Pygostyle

Source: Wikipedia, the free encyclopedia.
Pigeon
skeleton with "plowshare"-type pygostyle (number 17)
Confuciusornis sanctus
with "rod"-type pygostyle and the two central tail feathers

Pygostyle describes a skeletal condition in which the final few

preen oil
.

Evolution

Pygostyles probably began to evolve very early in the Cretaceous period, perhaps 140 – 130 million years ago. The earliest known species to have evolved a pygostyle were members of the Confuciusornithidae.[citation needed] The structure provided an evolutionary advantage, as a completely mobile tail as found in species such as Archaeopteryx is detrimental to its use for flight control. Modern birds still develop longer caudal vertebrae in their embryonic state, which later fuse to form a pygostyle.

There are two main types of pygostyle:[

downy fuzz and sometimes 2–4 central "streamers" such as those found in some specimens of Confuciusornis or in Paraprotopteryx.[1]

By contrast, the function of the pygostyle in the terrestrial Nomingia is not known. It is notable however that its older relative Caudipteryx had no pygostyle but a "fan" of symmetrical feathers which were probably used in social display. Perhaps such ornaments were widespread in Caenagnathoidea and their relatives, and ultimately the oviraptorosaurian pygostyle evolved to help support them. The related Similicaudipteryx, described in 2008, also had a rod-like pygostyle, associated with a fan of tail feathers.[2]

Yixianornis grabaui
, one of the oldest known species with a pygostyle like that in living birds

The other pygostyle type is

Hongshanornis longicresta.[3]

As evidenced by the oviraptorosaurian cases, the pygostyle evolved at least twice, and rod-shaped pygostyles seem to have evolved several times, in association with shortening of the tail but not necessarily with a retractable fan of tail feathers. In other words, the pygostyles of oviraptorosaurs and Confuciusornis were likely weight-saving measures, and the specialized "true" pygostyles of ornithurans were adapted from these later to improve flight performance.[1]

The bird

apomorphy
of a short tail bearing an avian pygostyle.

Etymology

"Pygostyle" is formed from Ancient Greek words, literally meaning "rump pillar".

The insulting equation of the pygostyle with the noses of dignitaries dates back to 18th century Britain where pope's nose first appears (in 1786). The form parson's nose appears much later, dated to 1839. The usage is somewhat dependent on either a Catholic or Protestant viewpoint.[5]

The forms bishop's nose and sultan's nose are 20th century variants.

As food

Turkey tail or turkey butt has an international exportation market in places such as Micronesia, Samoa, and Ghana. The turkey tail is commonly exported from America because it is considered unhealthy and cut off the normal turkey.[6] After World War II, cheap imported turkey tails became popular in Samoa. Because the cut has a very high fat content, it was banned from 2007 to 2013 to combat obesity, only allowed back when Samoa joined the World Trade Organization. The meat is otherwise used in pet food.[7]

Footnotes

References