naa a22 4500 510744834 CHVBK 20180411083042.0 cr unu---uuuuu 180411e20130101xx s 000 0 eng 10.1007/s13364-012-0099-4 doi (NATIONALLICENCE)springer-10.1007/s13364-012-0099-4 A mechanical link model of two-toed sloths: no pendular mechanics during suspensory locomotion [Elektronische Daten] [John Nyakatura, Emanuel Andrada] Sloths are morphologically specialized in suspensory quadrupedal locomotion and posture. During steady-state locomotion they utilize a trot-like footfall sequence. Contrasting the growing amount of published accounts of the functional morphology and kinematics of sloth locomotion, no study concerned with the dynamics of their quadrupedal suspensory locomotion has been conducted. Brachiating primates have been shown to travel at low mechanical costs using pendular mechanics, but this is associated with considerable dynamic forces exerted onto the support. To test whether sloth locomotion can be described by simple connected pendulum mechanics, we analyzed the dynamics of sloth locomotion with use of a mechanical segment link model. The model integrates the body segment parameters and is driven by kinematic data with both segment parameters and kinematic data obtained from the same sloth individual. No simple pendular mechanics were present. We then used the model to carry out an inverse dynamic analysis. The analysis allowed us to estimate net limb joint torques and substrate reaction forces during the contact phases. Predominant flexing limb joint torque profiles in the shoulder, elbow, hip, and knee are in stark contrast to published dominant extensor torques in the limb joints of pronograde quadrupedal mammals. This dissimilarity likely reflects the inverse orientation of the sloth towards the gravity vector. Nevertheless, scapular pivot and shoulder seem to provide the strongest torque for progression as expected based on unchanged basic kinematic pattern previously described. Our model predicts that sloths actively reduce the dynamical forces and moments that are transmitted onto the support. We conclude that these findings reflect the need to reduce the risk of breaking supports because in this case sloths would likely be unable to react quickly enough to prevent potentially lethal falls. To achieve this, sloths seem to avoid the dynamical consequences of effective pendular mechanics. Mammal Research Institute, Polish Academy of Sciences, Białowieża, Poland, 2012 Pendulum nationallicence Joint torques nationallicence Substrate reaction forces nationallicence Inverse dynamics analysis nationallicence Nyakatura John Institut für Spezielle Zoologie und Evolutionsbiologie mit Phyletischem Museum, Friedrich-Schiller-Universität, 07743, Jena, Germany aut Andrada Emanuel Fachgebiet Biomechatronik, Technische Universität Ilmenau, 98684, Ilmenau, Germany aut Acta Theriologica Springer-Verlag 58/1(2013-01-01), 83-93 0001-7051 58:1<83 2013 58 13364 https://doi.org/10.1007/s13364-012-0099-4 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/s13364-012-0099-4 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Nyakatura John Institut für Spezielle Zoologie und Evolutionsbiologie mit Phyletischem Museum, Friedrich-Schiller-Universität, 07743, Jena, Germany aut NATIONALLICENCE 700 1- Andrada Emanuel Fachgebiet Biomechatronik, Technische Universität Ilmenau, 98684, Ilmenau, Germany aut NATIONALLICENCE 773 0- Acta Theriologica Springer-Verlag 58/1(2013-01-01), 83-93 0001-7051 58:1<83 2013 58 13364 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer