Editing Quadrate bone

{{Short description|Skull bone}}
{{Other uses|Quadrate (disambiguation)}}
{{See also|Evolution of mammalian auditory ossicles}}
[[Image:Skull anapsida 1.svg|thumb|300px|A schematic of an [[anapsid]] skull showing the location of major dermal bones of the upper skull, including the quadrate bone (q).]]The '''quadrate''' bone is a [[skull]] bone in most [[tetrapods]], including [[amphibians]], [[sauropsids]] ([[reptiles]], [[birds]]), and early [[synapsids]].

In most tetrapods, the quadrate bone connects to the [[quadratojugal]] and [[squamosal]] bones in the skull, and forms upper part of the jaw joint. The lower jaw articulates at the [[articular]] bone, located at the rear end of the lower jaw. The quadrate bone forms the lower jaw articulation in all classes except mammals.<ref>{{Cite book|last=Romer, Alfred Sherwood, 1894-1973.|title=The vertebrate body : shorter version|date=1978|publisher=Saunders|others=Parsons, Thomas S. (Thomas Sturges), 1930-|isbn=0-7216-7682-0|edition=5th|location=Philadelphia|oclc=3345587}}</ref>

Evolutionarily, it is derived from  the hindmost part of the primitive cartilaginous upper jaw.

== Function in reptiles ==
[[File:Python Daudin, 1803.jpg|left|thumb|275x275px|An exploded python skull with disarticulated upper and lower jaws. The quadrate bone (c) is particularly elongated in snakes, to facilitate [[cranial kinesis]]. Courtesy of the Peabody Museum of Natural History, Division of Vertebrate Zoology, Yale University.]]In certain extinct reptiles, the variation and stability of the morphology of the quadrate bone has helped paleontologists in the species-level taxonomy and identification of mosasaur squamates <ref>DeBraga, M. and Carroll, R.L., 1993. The origin of mosasaurs as a model of macroevolutionary patterns and processes. In Evolutionary biology (pp. 245-322). Springer US.</ref> and [[Spinosauridae|spinosaurine]] dinosaurs.<ref>Hendrickx, C., Mateus O., & Buffetaut E. (2016).  Morphofunctional Analysis of the Quadrate of Spinosauridae (Dinosauria: Theropoda) and the Presence of Spinosaurus and a Second Spinosaurine Taxon in the Cenomanian of North Africa.. PLoS ONE. 11, e0144695., 01, Number 1: Public Library of Science</ref>

In some lizards and dinosaurs, the quadrate is articulated at both ends and movable.{{Citation needed|date=April 2020}} In snakes, the quadrate bone has become elongated and very mobile, and contributes greatly to their ability to swallow very large prey items.<ref>{{Cite journal|last1=Lee|first1=Michael S. Y.|last2=Bell|first2=Gorden L.|last3=Caldwell|first3=Michael W.|date=August 1999|title=The origin of snake feeding|url=https://www.nature.com/articles/23236|journal=Nature|language=en|volume=400|issue=6745|pages=655–659|doi=10.1038/23236|bibcode=1999Natur.400..655L |s2cid=4425886 |issn=1476-4687|url-access=subscription}}</ref>

== Function in mammals ==
In [[mammals]], the [[articular]] and quadrate bones have migrated to the [[middle ear]] and are known as the [[malleus]] and '''[[incus]]'''.<ref>{{Cite book|last=Homberger, Dominique G.|title=Vertebrate dissection|date=2004|publisher=Thomson Brooks/Cole|others=Walker, Warren F. (Warren Franklin), Walker, Warren F. (Warren Franklin).|isbn=0-03-022522-1|edition=9th|location=Belmont, CA|oclc=53074665}}</ref><ref>{{Cite journal|last1=Luo|first1=Zhexi|last2=Crompton|first2=Alfred W.|date=1994-09-07|title=Transformation of the quadrate (incus) through the transition from non-mammalian cynodonts to mammals|journal=Journal of Vertebrate Paleontology|volume=14|issue=3|pages=341–374|doi=10.1080/02724634.1994.10011564|issn=0272-4634}}</ref>  Along with the [[stapes]], which is [[Homology (biology)|homologous]] to some reptilian and amphibian [[Columella (auditory system)|columellae]], these are known as the [[ossicles]] and are a defining characteristic of mammals.

=== Development ===
In pig embryos, the mandible ossifies on the side of [[Meckel's cartilage]], while the posterior part of that cartilage is ossified into the incus. In later development, this portion detaches from the rest of the cartilage and migrates into the middle ear.<ref name="Scott">Scott 2000, Paragraph starting with "The original jaw bones changed also. [...] "</ref>

== References ==
{{reflist}}

==External links==
* {{cite web
 | url = http://campus.murraystate.edu/academic/faculty/terry.derting/anatomyatlas/snapturtskullamy-becky.html
 | title = Dorsal View Snapping Turtle Skull (Photo)
 | publisher = Murray State University
 | access-date = 5 January 2010
}}

{{Tetrapod osteology|S.}}

[[Category:Skull bones]]


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