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Quantification of the position and depth of the flexor hallucis longus groove in euarchontans, with implications for the evolution of primate positional behavior.

Publication ,  Journal Article
Yapuncich, GS; Seiffert, ER; Boyer, DM
Published in: Am J Phys Anthropol
June 2017

OBJECTIVE: On the talus, the position and depth of the groove for the flexor hallucis longus tendon have been used to infer phylogenetic affinities and positional behaviors of fossil primates. This study quantifies aspects of the flexor hallucis longus groove (FHLG) to test if: (1) a lateral FHLG is a derived strepsirrhine feature, (2) a lateral FHLG reflects inverted and abducted foot postures, and (3) a deeper FHLG indicates a larger muscle. METHODS: We used linear measurements of microCT-generated models from a sample of euarchontans (n = 378 specimens, 125 species) to quantify FHLG position and depth. Data are analyzed with ANOVA, Ordinary and Phylogenetic Generalized Least Squares, and Bayesian Ancestral State Reconstruction (ASR). RESULTS: Extant strepsirrhines, adapiforms, plesiadapiforms, dermopterans, and Ptilocercus exhibit lateral FHLGs. Extant anthropoids, subfossil lemurs, and Tupaia have medial FHLGs. FHLGs of omomyiforms and basal fossil anthropoids are intermediate between those of strepsirrhines and extant anthropoids. FHLG position has few correlations with pedal inversion features. Relative FHLG depth is not significantly correlated with body mass. ASRs support a directional model for FHLG position and a random walk model for FHLG depth. CONCLUSIONS: The prevalence of lateral FHLGs in many non-euprimates suggests a lateral FHLG is not a derived strepsirrhine feature. The lack of correlations with pedal inversion features suggests a lateral FHLG is not a sufficient indicator of strepsirrhine-like foot postures. Instead, a lateral FHLG may reduce the risk of tendon displacement in abducted foot postures on large diameter supports. A deep FHLG does not indicate a larger muscle, but likely reduces bowstringing during plantarflexion.

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Published In

Am J Phys Anthropol

DOI

EISSN

1096-8644

Publication Date

June 2017

Volume

163

Issue

2

Start / End Page

367 / 406

Location

United States

Related Subject Headings

  • Talus
  • Primates
  • Phylogeny
  • Male
  • Humans
  • History, Ancient
  • Fossils
  • Fibula
  • Female
  • Biological Evolution
 

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Yapuncich, G. S., Seiffert, E. R., & Boyer, D. M. (2017). Quantification of the position and depth of the flexor hallucis longus groove in euarchontans, with implications for the evolution of primate positional behavior. Am J Phys Anthropol, 163(2), 367–406. https://doi.org/10.1002/ajpa.23213
Yapuncich, Gabriel S., Erik R. Seiffert, and Doug M. Boyer. “Quantification of the position and depth of the flexor hallucis longus groove in euarchontans, with implications for the evolution of primate positional behavior.Am J Phys Anthropol 163, no. 2 (June 2017): 367–406. https://doi.org/10.1002/ajpa.23213.
Yapuncich, Gabriel S., et al. “Quantification of the position and depth of the flexor hallucis longus groove in euarchontans, with implications for the evolution of primate positional behavior.Am J Phys Anthropol, vol. 163, no. 2, June 2017, pp. 367–406. Pubmed, doi:10.1002/ajpa.23213.
Journal cover image

Published In

Am J Phys Anthropol

DOI

EISSN

1096-8644

Publication Date

June 2017

Volume

163

Issue

2

Start / End Page

367 / 406

Location

United States

Related Subject Headings

  • Talus
  • Primates
  • Phylogeny
  • Male
  • Humans
  • History, Ancient
  • Fossils
  • Fibula
  • Female
  • Biological Evolution