Molar shape variability in platyrrhine primates

Area of Science:

• Primate evolutionary biology
• Comparative anatomy
• Paleontology

Background:

• Platyrrhines (New World monkeys) are classified into three families: Cebidae, Atelidae, and Pitheciidae.
• Significant morphological variability exists within and between these platyrrhine families, prompting further investigation.
• Understanding molar shape variation is crucial for taxonomic and evolutionary insights.

Purpose of the Study:

• To analyze molar shape variability across extant platyrrhine species.
• To investigate patterns of interspecific variation in molar morphology.
• To assess the utility of molar shape as a taxonomic indicator in platyrrhines.

Main Methods:

• Geometric morphometric analysis of 802 platyrrhine lower molars.
• Application of standard multivariate statistical analyses.
• Comparison of molar shape data with existing phylogenetic frameworks.

Main Results:

• Interspecific variation in molar shape shows a homoplastic pattern, suggesting functional adaptations in certain taxa.
• Phylogenetic relationships also significantly influence molar morphology, with some similarities aligning with current classifications.
• The interplay between phylogenetic and functional signals in molar shape varies by platyrrhine taxon and specific tooth.

Conclusions:

• Lower molar shape in platyrrhines reflects a combination of evolutionary history and functional pressures.
• Convergent evolution, driven by similar dietary habits, can lead to superficial similarities in molar morphology (e.g., Aotus and Callicebus).
• Molar shape analysis provides valuable, albeit complex, data for understanding platyrrhine evolution and taxonomy.