Titolo della tesi: Applying cladistics to geometric morphometrics data: a new approach to resolve the phylogeny of the genus Homo.
This dissertation investigates hominin cranial evolution through an integrative analytical framework that combines discrete morphological data with geometric morphometrics (GMM) in cladistic analysis. Defining species in the fossil record remains a major challenge in palaeoanthropology, as reproductive isolation cannot be directly inferred from morphological evidence. Morphological evidence, therefore, remains the primary basis for reconstructing phylogenetic relationships, requiring rigorous methods to distinguish shared ancestry from convergent adaptation.
Traditional morphometric approaches quantify linear measurements but often overlook geometric relationships among traits. GMM addresses these limitations by capturing three-dimensional shape variation through landmark coordinates and multivariate statistical methods, providing a robust, reproducible framework for analysing cranial morphology. However, integrating continuous morphometric data into cladistic analysis presents challenges related to homology, dimensionality, and statistical dependence.
This research empirically assesses the use of GMM data in cladistics and their combination with discrete morphological matrices to clarify relationships among Australopithecus, Paranthropus, and early Homo taxa. Phylogenetic analyses were conducted under maximum parsimony using datasets of 23 and 28 operational taxonomic units. Robustness was assessed through bootstrap resampling and topological congruence metrics. Results demonstrate that raw landmark coordinates retain stronger phylogenetic signal than PCA-derived variables, and that integrating continuous and discrete datasets significantly improves node support and overall tree resolution.
The combined analyses resolve several key ambiguities, notably clarifying the internal structuring of Homo erectus sensu lato and supporting the monophyly of the robust australopiths (Paranthropus). Later hominins, including Homo neanderthalensis and H. sapiens, display stable, well-supported clades consistent with fossil and genomic evidence.
Overall, this work demonstrates that hominin evolution followed a branching trajectory shaped by geographic differentiation, ecological adaptation, and developmental plasticity. The integration of traditional and geometric morphometric approaches provides a more nuanced and statistically rigorous framework for reconstructing the complex evolutionary history of the genus Homo.