Comparative Anatomical Analyses of the Forearm Muscles of Cebus libidinosus (Rylands et al. 2000): Manipulatory Behavior and Tool Use

The present study describes the flexor and extensor muscles in Cebus libidinosus' forearm and compares them with those from humans, chimpanzees and baboons. The data is presented in quantitative anatomical indices for similarity. The capuchin forearm muscles showed important similarities with chimpanzees and humans, particularly those that act on thumb motion and allow certain degree of independence from other hand structures, even though their configuration does not enable a true opposable thumb. The characteristics of Cebus' forearm muscles corroborate the evolutionary convergence towards an adaptive behavior (tool use) between Cebus genus and apes

Terrestrial behavior in titi monkeys (Callicebus, Cheracebus, and Plecturocebus) : potential correlates, patterns, and differences between genera

For arboreal primates, ground use may increase dispersal opportunities, tolerance to habitat change, access to ground-based resources, and resilience to human disturbances, and so has conservation implications. We collated published and unpublished data from 86 studies across 65 localities to assess titi monkey (Callicebinae) terrestriality. We examined whether the frequency of terrestrial activity correlated with study duration (a proxy for sampling effort), rainfall level (a proxy for food availability seasonality), and forest height (a proxy for vertical niche dimension). Terrestrial activity was recorded frequently for Callicebus and Plecturocebus spp., but rarely for Cheracebus spp. Terrestrial resting, anti-predator behavior, geophagy, and playing frequencies in Callicebus and Plecturocebus spp., but feeding and moving differed. Callicebus spp. often ate or searched for new leaves terrestrially. Plecturocebus spp. descended primarily to ingest terrestrial invertebrates and soil. Study duration correlated positively and rainfall level negatively with terrestrial activity. Though differences in sampling effort and methods limited comparisons and interpretation, overall, titi monkeys commonly engaged in a variety of terrestrial activities. Terrestrial behavior in Callicebus and Plecturocebus capacities may bolster resistance to habitat fragmentation. However, it is uncertain if the low frequency of terrestriality recorded for Cheracebus spp. is a genus-specific trait associated with a more basal phylogenetic position, or because studies of this genus occurred in pristine habitats. Observations of terrestrial behavior increased with increasing sampling effort and decreasing food availability. Overall, we found a high frequency of terrestrial behavior in titi monkeys, unlike that observed in other pitheciids

Reexamination of Statistical Methods for Comparative Anatomy: Examples of Its Application and Comparisons with Other Parametric and Nonparametric Statistics

Various statistical methods have been published for comparative anatomy. However, few studies compared parametric and nonparametric statistical methods. Moreover, some previous studies using statistical method for comparative anatomy (SMCA) proposed the formula for comparison of groups of anatomical structures (multiple structures) among different species. The present paper described the usage of SMCA and compared the results by SMCA with those by parametric test (t-test) and nonparametric analyses (cladistics) of anatomical data. In conclusion, the SMCA can offer a more exact and precise way to compare single and multiple anatomical structures across different species, which requires analyses of nominal features in comparative anatomy

A capuchin right hand.

<p>Dissection shows (arrow) the tendon of insertion of digit I long flexor muscle, (1) opponent muscle, and adductor muscle’s (2a) oblique head and (2b) transverse head. (bar = 2.8 cm).</p

Comparative Anatomy of the Hind Limb Vessels of the Bearded Capuchins (Sapajus libidinosus) with Apes, Baboons, and Cebus capucinus: With Comments on the Vessels' Role in Bipedalism

Capuchin monkeys are known to exhibit sporadic bipedalism while performing specific tasks, such as cracking nuts. The bipedal posture and locomotion cause an increase in the metabolic cost and therefore increased blood supply to lower limbs is necessary. Here, we present a detailed anatomical description of the capuchin arteries and veins of the pelvic limb of Sapajus libidinosus in comparison with other primates. The arterial pattern of the bearded capuchin hind limb is more similar to other quadrupedal Cebus species. Similarities were also found to the pattern observed in the quadruped Papio, which is probably due to a comparable pelvis and the presence of the tail. Sapajus' traits show fewer similarities when compared to great apes and modern humans. Moreover, the bearded capuchin showed unique patterns for the femoral and the short saphenous veins. Although this species switches easily from quadrupedal to bipedal postures, our results indicate that the bearded capuchin has no specific or differential features that support extended bipedal posture and locomotion. Thus, the explanation for the behavioral differences found among capuchin genera probably includes other aspects of their physiology

Photograph of the anterior aspect of forearm left of <i>C.l.</i>

<p>The arrow is indicating the tendon of flexor pollicis longus. 1) flexor digitorum profundus muscle and 2) flexor pollicis longus muscle. (bar = 0,7 cm).</p

Comparative analysis of the flexor deep muscles forearm among <i>C.l.</i>, human (<i>Homo</i>), chimpanzee (<i>Pan</i>) and baboon (<i>Papio</i>).

<p>Comparative analysis of the flexor deep muscles forearm among <i>C.l.</i>, human (<i>Homo</i>), chimpanzee (<i>Pan</i>) and baboon (<i>Papio</i>).</p

Photograph of the anterior aspect of forearm right of <i>C.l.</i>

<p>The arrow is indicating the pronator quadratus muscle. (bar = 0,5 cm).</p

Comparative analyses of the flexor superficial muscles forearm among <i>Cebus libidinosus</i> (<i>C.l.</i>), human (<i>Homo</i>), chimpanzee (<i>Pan</i>) and baboon (<i>Papio</i>).

<p>Comparative analyses of the flexor superficial muscles forearm among <i>Cebus libidinosus</i> (<i>C.l.</i>), human (<i>Homo</i>), chimpanzee (<i>Pan</i>) and baboon (<i>Papio</i>).</p

Photograph of the anterior aspect of forearm right of a <i>Cebus libidinosus (C.l.)</i>.

<p>1).brachioradialis muscle, 2) flexor carpi radialis muscle, 3) flexor digitorum superficialis muscle, 4) palmaris longus muscle, 5) flexor carpi ulnaris muscle and, 6) pronator teres muscle. (bar = 1,2 cm).</p