Primate tooth crown nomenclature revisited

Area of Science:

• Paleontology
• Primate Anatomy
• Evolutionary Biology

Background:

• Primate molar cusp patterns are vital for species identification, phylogenetic analysis, and reconstructing primate evolutionary history.
• Existing nomenclature systems for primate dental morphology struggle to account for the observed variation, particularly at the enamel-dentine junction (EDJ).
• Studies of the EDJ have revealed greater cusp variation in some primate taxa than current classification systems can accommodate.

Approach:

• Investigated mandibular crown morphology at the EDJ across major primate clades using microtomography.
• Reviewed current nomenclature systems for primate molar teeth and assessed their applicability.
• Documented and analyzed novel patterns of lower molar accessory cusp expression in primates.

Key Points:

• Observed significant discrepancies between expected cusp variation patterns from existing literature and new patterns identified at the EDJ.
• Identified numerous previously undocumented accessory cusp expressions on primate lower molars.
• Highlighted limitations of current nomenclature in describing the full spectrum of primate dental morphology.

Conclusions:

• Introduced a conservative, location-based naming scheme for new accessory cusp structures due to incomplete understanding of their developmental and phylogenetic origins.
• The proposed nomenclature offers a practical method for addressing these features in the absence of detailed developmental and evolutionary insights.
• Recommended cautious utilization of accessory cusp data in taxonomic and phylogenetic studies until further research clarifies their origins.