A new method to quantify mandibular corpus shape in extant great apes and its potential application to the hominoid fossil record

Mary E Pitirri, David Begun

Research output: Contribution to journalArticle

Abstract

Objectives: Mandibular corpus robusticity (corpus breadth/corpus height) is the most commonly utilized descriptor of the mandibular corpus in the great ape and hominin fossil records. As a consequence of its contoured shape, linear metrics used to characterize mandibular robusticity are inadequate to quantify the shape of the mandibular corpus. Here, we present an alternative to the traditional assessment of mandibular shape by analyzing the outline of the mandibular corpus in cross-section using landmarks and semilandmarks. Materials and methods: Outlines of the mandibular corpus in cross-section between M1 and M2 were quantified in a sample of hominoids and analyzed using generalized Procrustes analysis, Procrustes ANOVA, CVA, and cluster analysis. Corpus breadth and width were also collected from the same sample and analyzed using regression, ANOVA, and cluster analysis. Results: Analysis of corpus outline shape revealed significant differences in mandibular corpus shape that are independent of size and sex at the genus level across hominoids. Cluster analysis based on the analysis of corpus outline shape results in almost all specimens grouping based on taxonomic affinity (99.28% correct classification). Comparison of these results to results using traditional measures of mandibular robusticity shows that analysis of the outline of the corpus in cross-section discriminate extant great apes more reliably. Conclusion: The strong taxonomic signal revealed by this analysis indicates that quantification of the outline of the mandibular corpus more fully captures mandibular corpus shape and offers the potential for greater power in discriminating among taxa in the hominoid fossil record.

Original languageEnglish (US)
Pages (from-to)318-328
Number of pages11
JournalAmerican Journal of Physical Anthropology
Volume168
Issue number2
DOIs
StatePublished - Feb 1 2019

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Fossils
Hominidae
Cluster Analysis
cluster analysis
Analysis of Variance
Regression Analysis
great power
quantification
grouping
regression analysis

All Science Journal Classification (ASJC) codes

  • Anatomy
  • Anthropology

Cite this

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title = "A new method to quantify mandibular corpus shape in extant great apes and its potential application to the hominoid fossil record",
abstract = "Objectives: Mandibular corpus robusticity (corpus breadth/corpus height) is the most commonly utilized descriptor of the mandibular corpus in the great ape and hominin fossil records. As a consequence of its contoured shape, linear metrics used to characterize mandibular robusticity are inadequate to quantify the shape of the mandibular corpus. Here, we present an alternative to the traditional assessment of mandibular shape by analyzing the outline of the mandibular corpus in cross-section using landmarks and semilandmarks. Materials and methods: Outlines of the mandibular corpus in cross-section between M1 and M2 were quantified in a sample of hominoids and analyzed using generalized Procrustes analysis, Procrustes ANOVA, CVA, and cluster analysis. Corpus breadth and width were also collected from the same sample and analyzed using regression, ANOVA, and cluster analysis. Results: Analysis of corpus outline shape revealed significant differences in mandibular corpus shape that are independent of size and sex at the genus level across hominoids. Cluster analysis based on the analysis of corpus outline shape results in almost all specimens grouping based on taxonomic affinity (99.28{\%} correct classification). Comparison of these results to results using traditional measures of mandibular robusticity shows that analysis of the outline of the corpus in cross-section discriminate extant great apes more reliably. Conclusion: The strong taxonomic signal revealed by this analysis indicates that quantification of the outline of the mandibular corpus more fully captures mandibular corpus shape and offers the potential for greater power in discriminating among taxa in the hominoid fossil record.",
author = "Pitirri, {Mary E} and David Begun",
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