Trabecular Bone Structure in the Mandibular Condyles of Gouging and Nongouging Platyrrhine Primates
Anthropology; architecture; biomechanics; bone; callithrix-jacchus; callitrichids; cancellous; cortical bone; elastic principal directions; Evolutionary Biology; femoral-head; fossil record; iterative selection method; jaw functional morphology; marmosets; mechanical properties; tamarins; temporomandibular-joint
The relationship between mandibular form and biomechanical function is a topic of significant interest to morphologists and paleontologists alike. Several previous studies have examined the morphology of the mandible in gouging and nongouging primates as a means of understanding the anatomical correlates of this feeding behavior. The goal of the current study was to quantify the trabecular bone structure of the mandibular condyle of gouging and nongouging primates to assess the functional morphology of the jaw in these animals. High-resolution computed tomography scan data were collected from the mandibles of five adult common marmosets (Callithrix jacchus), saddle-back tamarins (Saguinus fuscicollis), and squirrel monkeys (Saimiri sciureus), respectively, and various three-dimensional morphometric parameters were measured from the condylar trabecular bone. No significant differences were found among the taxa for most trabecular bone structural features. Importantly, no mechanically significant parameters, such as bone volume fraction and degree of anisotropy, were found to vary significantly between gouging and nongouging primates. The lack of significant differences in mechanically relevant structural parameters among these three platyrrhine taxa may suggest that gouging as a habitual dietary behavior does not involve significantly higher loads on the mandibular condyle than other masticatory behaviors. Alternatively, the similarities in trabecular architecture across these three taxa may indicate that trabecular bone is relatively unimportant mechanically in the condyle of these primates and therefore is functionally uninformative. Am J Phys Anthropol 141:583-593, 2010. (C) 2009 Wiley-Liss, Inc.
Ryan T M; Colbert M; Ketcham R A; Vinyard C J
American Journal of Physical Anthropology
2010
2010-04
Journal Article
<a href="http://doi.org/10.1002/ajpa.21178" target="_blank" rel="noreferrer noopener">10.1002/ajpa.21178</a>
The Functional Correlates of Jaw-Muscle Fiber Architecture in Tree-Gouging and Nongouging Callitrichid Monkeys
Anthropology; arboreal guenons; bite force; callitrichids; cross-sectional area; Evolutionary Biology; Exudativory; Fiber length; gape; internal architecture; jaw; marmosets; masseter muscle; morphology; physiologic cross-sectional area; rabbit oryctolagus-cuniculus; sarcomere-length; skeletal-muscle; tamarins; temporalis muscle; world monkeys
Common (Callithrix jacchus) and pygmy (Cebuella pygmaea) marmosets and cotton-top tamarins (Saguinus oedipus) share broadly similar diets of fruits, insects, and tree exudates. Marmosets, however, differ from tamarins in actively gouging trees with their anterior dentition to elicit tree exudates flow. Tree gouging in common marmosets involves the generation of relatively wide jaw gapes, but not necessarily relatively large bite forces. We compared fiber architecture of the masseter and temporalis muscles in C. jacchus (N = 18), C. pygmaea (N = 5), and S. oedipus (N = 13). We tested the hypothesis that tree-gouging marmosets would exhibit relatively longer fibers and other architectural variables that facilitate muscle stretch, As an architectural trade-off between maximizing muscle excursion/contraction velocity and muscle force, we also tested the hypothesis that marmosets would exhibit relatively less pinnate fibers, smaller physiologic cross-sectional areas (PCSA), and lower priority indices (I) for force. As predicted, marmosets display relatively longer-fibered muscles, a higher ratio of fiber length to muscle mass, and a relatively greater potential excursion of the distal tendon attachments, all of which favor muscle stretch. Marmosets further display relatively smaller PCSAs and other features that reflect a reduced capacity for force generation. The longer fibers and attendant higher contraction velocities likely facilitate the production of relatively wide jaw gapes and the capacity to generate more power from their jaw muscles during gouging. The observed functional trade-off between muscle excursion/contraction velocity and muscle force suggests that primate jaw-muscle architecture reflects evolutionary changes related to jaw movements as one of a number of functional demands imposed on the masticatory apparatus. Am J Phys Anthropol 139:353-367, 2009. (C) 2009 Wiley-Liss, Inc.
Taylor A B; Eng C M; Anapol F C; Vinyard C J
American Journal of Physical Anthropology
2009
2009-07
Journal Article
<a href="http://doi.org/10.1002/ajpa.20991" target="_blank" rel="noreferrer noopener">10.1002/ajpa.20991</a>
Spatial Distribution and Exploitation of Trees Gouged by Common Marmosets (Callithrix jacchus)
alouatta-palliata; callitrichids; Exudativory; food resource distribution; GIS; group-size; home-range use; howler monkeys; Intergroup competition; japanese macaques; monkeys erythrocebus-patas; patch size; Renewable; Resource distribution; resources; social-organization; territorial defense; Zoology
Resource distribution shapes many aspects of primate behavioral ecology. Though the spatial patterning of fruits, leaves, and insects has been explored among primate foods, comparatively less is known about exudate distributions. Tree exudates are a renewable resource, provide long-term evidence of exploitation, and may be selectively exploited to manipulate spatial distribution. We assessed the spatial patterning of trees gouged by common marmosets (Callithrix jacchus) to determine if they exhibit a uniform, random, or clumped distribution. We also asked whether marmosets selectively gouge trees in home range centers, which may afford them exclusive access to exudates. We explored whether spatial or physical characteristics of trees predict how intensely gouged trees were exploited. The mean nearest neighbor distance of gouged trees was significantly closer than expected for a random distribution and Ripley's K-function showed that gouged trees were clumped across all spatial scales in our study area. Clumping may enable marmosets to reduce day and home ranges and facilitate repeated gouging of trees. Gouged trees were not closer to marmosets' home range centers than peripheries, nor were centrally located trees more intensely gouged. Increased gouging intensity was associated with larger tree circumferences, although this effect was primarily driven by interspecific differences in circumference. Although marmosets may benefit from exploiting clumped exudates, they do not concentrate gouging in areas where they are more likely to gain exclusive access. Species-specific tree characteristics such as exudate quality and/or bark properties may play a larger role in determining gouging patterns than intergroup feeding competition.
Thompson C L; Robl N J; Melo L C; Valena-Montenegro M M; Valle Y B M; de Oliveira M A B; Vinyard C J
International Journal of Primatology
2013
2013-02
Journal Article
<a href="http://doi.org/10.1007/s10764-012-9647-7" target="_blank" rel="noreferrer noopener">10.1007/s10764-012-9647-7</a>