Meeting Abstract
Wild primates navigate arboreal habitats that include multiple, inconsistent substrates with diverse characteristics. However, our understanding of primate quadrupedal gait kinematics is limited to mostly laboratory data on single substrate use. We present a comparative analysis of wild platyrrhine quadrupedal gait kinematics on discontinuous, natural substrates to further investigate the adaptive context in which unique aspects of primate quadrupedalism evolved. We collected high-speed video of platyrrhines in Amazonian Ecuador and quantified kinematic adjustments to substrate discontinuities. We coded footfall events and substrate characteristics for locomotor bouts containing multiple strides and multiple substrates (n=56) and examined the effect of substrate discontinuities on kinematics. Saimiri sciureus adjusted timing between touchdowns of forelimb pairs and between ipsilateral fore-hind pairs in response to substrate discontinuities, but Lagothrix lagothricha did not adjust interlimb timing. Saimiri used more asymmetrical walking gaits when moving across discontinuous substrates whereas Lagothrix used significantly more diagonal sequence symmetrical walking gaits. Our results demonstrate that quadrupedal walking is more diverse and flexible than previously documented in laboratory studies, and that taxa adjust kinematics differently – perhaps reflecting unique morphological adaptations to arborealism (e.g., prehensile tails). Primate gait evolution may have favored kinematic flexibility, permitting animals to respond to discontinuities and substrate changes in their environment. Funding: NSF Grants BCS-1640552, BCS-1640453
