Quadrate bone

Quadrate bone

The quadrate bone is part of a skull in most tetrapods, including amphibians, sauropsids (reptiles, inclused birds) and early synapsids. In these animals it connects to the quadratojugal and squamosal in the skull, and forms part of the jaw joint (the other part is the articular bone at the rear end of the lower jaw).

In snakes, the quadrate bone has become elongated and very mobile, and contributes greatly to their ability to swallow very large prey items.

In mammals the articular and quadrate bones have migrated to the middle ear and are known as the malleus and incus. In fact paleontologists regard this modification as the defining characteristic of mammals. [cite web | url=http://www.palaeos.com/Vertebrates/Units/Unit420/420.000.html | title=Mammaliformes: Overview - Palaeos]

References

External links

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* [http://campus.murraystate.edu/academic/faculty/terry.derting/anatomyatlas/snapturtskullamy-becky.html Image at murraystate.edu]


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  • Quadrate bone — Quadrate Quad rate, a. [L. quadratus squared, p. p. of quadrare to make four cornered, to make square, to square, to fit, suit, from quadrus square, quattuor four. See {Quadrant}, and cf. {Quadrat}, {Quarry} an arrow, {Square}.] 1. Having four… …   The Collaborative International Dictionary of English

  • quadrate bone — quadrate bone, one of the pair of bones in birds, fishes, amphibians, and reptiles that joins the lower jaw to the skull …   Useful english dictionary

  • Quadrate — Quad rate, a. [L. quadratus squared, p. p. of quadrare to make four cornered, to make square, to square, to fit, suit, from quadrus square, quattuor four. See {Quadrant}, and cf. {Quadrat}, {Quarry} an arrow, {Square}.] 1. Having four equal sides …   The Collaborative International Dictionary of English

  • quadrate — [kwä′drit, kwä′drāt΄; ] for v. [, kwä′drāt΄] adj. [ME < L quadratus, pp. of quadrare, to make square < quadrus, a square < quattuor,FOUR] 1. square or nearly square; rectangular 2. Zool. designating a bone or cartilage of the skull in… …   English World dictionary

  • Quadrate — Quad rate, n. [L. quadratum. See {Quadrate}, a.] 1. (Geom.) A plane surface with four equal sides and four right angles; a square; hence, figuratively, anything having the outline of a square. [1913 Webster] At which command, the powers militant… …   The Collaborative International Dictionary of English

  • Quadrate — may refer to:* Quadrate bone * Quadrate (heraldry) …   Wikipedia

  • quadrate — adj., n., & v. adj. esp. Anat. & Zool. square or rectangular (quadrate bone; quadrate muscle). n. 1 a quadrate bone or muscle. 2 a rectangular object. v. 1 tr. make square. 2 intr. & tr. (often foll. by with) conform or make conform. Etymology:… …   Useful english dictionary

  • quadrate — noun kwɒdrət (also quadrate bone) Zoology a squarish bone in the skull of a bird or reptile, with which the jaw articulates. adjective kwɒdrət roughly square or rectangular. verb kwɒ dreɪt, kwɒdreɪt (usu. quadrate with) archaic conform. Origin ME …   English new terms dictionary

  • quadrate — quad·rate || kwÉ‘drÉ™t , reɪt / kwÉ’d n. square, rectangular; item shaped like a square or rectangle; bone between the base of the skull and lower jaw v. make square; adapt, suit, fit; make agree, make correspond adj. square, rectangular;… …   English contemporary dictionary

  • quadrate — I. adjective Etymology: Middle English, from Latin quadratus, past participle of quadrare to make square, fit, from quadrum square; akin to Latin quattuor four Date: 14th century 1. being square or approximately square 2. of a heraldic cross… …   New Collegiate Dictionary

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