Molar size and shape variations among Asian colobines

Area of Science:

• Primatology
• Paleontology
• Comparative Anatomy

Background:

• Limited knowledge exists on Asian colobine dental morphometrics.
• Third molar (M3) features, like the hypoconulid, are often cited as genus-specific but lack comprehensive study.

Purpose of the Study:

• To document size and shape variations in third molars across eight Asian colobine genera.
• To quantify molar length differences and assess the occlusal impact of the hypoconulid.
• To understand the evolutionary and adaptive significance of dental morphology in Asian colobines.

Main Methods:

• Conducted an extensive survey of Asian colobine dentition.
• Analyzed continuous and categorical variables using descriptive statistics, chi-square, and t-tests.
• Performed post hoc comparisons to identify significant differences within and among genera.

Main Results:

• Species of Presbytis exhibit significant differences in maxillary and mandibular third molar size and shape compared to other Asian colobines.
• Presbytis M3 is shorter and less likely to have an occlusal hypoconulid.
• Presbytis also shows unique maxillary third molar features, including absence of a distal shelf and/or a separated distal cusp.

Conclusions:

• Dental morphometric variations, particularly in third molars, distinguish Presbytis from other Asian colobine taxa.
• These craniodental differences likely reflect variations in body size, dietary adaptations, and phylogenetic divergence.
• Further research into Asian colobine dental morphology can illuminate evolutionary pathways and ecological specializations.