Quadrate bone

Source: Wikipedia, the free encyclopedia.
For other uses, see Quadrate (disambiguation).
See also: Evolution of mammalian auditory ossicles
synapsids
.

In most tetrapods, the quadrate bone connects to 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.[1]

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

Function in reptiles

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 [2] and spinosaurine 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]

Function in mammals

In

articular and quadrate bones have migrated to the middle ear and are known as the malleus and incus.[5][6] Along with the stapes, which is homologous to some reptilian and amphibian 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.[7]

References

  1. OCLC 3345587.{{cite book}}: CS1 maint: multiple names: authors list (link) CS1 maint: numeric names: authors list (link
    )
  2. ^ 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.
  3. ^ 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
  4. S2CID 4425886
    .
  5. OCLC 53074665
    .
  6. ISSN 0272-4634
    .
  7. ^ Scott 2000, Paragraph starting with "The original jaw bones changed also. [...] "

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