Locomotor behavior and skeletal morphology of two sympatric pitheciine monkeys, Pithecia pithecia and Chiropotes satanas

Abstract

Field observations of two sympatric pitheciine species reveal that the positional repertoire of the white-faced saki, Pithecia pithecia, is dominated by leaping behaviors, whereas the bearded saki, Chiropotes satanas, is predominantly quadrupedal. Examination and comparison of the postcranial skeletal morphologies and limb proportions of these species display numerous features associated with their respective locomotor behaviors. These observations accord with associations found in other primate and mammalian groups and with predictions based on theoretical and experimental biomechanics. Preliminary observations of the skeletal morphology of Cacajao calvus demonstrate a marked similarity to that of Chiropotes. The fossil platyrrhine Cebupithecia sarmientoi displays greater similarity to Pithecia, suggesting that its positional repertoire also included significant leaping and clinging behaviors.

Hind limb of the <i>Nacholapithecus kerioi</i> holotype and implications for its positional behavior

“…A trapezoidal patellar surface with a proximally extended lateral side suggests that the contraction of the vastus lateralis was proportionally greater (Fleagle and Meldrum, 1988) and accords with a flexed and abducted knee, a posture suitable for a medium-sized mammal to keep balance while perched on a branch. While this is the case for in P. nyanzae (Figure 3e), the patellar surface in N. kerioi is square-shaped.…”

“…An asymmetrically wider medial condyle is suggestive of emphasized loading of the medial side of the knee (Rafferty and Ruff, 1994;Mader et al, 2002). Thus, condylar width asymmetry in primates has been interpreted as an emphasis of thigh abduction in relation to arboreal quadrupedalism and/or climbing (Tardieu, 1981;Jungers and Susman, 1984;Fleagle, 1977;Fleagle and Meldrum, 1988;MacLatchy et al, 2000;Mader et al, 2002). If the knee of N. kerioi experienced habitual abduction, then condylar width asymmetry would have been accentuated similarly to Proconsul and M. bishopi ( Figure 3e, Table 2).…”

Postcranial Remains of the Extinct Monkeys of the Greater Antilles, with Evidence for Semiterrestriality in Paralouatta1

“…In many other regards they are similar, such as in (1) the relative size and conformation of proximal and distal articular surfaces, (2) the presence of the entepicondylar foramen, (3) the size and disposition of the tubercles, and (4) the moderate development of the brachialis flange. Several of these contrasts, which hold for other similar-sized platyrrhines such as Chiropotes satanas and Pithecia pithecia (Fleagle and Meldrum, 1988), are discussed further under Functional Considerations.…”

Répertoire postural du singe <i>Cercopithecus nictitans stampflii</i>, dans le Parc National de Taï (Côte-d\'Ivoire)

“…Cependant, la plupart des études antérieures se sont le plus souvent intéressées au comportement de locomotion. En effet, celui ci exerce une grande influence sur l'anatomie des primates et permet la reconstruction du comportement des primates fossiles (Fleagle & Meldrum, 1988 ;Duncan et al, 1994 ;Nkatsukasa et al, 1997). Cependant, il est évident que tous les primates passent la majeure partie du temps engagés dans différentes postures que dans les activités de locomotion.…”