Acta Anthropologica Sinica ›› 2020, Vol. 39 ›› Issue (04): 532-554.doi: 10.16359/j.cnki.cn11-1963/q.2020.0061

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Inferring the locomotor behavior of fossil hominoids from phalangeal curvature using a novel method: Lufengpithecus as a case study

ZHANG Yingqi1,2,3(), Terry HARRISON4, JI Xueping5,6   

  1. 1. Key Laboratory of Vertebrate Evolution and Human Origins, Institute of Vertebrate Paleontology and Paleoanthropology (IVPP), Chinese Academy of Sciences, Beijing 100044
    2. CAS Center for Excellence in Life and Paleoenvironment, Beijing 100044
    3. State Key Laboratory of Palaeobiology and Stratigraphy, Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, Nanjing 210008
    4. Center for the Study of Human Origins, Department of Anthropology, New York University, New York 10003
    5. Department of Paleoanthropology, Yunnan Institute of Cultural Relics and Archaeology, Kunming 650118
    6. School of Geoscience, Yunnan University, Kunming 650500
  • Received:2020-06-03 Revised:2020-09-10 Online:2020-11-15 Published:2020-11-23

Abstract:

Phalangeal curvature has long been used to infer locomotor behavior in fossil primates. Several methods, such as radius of curvature, included angle (IA), normalized curvature moment arm (NCMA), and high-resolution polynomial curve fitting (HR-PCF), have been employed to quantify and compare phalangeal curvature. However, each method has theoretical or technical limitations in the degree to which they are able to accurately quantify phalangeal curvature, and these undermine the applicability and utility of these methods. A novel method of analyzing phalangeal curvature, based on 4th order polynomial curve fitting on geometric morphometric landmark data (GM-PCF), is described here as an alternative method. GM-PCF avoids the problems with previously employed methods and provides a more accurate representation of phalangeal curvature. It uses normalized phalangeal curve height (NPCH) as a quantitative indicator of phalangeal curvature, and depicts the average normalized phalangeal curve for qualitative comparison of curvature. Furthermore, it provides additional information about phalangeal proportions that are crucial for interpreting the functional relationships of phalangeal curvature. GM-PCF is also capable of dealing with incomplete phalanges. To test the utility of the new method, fifteen groups of extant anthropoid primates are used as a reference sample for comparison with two species of Miocene hominoids from China, Lufengpithecus lufengensis and Lufengpithecus hudienensis. The results of the GM-PCF analysis are used to infer the most likely locomotor behavior of the fossil hominoids.

Key words: Phalangeal curvature, Polynomial curve fitting, Locomotion, Hominoids, Lufengpithecus

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