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This study uses camera\u2010trap footage to provide the first assessment of wild orangutan terrestrial locomotor and postural behavior on natural substrates.\n                    <\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Materials and Methods<\/jats:title>\n                    <jats:p>Video footage of orangutans from motion\u2010activated cameras in the Gunung Palung National Park, West Kalimantan, Indonesia was collected over a five\u2010year period. The resulting 100 instances of orangutan terrestriality were analyzed to document incidences of positional behavior, including hand and foot postures as well as overstride pattern during locomotion and qualitative assessment of hindlimb joint excursions during orthograde behaviors.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Results<\/jats:title>\n                    <jats:p>\n                      When locomoting terrestrially,\n                      <jats:styled-content style=\"fixed-case\">\n                        <jats:italic>Pongo pygmaeus<\/jats:italic>\n                      <\/jats:styled-content>\n                      primarily engaged in quadrupedal fist\u2010walking with heel\u2010strike. Wrist position and overstride pattern during quadrupedal walking were variable both within and between individuals. For posture, individuals were captured standing upright more often than pronograde, both monopedally and bipedally, and almost always with full extension of the hip and knee.\n                    <\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Discussion<\/jats:title>\n                    <jats:p>These observations of wild orangutan terrestrial positional behavior address prior ambiguities related to hand and foot positioning during locomotion. Maintained full extension of the hindlimb in the absence of substrate compliance indicates the form of bipedalism orangutans use in the trees translates to natural terrestrial substrates. Finally, the high proportion of observations with asymmetrical movement and posture may indicate a lateral decoupling of limbs in addition to the expected fore\u2010 and hindlimb independence of apes, suggesting orangutan positional adaptability is intrinsic regardless of substrate.<\/jats:p>\n                  <\/jats:sec>","DOI":"10.1002\/ajpa.70245","type":"journal-article","created":{"date-parts":[[2026,4,6]],"date-time":"2026-04-06T09:39:57Z","timestamp":1775468397000},"update-policy":"https:\/\/doi.org\/10.1002\/crossmark_policy","source":"Crossref","is-referenced-by-count":1,"title":["Terrestrial Positional Behavior of Wild\n                    <i>Pongo pygmaeus<\/i>"],"prefix":"10.1002","volume":"189","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-4078-196X","authenticated-orcid":false,"given":"Emily R.","family":"Orlikoff","sequence":"first","affiliation":[{"name":"Department of Anthropology University of Michigan  Ann Arbor Michigan USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Gene R.","family":"Estrada","sequence":"additional","affiliation":[{"name":"Department of Anthropology University of Michigan  Ann Arbor Michigan USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Andrew J.","family":"Marshall","sequence":"additional","affiliation":[{"name":"Department of Anthropology University of Michigan  Ann Arbor Michigan USA"},{"name":"Department of Ecology and Evolutionary Biology University of Michigan  Ann Arbor Michigan USA"},{"name":"School of Environment and Sustainability University of Michigan  Ann Arbor Michigan USA"},{"name":"Program in the Environment University of Michigan  Ann Arbor Michigan USA"},{"name":"Program in Computing for the Arts and Sciences University of Michigan  Ann Arbor Michigan USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Heiko U.","family":"Wittmer","sequence":"additional","affiliation":[{"name":"School of Biological Sciences Victoria University of Wellington  Wellington New Zealand"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Endro","family":"Setiawan","sequence":"additional","affiliation":[{"name":"Gunung Palung National Park Bureau  Ketapang West Kalimantan Indonesia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Cheryl D.","family":"Knott","sequence":"additional","affiliation":[{"name":"Department of Anthropology Boston University  Boston Massachusetts USA"},{"name":"Department of Biology Boston University  Boston Massachusetts USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-8819-5118","authenticated-orcid":false,"given":"Lauren","family":"Sarringhaus","sequence":"additional","affiliation":[{"name":"Department of Anthropology University of Michigan  Ann Arbor Michigan USA"},{"name":"Department of Biology James Madison University  Harrisonburg Virginia USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-9399-2157","authenticated-orcid":false,"given":"Laura M.","family":"MacLatchy","sequence":"additional","affiliation":[{"name":"Department of Anthropology University of Michigan  Ann Arbor Michigan USA"},{"name":"University of Michigan Museum of Paleontology  Ann Arbor Michigan USA"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"311","published-online":{"date-parts":[[2026,4,6]]},"reference":[{"key":"e_1_2_10_2_1","doi-asserted-by":"publisher","DOI":"10.1038\/srep04024"},{"key":"e_1_2_10_3_1","doi-asserted-by":"publisher","DOI":"10.1002\/ajp.22460"},{"key":"e_1_2_10_4_1","doi-asserted-by":"publisher","DOI":"10.1002\/ajp.1350120104"},{"key":"e_1_2_10_5_1","doi-asserted-by":"publisher","DOI":"10.1002\/ajpa.1330470206"},{"key":"e_1_2_10_6_1","doi-asserted-by":"publisher","DOI":"10.3390\/ani11071856"},{"key":"e_1_2_10_7_1","doi-asserted-by":"publisher","DOI":"10.1098\/rstb.2010.0035"},{"key":"e_1_2_10_8_1","first-page":"135","article-title":"The Biomechanical Evolution of Erect Bipedality","volume":"243","author":"Crompton R. 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