The effects of natural substrate discontinuities on the quadrupedal gait kinematics of free‐ranging Saimiri sciureus.
positional behavior; arboreal locomotion; KINEMATICS; PRIMATES; ECUADOR; QUADRUPEDALISM; squirrel monkeys; asymmetrical walking; squirrel monkeys; wild primates; COMPLEX matrices; HUMAN kinematics; WALKING speed
Wild primates encounter complex matrices of substrates that differ in size, orientation, height, and compliance, and often move on multiple, discontinuous substrates within a single bout of locomotion. Our current understanding of primate gait is limited by artificial laboratory settings in which primate quadrupedal gait has primarily been studied. This study analyzes wild Saimiri sciureus (common squirrel monkey) gait on discontinuous substrates to capture the realistic effects of the complex arboreal habitat on walking kinematics. We collected high‐speed video footage at Tiputini Biodiversity Station, Ecuador between August and October 2017. Overall, the squirrel monkeys used more asymmetrical walking gaits than symmetrical gaits, and specifically asymmetrical lateral sequence walking gaits when moving across discontinuous substrates. When individuals used symmetrical gaits, they used diagonal sequence gaits more than lateral sequence gaits. In addition, individuals were more likely to change their footfall sequence during strides on discontinuous substrates. Squirrel monkeys increased the time lag between touchdowns both of ipsilaterally paired limbs (pair lag) and of the paired forelimbs (forelimb lag) when walking across discontinuous substrates compared to continuous substrates. Results indicate that gait flexibility and the ability to alter footfall patterns during quadrupedal walking may be critical for primates to safely move in their complex arboreal habitats. Notably, wild squirrel monkey quadrupedalism is diverse and flexible with high proportions of asymmetrical walking. Studying kinematics in the wild is critical for understanding the complexity of primate quadrupedalism. Research Highlights: Free‐ranging Saimiri sciureus quadrupedal gait is more variable than has previously been shown in the laboratory setting and includes a combination of asymmetrical and symmetrical walking gaits, lateral sequence gaits, and diagonal sequence gaits when moving across discontinuous substrates.Primates utilize gait flexibility to navigate their complex, arboreal habitats.Saimiri increases the delay in forelimb touchdowns when moving across discontinuous substrates, supporting the hypothesis that forelimbs may be used to explore the stability of a new substrate. [ABSTRACT FROM AUTHOR]
McNamara Allison; Dunham Noah T; Shapiro Liza J; Young Jesse W
American Journal Of Primatology
2019
2019-09
Journal Article
<a href="http://doi.org/10.1002/ajp.23055" target="_blank" rel="noreferrer noopener">10.1002/ajp.23055</a><br /><br /><span>PMID: 31578748</span>
Effects of substrate and phylogeny on quadrupedal gait in free‐ranging platyrrhines.
arboreal quadrupedalism; MAMMALS; locomotion; platyrrhine; PHYLOGENY; QUADRUPEDALISM; NEW World monkeys; phylogenetic eigenvector; COSTA Rica
Objectives: Primate diagonal sequence (DS) gaits are often argued to be an adaptation for moving and foraging in the fine‐branch niche; however, existing data have come predominantly from laboratory studies that are limited in taxonomic breadth and fail to account for the structural and ecological variation of natural substrates. We test the extent to which substrate diameter and orientation influence gait sequence type and limb phase in free‐ranging primates, as well as how phylogenetic relatedness might condition response patterns. Materials and methods: We filmed quadrupedal locomotion in 11 platyrrhine species at field sites in Ecuador and Costa Rica and measured the diameter and orientation of locomotor substrates using remote sensors. We quantified limb phase values and classified strides by gait sequence type (N = 988 strides). Results: Our results show that most of the species in our sample consistently used DS gaits, regardless of substrate diameter or orientation; however, all taxa also used asymmetrical and/or lateral sequence gaits. By incorporating phylogenetic eigenvectors into our models, we found significant differences in gait sequence patterns and limb phase values among the major platyrrhine clades, suggesting that phylogeny may be a better predictor of gait than substrate diameter or orientation. Discussion: Our field data generally corroborate locomotor patterns from laboratory studies but capture additional aspects of gait variability and flexibility in response to the complexity of natural environments. Overall, our results suggest that DS gaits are not exclusively tailored to narrow or oblique substrates but are used on arboreal substrates in general. [ABSTRACT FROM AUTHOR]
Dunham Noah T; McNamara Allison; Shapiro Liza J; Hieronymus Tobin L; Phelps Taylor; Young Jesse W
American Journal Of Physical Anthropology
2019
2019-12
Journal Article
<a href="http://doi.org/10.1002/ajpa.23942" target="_blank" rel="noreferrer noopener">10.1002/ajpa.23942</a>
Kinematics of quadrupedal locomotion in sugar gliders (Petaurus breviceps): effects of age and substrate size
arboreal locomotion; Arboreality; baboons papio-cynocephalus; cebus-apella; diagonal-sequence walking; Gait; Kinematics; Life Sciences & Biomedicine - Other Topics; life-history; limb mass-distribution; Marsupials; monkeys; monkeys saimiri-boliviensis; ontogeny; postnatal-development; Quadrupedalism; symmetrical gaits; vervet
Arboreal mammals face unique challenges to locomotor stability. This is particularly true with respect to juveniles, who must navigate substrates similar to those traversed by adults, despite a reduced body size and neuromuscular immaturity. Kinematic differences exhibited by juveniles and adults on a given arboreal substrate could therefore be due to differences in body size relative to substrate size, to differences in neuromuscular development, or to both. We tested the effects of relative body size and age on quadrupedal kinematics in a small arboreal marsupial (the sugar glider, Petaurus breviceps; body mass range of our sample 33-97 g). Juvenile and adult P. breviceps were filmed moving across a flat board and three poles 2.5, 1.0 and 0.5 cm in diameter. Sugar gliders (regardless of age or relative speed) responded to relative decreases in substrate diameter with kinematic adjustments that promote stability; they increased duty factor, increased the average number of supporting limbs during a stride, increased relative stride length and decreased relative stride frequency. Limb phase increased when moving from the flat board to the poles, but not among poles. Compared with adults, juveniles (regardless of relative body size or speed) used lower limb phases, more pronounced limb flexion, and enhanced stability with higher duty factors and a higher average number of supporting limbs during a stride. We conclude that although substrate variation in an arboreal environment presents similar challenges to all individuals, regardless of age or absolute body size, neuromuscular immaturity confers unique problems to growing animals, requiring kinematic compensation.
Shapiro L J; Young J W
Journal of Experimental Biology
2012
2012-02
Journal Article
<a href="http://doi.org/10.1242/jeb.062588" target="_blank" rel="noreferrer noopener">10.1242/jeb.062588</a>
Is primate-like quadrupedalism necessary for fine-branch locomotion? A test using sugar gliders (Petaurus breviceps)
Anthropology; arboreal locomotion; Arboreality; banksia-spinulosa; bonobos pan-paniscus; cheirogaleus-medius; compliant; diagonal-sequence walking; Evolutionary Biology; Gait; Kinematics; Marsupials; monkeys saimiri-boliviensis; opossum monodelphis-domestica; papio-cynocephalus; primates; Quadrupedalism; symmetrical gaits; walking
Locomotor features shared by arboreal marsupials and primates are frequently cited as a functional complex that evolved in the context of a "fine branch niche." Adaptation to a fine branch niche cannot be understood without considering that small and large arboreal mammals may differ in their biomechanical response to a given branch size. We tested the effects of substrate diameter and orientation on quadrupedal kinematics in a small arboreal marsupial (the sugar glider, Petaurus breviceps). P. breviceps individuals were filmed moving across a flat horizontal surface and on horizontal, inclining and declining poles of diameter 2.5, 1.0, and 0.5 cm. Gait frequencies, limb phases, speeds and duty factors were compared across substrate conditions. P breviceps had a clear preference for lateral sequence/diagonal couplets gaits, regardless of substrate type, diameter or orientation. Limb phase was significantly influenced by substrate type (higher limb phases on poles vs. the flat surface) and by orientation (higher limb phases on inclined vs. horizontal poles), but was not influenced by pole diameter. Speed was lowest on declines, and duty factors (at a given speed) were highest on the flat board, smallest pole, and on declines. P. breviceps exhibited some parallels, but also some departures from the characteristic patterns of other arboreal marsupials and primates. Notably, limb phase values, on average, remained lower in P. breviceps than those recorded for primates or other arboreal marsupials. We suggest that arboreal mammals of different body sizes may use dissimilar, but apparently equally successful strategies for navigating a "fine branch niche." (C) 2010 Elsevier Ltd. All rights reserved.
Shapiro L J; Young J W
Journal of Human Evolution
2010
2010-04
Journal Article
<a href="http://doi.org/10.1016/j.jhevol.2009.12.002" target="_blank" rel="noreferrer noopener">10.1016/j.jhevol.2009.12.002</a>
Body size and the small branch niche: using marsupial ontogeny to model primate locomotor evolution.
Animals; Arboreality; Biological Evolution; Biomechanical Phenomena; Body Size/*physiology; Female; Foot/anatomy & histology/physiology; Kinematics; Locomotion/*physiology; Male; Marsupialia/*anatomy & histology/*physiology; Monodelphis; Petaurus; Quadrupedalism
Recently proposed ancestral locomotor and morphological 'stages' leading to the evolution of primates have emphasized small body size, and a transition from a clawed non-grasping stage, to a clawed, grasping stage with clawless opposable hallux, to a fully-nailed primate with grasping extremities. This evolutionary transition was presumably associated with frequent use of the small branch niche. To model elements of these evolutionary transitions, we investigate how body size, substrate size, substrate orientation and grasping morphology interact to influence quadrupedal kinematics within and between ontogenetic samples of two small-bodied marsupials, one arboreal (Petaurus breviceps) and the other mainly terrestrial (Monodelphis domestica). Longitudinal morphometric and kinematic data were collected from four juvenile P. breviceps (33-75 g) and two juvenile M. domestica (18-95 g) walking across poles of three diameters (2.5, 1.0, and 0.5 cm) and three orientations (horizontal, 30 degrees incline, 30 degrees decline). The two species responded similarly to some substrate conditions, but diverged in response to others. Kinematic divergence between the two species reflects Monodelphis' relatively shorter digits, reduced grasping ability and greater need for stabilizing mechanisms on narrow substrates. At a given relative body size or pole orientation, Monodelphis used higher limb duty factors, more limbs in support per stride, lower limb phases, and in some conditions, faster speeds compared with Petaurus. Interspecific differences were the least distinct on declined poles, highlighting the particular challenge of this substrate condition, even for arboreally adapted species. Small-bodied, arboreal primate ancestors would likely have employed the kinematic mechanisms common to our model taxa, but those with enhanced grasping adaptations would most likely not have required the increased level of stabilizing mechanisms exhibited by Monodelphis. Thus, using these two species as locomotor models has underscored the functional importance of grasping extremities in primate origins, even if ancestral primates were very small in body size.
Shapiro Liza J; Young Jesse W; VandeBerg John L
Journal of human evolution
2014
2014-03
Article information provided for research and reference use only. All rights are retained by the journal listed under publisher and/or the creator(s).
<a href="http://doi.org/10.1016/j.jhevol.2013.12.006" target="_blank" rel="noreferrer noopener">10.1016/j.jhevol.2013.12.006</a>
Getting into Shape: Limb Bone Strength in Perinatal Lemur catta and Propithecus coquereli.
cross-sectional geometry; material properties; ontogeny; quadrupedalism; vertical clinging and leaping
Functional studies of skeletal anatomy are predicated on the fundamental assumption that form will follow function. For instance, previous studies have shown that the femora of specialized leaping primates are more robust than those of more generalized primate quadrupeds. Are such differences solely a plastic response to differential loading patterns during postnatal life, or might they also reflect more canalized developmental mechanisms present at birth? Here, we show that perinatal Lemur catta, an arboreal/terrestrial quadruped, have less robust femora than perinatal Propithecus coquereli, a closely related species specialized for vertical clinging and leaping (a highly unusual locomotor mode in which the hindlimbs are used to launch the animal between vertical tree trunks). These results suggest that functional differences in long bone cross-sectional dimensions are manifest at birth, belying simple interpretations of adult postcranial form as a direct record of loading patterns during postnatal life. Despite these significant differences in bone robusticity, we find that hindlimb bone mineralization, material properties, and measures of whole-bone strength generally overlap in perinatal L. catta and P. coquereli, indicating little differentiation in postcranial maturity at birth despite known differences in the pace of craniodental development between the species. In a broader perspective, our results likely reflect evolution acting during prenatal ontogeny. Even though primates are notable for relatively prolonged gestation and postnatal parental care, neonates are not buffered from selection, perhaps especially in the unpredictable and volatile environment of Madagascar. Anat Rec, 2018. (c) 2018 Wiley Periodicals, Inc.
Young Jesse W; Jankord Kathryn; Saunders Marnie M; Smith Timothy D
Anatomical record (Hoboken, N.J. : 2007)
2018
2018-12
Article information provided for research and reference use only. All rights are retained by the journal listed under publisher and/or the creator(s).
<a href="http://doi.org/10.1002/ar.24045" target="_blank" rel="noreferrer noopener">10.1002/ar.24045</a>
A user's guide for the quantitative analysis of substrate characteristics and locomotor kinematics in free-ranging primates.
branch diameter; compliance; gait; orientation; quadrupedalism
OBJECTIVES: Laboratory studies have yielded important insights into primate locomotor mechanics. Nevertheless, laboratory studies fail to capture the range of ecological and structural variation encountered by free-ranging primates. We present techniques for collecting kinematic data on wild primates using consumer grade high-speed cameras and demonstrate novel methods for quantifying metric variation in arboreal substrates. MATERIALS AND METHODS: These methods were developed and applied to our research examining platyrrhine substrate use and locomotion at the Tiputini Biodiversity Station, Ecuador. Modified GoPro cameras equipped with varifocal zoom lenses provided high-resolution footage (1080 p.; 120 fps) suitable for digitizing gait events. We tested two methods for remotely measuring branch diameter: the parallel laser method and the distance meter photogrammetric method. A forestry-grade laser rangefinder was used to quantify substrate angle and a force gauge was used to measure substrate compliance. We also introduce GaitKeeper, a graphical user interface for MATLAB, designed for coding quadrupedal gait. RESULTS: Parallel laser and distance meter methods provided accurate estimations of substrate diameter (percent error: 3.1-4.5%). The laser rangefinder yielded accurate estimations of substrate orientation (mean error = 2.5 degrees ). Compliance values varied tremendously among substrates but were largely explained by substrate diameter, substrate length, and distance of measurement point from trunk. On average, larger primates used relatively small substrates and traveled higher in the canopy. DISCUSSION: Ultimately, these methods will help researchers identify more precisely how primate gait kinematics respond to the complexity of arboreal habitats, furthering our understanding of the adaptive context in which primate quadrupedalism evolved.
Dunham Noah T; McNamara Allison; Shapiro Liza; Hieronymus Tobin; Young Jesse W
American journal of physical anthropology
2018
2018-11
Article information provided for research and reference use only. All rights are retained by the journal listed under publisher and/or the creator(s).
<a href="http://doi.org/10.1002/ajpa.23686" target="_blank" rel="noreferrer noopener">10.1002/ajpa.23686</a>