Editing Quadrate bone (section)

{{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.