Rift dynamics and primate evolution at the close of the Paleogene: A view from the Rukwa Rift Basin

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This project is a paleontological investigation to understand how primates and other organisms responded to dramatic environmental changes approximately 25 million years ago in Africa. The primary goals are to characterize a newly discovered fauna, find additional fossil-bearing localities, and conduct geological analyses to document the precise age and environmental setting for each locality. Fossils from this critically under-sampled temporal and geographic setting, including some of the earliest evidence of ape species, fill a gap in the evolutionary record and make it possible to test hypotheses regarding the sequence, timing and ecological context of primate evolution and biotic transitions. The project includes an interdisciplinary research team to mentor early-career scientists and provide hands-on field and laboratory research opportunities for undergraduate and graduate students, including females and students from underrepresented groups in STEM research. Results will be disseminated via conference presentations and publications in international journals, seminars for general audiences, symposia/workshops, interactive science outreach websites, museum exhibits, and K-12 learning activities.The study area for this project records an important window into Late Oligocene African terrestrial ecosystems, yielding the oldest specimens documenting the cercopithecoid-hominoid divergence. Near the Oligo-Miocene boundary, collision between Afro-Arabia and Eurasia resulted in large-scale faunal turnover, with eventual replacement of much of Africa's resident biota by invasive species. This altered the landscape of predation and competition, with profound implications for biodiversity. This project hypothesizes that key shifts in primate community composition were already occurring on the African continent prior to the Oligo-Miocene transition. Recent discoveries suggest that early hominoid and cercopithecoid evolution in eastern Africa took place against the backdrop of previously unrecognized tectonic activity in the western branch of the East African Rift System, coinciding with the global late Oligocene warming event, and pre-dating larger-scale faunal shifts that intensified later in the Miocene. These hypotheses will be tested using data collected from 400 m of geological section containing a diverse array of flora and fauna, with intercalated volcanic deposits providing age-constraint. Research methodologies integrate specimen-based microscopy, micro-CT techniques, morphometric and phylogenetic studies, together with geological analyses to document ecological setting and geochronology of the study sites.