Glenohumeral joint surface characters and its relation to forelimb suspensory behavior in three ateline primates, Ateles, Lagothrix, and Alouatta

"Suspensory locomotion" is an expression that encompasses a series of specialized forms of locomotion that mainly orthograde primates use to achieve below-branch traveling. It implies a number of features in the entire body associated with the use of the forelimb in overhead positions. The glenohumeral joint is one of the main joints involved in effective suspensory locomotion, being subject to a delicate balance between the high degree of mobility and stabilization needed to successfully engage in suspensory behaviors. Here, we present a 3D geometric morphometric study that explores the form of the proximal humerus of six orthograde and semi-orthograde genera (Hylobates, Pongo, Pan, Gorilla, Ateles, and Lagothrix) and a pronograde genus, Colobus, to determine to what extent suspensory locomotor requirements are driving the shape of this epiphysis. Results show the presence of a morphocline related to degree of suspension in the shape of the articular surface, with highly suspensory taxa (i.e., Hylobates) exhibiting particular morphological traits at the articular surface that provide a greater range of circumduction. The placement and orientation of the rotator cuff muscles' insertion sites on the tubercles appear associated with the divergent forces operating at the joint in quadrupedal or above-head use of the hand.

Section: Articular Surfacementioning

confidence: 88%

“…The mountain gorilla spends a more significant amount of time in brachiation: 3.6% [Crompton et al, 2010]. g Cant et al [2001], Kagaya [2007]. h Cant et al [2001], Kagaya [2007].…”

Section: The Independent Factorsmentioning

confidence: 99%

“…g Cant et al [2001], Kagaya [2007]. h Cant et al [2001], Kagaya [2007]. i Gebo & Chapman [1995], Mittermeier & Fleagle [1976], Rose [1974Rose [ , 1979.…”

Section: The Independent Factorsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Shape analysis of the proximal humerus in orthograde and semi‐orthograde primates: Correlates of suspensory behavior

Arias-Martorell

Tallman

Potau

et al. 2014

Feeding and Resting Postures of Wild Northern Muriquis (Brachyteles hypoxanthus)

Iurck

Nowak

Costa

et al. 2012

Increased body size in Brachyteles has been regarded as an important evolutionary adaptation that allowed a greater reliance on leaves compared to other more frugivorous Atelidae, but its association with muriqui positional behavior and substrate use is still unknown. Here, we present original data on the feeding and resting postures of the northern muriqui (Brachyteles hypoxanthus) and evaluate predictions about the relationships between body size, postural behavior, and substrate use derived from previously published data for other atelids (e.g. Alouatta, Ateles, and Lagothrix). The study was undertaken from August 2002 to July 2003 on a large group of well-habituated muriquis inhabiting the Reserva Particular do Patrimônio Natural - Felíciano Miguel Abdala in Minas Gerais, Brazil. Consistent with our predictions, we found that B. hypoxanthus was highly suspensory during postural feeding (60.9%) and commonly used tail-hind limb suspension/horizontal tripod (38.0%) or tail-forelimb/hind limb suspension (21.4%). However, although tail-suspensory postures permitted the muriquis to use the terminal canopy and small-sized substrates, these areas were also accessed via tail-assisted above-branch postural behaviors involving multiple substrates. Unexpectedly, tail-suspensory postures were found to be frequently associated with large substrates, tree trunks, and the understory. We suggest that Brachyteles' ability to access food resources from all areas of a feeding tree and from tree crowns at different canopy levels may account for their ability to efficiently exploit food resources in seasonal disturbed forest fragments of the Brazilian Atlantic Forest today.

Functional morphology of the douc langur (Pygathrix spp.) scapula

Bailey

Lad

Pampush

2017

Most colobine monkeys primarily move through their arboreal environment quadrupedally. Douc langurs (Pygathrix spp.), however, are regularly observed to use suspensory behaviors at the Endangered Primate Rescue Center (EPRC) in Northern Vietnam. Previous work has linked variation in scapular morphology to different modes of primate arboreal locomotion. Here we investigate whether the shape of the Pygathrix scapula resembles obligate brachiators (gibbons) or obligate arboreal quadrupeds (other cercopithecoids). Using a MicroScribe G2X 3D digitizer, the positions of 17 landmarks were recorded on 15 different species of nonhuman primates (n = 100) from three categories of locomotor behavior: brachiator, arboreal quadruped, and unknown (Pygathrix). All analyses were conducted in the R package geomorph. A Procrustes analysis uniformly scaled the shape data and placed specimens into the same morphospace. A Principal Component Analysis was used to examine scapular shape and a Procrustes ANOVA was conducted to test for shape difference in the scapulae. A pairwise analysis was used to compare the means of the locomotor categories and identify any statistically significant differences. A phylogenetically controlled Procrustes ANOVA was also conducted using a phylogeny from 10kTrees. Results show Pygathrix scapular morphology is significantly different from both arboreal colobine quadrupeds (p < 0.01) and hylobatid brachiators (p < 0.01). It does, however, share some features with each including a long vertebral border, like other cercopithecoids, and a more laterally projecting acromion process, like the hylobatids. The principal difference segregating Pygathrix from both the arboreal quadrupeds and the brachiators is the more medially placed superior angle. These nuanced morphological characteristics associated with suspensory behaviors may be useful for inferring suspensory locomotion in the primate fossil record.