In most tetrapods, the quadrate bone connects to thequadratojugal andsquamosal bones in the skull, and forms upper part of the jaw joint. The lower jaw articulates at thearticular bone, located at the rear end of the lower jaw. The quadrate bone forms the lower jaw articulation in all classes except mammals.[1]
Evolutionarily, it is derived from the hindmost part of the primitive cartilaginous upper jaw.
An exploded python skull with disarticulated upper and lower jaws. The quadrate bone (c) is particularly elongated in snakes, to facilitatecranial 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[2] andspinosaurine dinosaurs.[3]
In some lizards and dinosaurs, the quadrate is articulated at both ends and movable.[citation needed] In snakes, the quadrate bone has become elongated and very mobile, and contributes greatly to their ability to swallow very large prey items.[4]
In pig embryos, the mandible ossifies on the side ofMeckel'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.[7]
^Romer, Alfred Sherwood, 1894-1973. (1978).The vertebrate body : shorter version. Parsons, Thomas S. (Thomas Sturges), 1930- (5th ed.). Philadelphia: Saunders.ISBN0-7216-7682-0.OCLC3345587.{{cite book}}: CS1 maint: multiple names: authors list (link) CS1 maint: numeric names: authors list (link)
^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.
^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
^Homberger, Dominique G. (2004).Vertebrate dissection. Walker, Warren F. (Warren Franklin), Walker, Warren F. (Warren Franklin). (9th ed.). Belmont, CA: Thomson Brooks/Cole.ISBN0-03-022522-1.OCLC53074665.
^Luo, Zhexi; Crompton, Alfred W. (1994-09-07). "Transformation of the quadrate (incus) through the transition from non-mammalian cynodonts to mammals".Journal of Vertebrate Paleontology.14 (3):341–374.doi:10.1080/02724634.1994.10011564.ISSN0272-4634.
^Scott 2000, Paragraph starting with "The original jaw bones changed also. [...] "
