Postnatal heterochrony of the masticatory apparatus in Cebus apella and Cebus albifrons
1992; Elsevier BV; Volume: 23; Issue: 3 Linguagem: Inglês
10.1016/s0047-2484(05)80003-x
ISSN1095-8606
Autores Tópico(s)Wildlife Ecology and Conservation
ResumoSpecies of the genus Cebus have been characterized as omnivorous, although Cebus apella differs significantly from the other Cebus species in its ability to routinely consume hard fruits and nuts. Hard-object feeding behavior in C. apella is reflected in a suite of craniomandibular features that are related to the generation and dissipation of higher masticatory stresses. This study examines the biomechanical differences between C. apella and Cebus albifrons, a species that does not exploit hard foods, by considering the ontogenetic sources of anatomical differences among adults. When adult forms are compared, C. apella are found to have greater relative depth and thickness of the corpus at M1 and greater relative thickness at the symphysis. In addition, the corporal and symphyseal cross-sections are absolutely larger. This overall pattern is consistent with the expectation of a need for increased resistance to parasagittal bending and twisting stresses in the corpus, increased resistance to wishboning stresses in the symphysis and greater resistance to shear stresses in both the corpus and symphysis. When patterns of postnatal growth are compared, it is found that there are few differences in growth trajectories, as indicated by similarity in regression line slopes. Instead, most of the biomechanical differences that distinguish adults are present early in postnatal life, as indicated by differences in regression line elevations. It is concluded that the modifications for hard-object feeding seen in C. apella adults are most probably the result of selection on prenatal growth processes.
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