genus ''Pe ...

'' and members of the subfamilies Phasianinae, Tetraoninae, and

Meleagridinae Grouse are a group of birds from the order Galliformes, in the family Phasianidae. Grouse are presently assigned to the tribe Tetraonini (formerly the subfamily Tetraoninae and the family Tetraonidae), a classification supported by mitochond ...

. The elongation of the trachea is related to vocal modification, and has happened independently many times among birds, while ''Panraogallus'' is the first known pheasant with such an adaptation. The trachea of ''Panraogallus'' appears to have coiled twice outside its chest, and may have coiled back towards the chest, before going up to the chest cavity again where it attached to the lungs. The presence of this feature in ''Panraogallus'' indicates it has evolved more than one time independently within

Galliformes Galliformes is an order of heavy-bodied ground-feeding birds that includes turkeys, chickens, quail, and other landfowl. Gallinaceous birds, as they are called, are important in their ecosystems as seed dispersers and predators, and are often ...

, and does not appear to correlate with whether a galliform bird lived in open or closed habitat. Two extant phasianids are known with an elongated trachea, the

western capercaillie The western capercaillie (''Tetrao urogallus''), also known as the Eurasian capercaillie, wood grouse, heather cock, cock-of-the-woods, or simply capercaillie , is a heavy member of the grouse family and the largest of all extant grouse species. ...

and the

rock ptarmigan The rock ptarmigan (''Lagopus muta'') is a medium-sized game bird in the grouse family. It is known simply as the ptarmigan in the UK. It is the official bird for the Canadian territory of Nunavut, where it is known as the ''aqiggiq'' (ᐊᕿ� ...

. The evolution of a tracheal loop has been proposed to help with "size exaggeration", where smaller birds can produce bigger sounds for signalling and communication. The coiled trachea of ''Panraogallus'' was possibly longer than its body, and it probably produced sounds with a lower frequency and with reduced harmonics, compared to pheasants of a similar size. Previously, other functions have been proposed for the presence of an elongated trachea, such as

thermoregulation Thermoregulation is the ability of an organism to keep its body temperature within certain boundaries, even when the surrounding temperature is very different. A thermoconforming organism, by contrast, simply adopts the surrounding temperature ...

, but these are considered unlikely today. Since some features of the fossil are associated with

sexual dimorphism Sexual dimorphism is the condition where the sexes of the same animal and/or plant species exhibit different morphological characteristics, particularly characteristics not directly involved in reproduction. The condition occurs in most ani ...

, both the morphology and mechanism for vocalisation in ''Panraogallus'' may have evolved through

Sexual selection Sexual selection is a mode of natural selection in which members of one biological sex mate choice, choose mates of the other sex to mating, mate with (intersexual selection), and compete with members of the same sex for access to members of t ...

. The avifauna known from the Miocene deposits of Gansu Province also includes an extinct kestrel, an

ostrich Ostriches are large flightless birds of the genus ''Struthio'' in the order Struthioniformes, part of the infra-class Palaeognathae, a diverse group of flightless birds also known as ratites that includes the emus, rheas, and kiwis. There are ...

, and Old World vultures. Other animals include rhinoceroses and three-toed horses.

References

{{Taxonbar, from=Q60775785 Galliformes Fossil taxa described in 2018