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On the Jaw Mechanism of the Snail-Crushing Lizards, Dracaena Daudin 1802 (Reptilia, Lacertilia, Teiidae)

George H. Dalrymple
Journal of Herpetology
Vol. 13, No. 3 (Jul. 30, 1979), pp. 303-311
DOI: 10.2307/1563324
Stable URL: http://www.jstor.org/stable/1563324
Page Count: 9
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Since scans are not currently available to screen readers, please contact JSTOR User Support for access. We'll provide a PDF copy for your screen reader.
On the Jaw Mechanism of the Snail-Crushing Lizards, Dracaena Daudin 1802 (Reptilia, Lacertilia, Teiidae)
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Abstract

Modifications of the jaw mechanism of the lizard, Dracaena guianensis (family Teiidae), for durophagy (feeding upon hard-shelled foods) are described on the basis of comparisons with its close relative Tupinambis. There is an enlargement of sites for jaw muscle attachments and strengthening of palatal architecture for the crushing mode of feeding. The distinctively flared quadrate allows for enlargement of the Add. mand. externus muscle, resulting in improvement of the mechanical advantage of the muscle as well as reinforcement of the jaw articulation. Study of the dentition in relation to size reveals that enlarged and flattened teeth are present even in smaller lizards and are not the result of ontogenetic alteration. The state of the constrictor dorsalis muscles and the intracranial joints indicate that cranial kinetic motions may occur during feeding. These findings indicate the need for re-evaluation of theories of the adaptive significance of cranial kinesis in lizards.

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