New approaches in hominoid taxonomy: morphometrics

Area of Science:

• Primatology
• Paleoanthropology
• Morphometrics

Background:

• Hominoid taxonomy relies on morphological and genetic data.
• Understanding variation within and between hominoid taxa is crucial for taxonomic analyses.

Purpose of the Study:

• To assess the discriminative power of maxillofacial complex shape in hominoid taxonomy.
• To evaluate the relevance of morphologic criteria for discriminating living hominoid species and subspecies.
• To provide a reference for morphological differentiation in the hominin fossil record.

Main Methods:

• Geometric morphometrics applied to 438 nonhuman hominoid skulls from 13 taxa.
• Selection of 19 landmarks to describe maxillofacial complex shape.
• Relative warp analysis to depict morphological variation from genus to subspecific level.

Main Results:

• The relative warp method using facial landmarks effectively discriminates taxa down to the subspecific level.
• Significant divergence observed within Pan species (chimpanzees).
• Morphological distances between gorilla populations and orangutan subspecies are comparable to interspecific distances within Pan.
• Intergeneric differences (Hylobates vs. Symphalangus) are similar to intergeneric differences (Pan vs. Gorilla).

Conclusions:

• Geometric morphometrics provides a powerful tool for hominoid taxonomic analysis.
• Morphological distances align with previous genetic and morphological studies, supporting their relevance for species recognition.
• The findings offer an objective standard for assessing taxonomic differences in living and fossil hominoids.