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 early radiations of cetacea (Mammalia): Evolutionary pattern and developmental correlations
archaeocete; artiodactyls; development; Environmental Sciences & Ecology; evolution; Evolutionary Biology; feet; fossil record; India; locomotor evolution; marine mammal; middle eocene; origin; pakistan; Stenella attenuata; time; whales
The origin and early evolution of Cetacea (whales, dolphins, and porpoises) is one of the best examples of macroevolution as documented by fossils. Early whales are divided into six families that differ greatly in their habitats, which varied from land to freshwater, coastal waters, and fully marine. Early cetaceans lived in the Eocene (55-37 million years ago), and they show an enormous morphological diversity. Toward the end of the Eocene the modem cetacean body plan originated, and this body plan remained more or less the same in the subsequent evolution. It is possible that some aspects of this body plan are rooted in constraints that are dictated by cetacean embryologic development and controlled by genes that affect many organ systems at once. It may be possible to use a study of patterns of correlations among morphological traits to test hypotheses of developmental links among organ systems.
Thewissen J G M; Williams E M
Annual Review of Ecology and Systematics
2002
2002
Journal Article
<a href="http://doi.org/10.1146/annurev.ecolysis.33.020602.095426" target="_blank" rel="noreferrer noopener">10.1146/annurev.ecolysis.33.020602.095426</a>