Functional and phylogenetic variation in anthropoid incisor size.

Area of Science:

• Primate paleontology
• Comparative anatomy
• Functional morphology

Background:

• Previous research indicated frugivorous anthropoids have wider incisors than folivores relative to body mass.
• Studies also suggested catarrhines possess relatively wider incisors than platyrrhines.

Purpose of the Study:

• To reexamine the relationship between anthropoid incisor width, diet, and phylogeny.
• To utilize mandibular length as a biomechanical standard for quantifying relative incisor width.

Main Methods:

• Collected dental, mandibular, and body-mass data for 86 anthropoid species from existing literature.
• Size-adjusted incisor width using shape ratios, with mandibular length and body mass as denominators.
• Analyzed dietary and phylogenetic effects using phylogenetic generalized least squares.

Main Results:

• Mandible-based ratios showed similar patterns to body mass-based ratios, confirming frugivores have relatively wider incisors than folivores.
• Limited support was found for a stronger dietary effect in platyrrhines using mandible-based ratios.
• Neither ratio indicated an overall difference in incisor width between platyrrhines and catarrhines.

Conclusions:

• While both ratio methods support a link between incisor size and diet, mandible-based ratios may be more sensitive to dietary variation at smaller phylogenetic scales.
• The findings challenge the notion that platyrrhines generally have narrower incisors than catarrhines.
• Greater incisor functional diversity within platyrrhines may explain previously observed differences between the clades.