Jaw muscles of New World squirrels

Journal of Morphology
S S Ball, V Louise Roth

Abstract

The jaw, suprahyoid, and extrinsic tongue muscles are described for eight species of New World squirrels, spanning more than an order of magnitude in body mass. Anatomical differences are discussed in the light of body size, natural history, and phylogeny. The relative sizes of different muscles, their orientations, and the shapes and positions of their areas of attachment vary but show few trends in relation to body size. The anatomical differences are likewise not readily explained by the mechanical requirements of the animals' diets, which are similar. The most marked anatomical differences occur in Sciurillus (the pygmy tree squirrel), as well as those genera--Glaucomys (the flying squirrel) and Tamias (the chipmunk)--that are taxonomically most distinct from the tree squirrels. Sciurillus is noteworthy for its unusually small temporalis and an anterior deep masseter that is oriented to assist in retraction of the jaw. Tamias has a more vertically oriented temporalis and greater inclination in the anterior masseter muscles than the other squirrels, features that may be associated with its large diastema and relatively posteriorly situated cheek teeth, which in turn may relate to its having cheek pouches. Our results form a ...Continue Reading

References

May 1, 1975·Journal of Morphology·W A Weijs, R Dantuma
Nov 1, 1966·Biological Reviews of the Cambridge Philosophical Society·S J Gould
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Citations

May 4, 2004·Molecular Phylogenetics and Evolution·Matthew D HerronChristopher L Parkinson
Jul 12, 2011·Integrative and Comparative Biology·Robert E DruzinskyFrits L De Vree
Feb 28, 2009·Journal of Anatomy·Laura A B Wilson, Marcelo R Sánchez-Villagra
May 4, 2011·The Anatomical Record : Advances in Integrative Anatomy and Evolutionary Biology·Philip G Cox, Nathan Jeffery
Apr 24, 2013·Ecology and Evolution·Laura A B Wilson
Dec 6, 2016·Evolution; International Journal of Organic Evolution·Ana Paula A AssisGabriel Marroig
Jan 12, 2017·Evolution; International Journal of Organic Evolution·Miriam Leah ZelditchDonald L Swiderski
Nov 1, 1996·Journal of Morphology·R W Thorington, K Darrow
May 1, 1997·Journal of Morphology·W A Velhagen, V L Roth
Mar 31, 2004·Journal of Morphology·Kazuhiko Satoh, Fumihiko Iwaku

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