On Saturday, October 15, 2022 at 5:50:24 AM UTC-4, DD'eDeN aka note/nickname/alas_my_loves wrote:
https://www.sciencedirect.com/science/article/abs/pii/S0047248415001839 Spine vertebrae
Journal of Human Evolution
Volume 88, November 2015, Pages 160-179
Giant pandas (Carnivora: Ailuropoda melanoleuca) and living hominoids converge on lumbar vertebral adaptations to orthograde trunk posture
Author links open overlay panel Gabrielle A.RussoaScott A.Williamsbcd
https://doi.org/10.1016/j.jhevol.2015.06.015
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Abstract
Living hominoids share a common body plan characterized by a gradient of derived postcranial features that distinguish them from their closest living relatives, cercopithecoid monkeys. However, the evolutionary scenario(s) that led to the derived
postcranial features of hominoids are uncertain. Explanations are complicated by the fact that living hominoids vary considerably in positional behaviors, and some Miocene hominoids are morphologically, and therefore probably behaviorally, distinct from
modern hominoids. Comparative studies that aim to identify morphologies associated with specific components of positional behavioral repertoires are an important avenue of research that can improve our understanding of the evolution and adaptive
significance of the hominoid postcranium. Here, we employ a comparative approach to offer additional insight into the evolution of the hominoid lumbar vertebral column. Specifically, we tested whether giant pandas (Carnivora: Ailuropoda melanoleuca)
converge with living hominoids on lumbar vertebral adaptations to the single component of their respective positional behavioral repertoires that they share—orthograde (i.e., upright) trunk posture. We compare lumbar vertebral morphologies of
Ailuropoda to those of other living ursids and caniform outgroups (northern raccoons and gray wolves). Mirroring known differences between living hominoids and cercopithecoids, Ailuropoda generally exhibits fewer, craniocaudally shorter lumbar vertebrae
with more dorsally positioned transverse processes that are more dorsally oriented and laterally directed, and taller, more caudally directed spinous processes than other caniforms in the sample. Our comparative evidence lends support to a potential
evolutionary scenario in which the acquisition of hominoid-like lumbar vertebral morphologies may have evolved for generalized orthograde behaviors and could have been exapted for suspensory behavior in crown hominoids and for other locomotor
specializations (e.g., brachiation) in extant lineages.
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GM claims dolphins and sloths share this trait, indicating that bipedalism is not proven. However orthograde posture is likely, ancestral sloths & pandas stood & leaned on trees bipedally while foraging. Dolphin breathing and loss of rear limbs may have
influenced their spinal vertebrae before becoming super-streamlined and evolving instant surface respiration. Hominoids became orthograde bipeds on horizontal tree branches from bimanual brachiation (plucking with feet) and bipedal walking (plucking with
hands), unlike non-brachiating quadrupedal monkeys.
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