The next spring 2015 Leakey Foundation grantee we would like to introduce you to is Gabrielle Russo from Stony Brook University. Her project is entitled “Elucidating the evolutionary pathways of hominin basicranial morphology using a formal phylogenetic comparative primate approach.”
Gabrielle Russo (R) and collaborator Jeroen B. Smaers
The morphology of the basicranium (base of the skull) in modern humans is distinct from that in our closest living relatives and has therefore been a central focus for paleoanthropologists seeking to understand the evolutionary pathways that led from the panin (chimpanzees and bonobos) – hominin last common ancestor to Homo sapiens.
The basicranium is typically studied using a ‘fossil to living’ approach, in which one or few features preserved for fossil hominin crania are evaluated in a hominid-centric sample in order to identify features that are primitive to hominids, derived and shared among hominins, or unique to modern humans. However, a burgeoning Mio-Pliocene fossil record and recent interpretations of the Ardipithecus ramidus skeleton highlight the potential for mosaicism and independent evolution to complicate hypotheses about evolutionary relationships.
Our study addresses this issue by generating a broad perspective of basicranial evolution that formally combines information about the taxonomic breadth (110 living species) of basicranial morphological variation with the evolutionary depth (46 million years of primate evolution) of lineage-specific patterns of morphological change. Specifically, we employ a phylogenetically-integrated approach to quantify evolutionary changes in basicranial morphology within the Haplorhini, identify the patterns and processes of change responsible for select external cranial base features that are relevant to discussions of probable early hominins, and evaluate the extent to which certain factors (e.g., locomotion, brain size) explain the observed evolutionary patterns of basicranial morphology.
Our results will provide a critical first step toward contextualizing morphological variation among living primate species within a macroevolutionary framework that reveals detailed patterns of change over time. This approach will allow recognition of how patterns of change in basicranium morphology observed in recent hominin and great ape evolution relate to those that occurred elsewhere in phylogenetic space.