Three-dimensional analysis of mandibular morphology inOtolemur

Burrows, Anne M.; Smith, Timothy D.

doi:10.1002/ajpa.20183

Cited by 16 publications

(11 citation statements)

References 54 publications

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“…Thus, for a given skull size, these two galago genera possess relatively lower temporomandibular joints (TMJs) and smaller gonial regions. Remarkably, this mirrors observations regarding reduction of the ascending ramus and a low TMJ relative to the occlusal plane in galagid, cheirogaleid and callitrichine exudativores [Vinyard et al, 2003;Viguier, 2004;contra Dumont, 1997;Burrows and Smith, 2005]. Holding other factors constant, particularly jaw adductor in-lever arm length, such a configuration enables increased gape by reducing the amount of elongation of jaw adductor muscle fibers [Herring and Herring, 1974;Greaves, 1995].…”

supporting

confidence: 65%

Allometry and Evolution in the Galago Skull

Ravosa¹,

Daniel²,

Costley³

2010

IJFP

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To probe the ontogenetic bases of morphological diversity across galagos, we performed the first clade-wide analyses of growth allometries in 564 adult and non-adult crania from 12 galagid taxa. In addition to evaluating if variation in galago skull form results from the differential extension/truncation of common ontogenetic patterns, scaling trajectories were employed as a criterion of subtraction to identify putative morphological adaptations in the feeding complex. A pervasive pattern of ontogenetic scaling is observed for facial dimensions across galagids, with 2 genera also sharing relative growth trajectories for masticatory proportions (Galago, Galagoides). As the facial growth series and adult data are largely coincidental, interspecific variation may result from character displacement and consequent selection for size differentiation among sister taxa. Derived configurations of the jaw joint and jaw muscle mechanical advantage in Otolemur and Euoticus appear to facilitate increased gape during scraping behaviors. Differences in aspects of masticatory growth and form characterizing these 2 genera highlight selection to uncouple shared ontogenetic patterns, which occurred via transpositions that retained ancestral scaling patterns. Due to the lack of increased robusticity of load-resisting mandibular elements in Otolemur and Euoticus, there is little evidence to suggest that exudativory in galagos results in correspondingly higher masticatory stresses.

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supporting

confidence: 65%

Allometry and Evolution in the Galago Skull

Ravosa¹,

Daniel²,

Costley³

2010

IJFP

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“…Galagonids show a less-striking, but similar pattern. The largest genus, Otolemur, also exhibits relatively low-condyle heights and feeds extensively on exudates (Williams et al, 2002;Burrows and Smith, 2005).…”

Section: Strepsirrhinesmentioning

confidence: 99%

An interspecific analysis of relative jaw‐joint height in primates

Armfield

Vinyard

2010

American J Phys Anthropol

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Jaw-joint height (JJH) above the occlusal plane is thought to be influenced by cranial base angle (CBA) and facial angulation during growth. To better understand how JJH relates to midline craniofacial form, we test the hypothesis that relative increases in JJH are correlated with increasing CBA flexion and facial kyphosis (i.e., ventral bending) across primates. We compared JJH above the occlusal plane to CBA and the angle of facial kyphosis (AFK) across adults from 82 species. JJH scales with positive allometry relative to a skull geometric mean in anthropoids and most likely strepsirrhines. Anthropoid regressions for JJH are elevated above strepsirrhines, whereas catarrhines exhibit a higher slope than platyrrhines. Semipartial correlations between relative JJH and both CBA and AFK show no association across a small strepsirrhine sample, limited associations among catarrhines and anthropoids, but strong correlations in platyrrhines. Contrary to our hypothesis, however, increases in relative JJH are correlated with relatively less flexed basicrania and more airorhynch faces (i.e., reduced ventral bending) in platyrrhines. The mosaic pattern of relationships involving JJH across primate clades points to multiple influences on JJH across primates. In clades showing little association with basicranial and facial angles, such as strepsirrhines, the potential morphological independence of JJH may facilitate a relative freedom for evolutionary changes related to masticatory function. Finally, failure to associate relative JJH and basicranial flexion in most clades suggests that the relatively taller JJH and more flexed basicrania of anthropoids compared to strepsirrhines may have evolved as an isolated event during the origin of anthropoids.

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“…Although much has been learned about mastication in greater galagos from in vivo research, we are just beginning to understand the variation in jaw form and function among members of the Galagidae [e.g., Burrows & Smith, 2005;Ravosa, 2005;Vinyard et al, 2003;Williams et al, 2002]. To date, interspecific analyses have compared skull shapes, but no one has examined whether (and if so, how) covariance structure differs among masticatory apparatus (MA) features across galagos.…”

Section: Introductionmentioning

confidence: 99%

Interspecific analysis of covariance structure in the masticatory apparatus of galagos

Vinyard

2006

American J Primatol

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The primate masticatory apparatus (MA) is a functionally integrated set of features, each of which performs important functions in biting, ingestive, and chewing behaviors. A comparison of morphological covariance structure among species for these MA features will help us to further understand the evolutionary history of this region. In this exploratory analysis, the covariance structure of the MA is compared across seven galago species to investigate 1) whether there are differences in covariance structure in this region, and 2) if so, how has this covariation changed with respect to size, MA form, diet, and/or phylogeny? Ten measurements of the MA functionally related to bite force production and load resistance were obtained from 218 adults of seven galago species. Correlation matrices were generated for these 10 dimensions and compared among species via matrix correlations and Mantel tests. Subsequently, pairwise covariance disparity in the MA was estimated as a measure of difference in covariance structure between species. Covariance disparity estimates were correlated with pairwise distances related to differences in body size, MA size and shape, genetic distance (based on cytochrome-b sequences) and percentage of dietary foods to determine whether one or more of these factors is linked to differences in covariance structure. Galagos differ in MA covariance structure. Body size appears to be a major factor correlated with differences in covariance structure among galagos. The largest galago species, Otolemur crassicaudatus, exhibits large differences in body mass and covariance structure relative to other galagos, and thus plays a primary role in creating this association. MA size and shape do not correlate with covariance structure when body mass is held constant. Diet also shows no association. Genetic distance is significantly negatively correlated with covariance disparity when body mass is held constant, but this correlation appears to be a function of the small body size and large genetic distance for Galagoides demidoff. These exploratory results indicate that changing body size may have been a key factor in the evolution of the galago MA.

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Three-dimensional analysis of mandibular morphology inOtolemur

Cited by 16 publications

References 54 publications

Allometry and Evolution in the Galago Skull

Allometry and Evolution in the Galago Skull

An interspecific analysis of relative jaw‐joint height in primates

Interspecific analysis of covariance structure in the masticatory apparatus of galagos

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