Paleoclimate and paleoecology of Miocene Eastern African primate habitats : a multiproxy approach.

Reconstructing Miocene climate and ecosystem in eastern Africa is essential for understanding the environmental and geological contexts in which early primates evolved. Particularly, correlations between leaf size, shape, temperature, and precipitation have become a widely used tool for paleoclimate and paleoecological inference. However, African floras remain underrepresented in global calibration datasets, limiting the accuracy of climate reconstructions. This dissertation addresses that gap by expanding the leaf physiognomic framework for tropical Africa and integrating it with stratigraphy, sedimentology, paleopedology, geochemistry, phytolith analyses, and vertebrate paleontology to refine environmental reconstructions at two key western Kenya localities: Early Miocene Koru 16 site of the Tinderet complex and Middle Miocene deposits of the Nyakach Formation. Modern African floras exhibit strong precipitation‑driven physiognomic patterns, with leaf area increasing with mean annual precipitation and tooth traits decreasing. Temperature plays a comparatively minor role, though entire‑margin frequency rises modestly with increasing mean annual temperature. African sites occupy a distinct morphospace within global datasets, and morphological dissimilarity among floras aligns closely with rainfall, highlighting weaker climate signals when African floras are combined with global samples. Phylogenetic effects are weak to moderate, emphasizing ecological adaptation over lineage constraints in paleoclimate reconstruction. At Koru 16, interbedded ash and weakly developed paleosols preserve fossil leaves, in situ stump casts, and vertebrates, enabling high‑resolution paleoenvironmental reconstructions. Leaf‑based proxies indicate a warm, humid tropical climate (MAT ~24 °C; MAP ~1,900–2,040 mm/yr). Leaf mass per area suggests a semi‑deciduous, spatially heterogeneous forest repeatedly disturbed by volcanism and fire. The vertebrate assemblage is consistent with closed‑canopy conditions. In the Nyakach Formation, discontinuous rift‑margin floodplain deposits record dynamic fluvial systems influenced by episodic volcanism. Smectite‑rich, base‑saturated paleosols and geochemical MAP estimates (~1,100–1,400 mm/yr), together with phytolith and δ¹³C evidence of predominantly C₃ vegetation with sparse C₄ grasses, indicate seasonally wet tropical forests with localized openings during the Miocene Climatic Optimum. Together, these results depict rifted, volcanically influenced, seasonally wet forest mosaics rather than a simple forest–savanna transition. The dissertation demonstrates the value of regionally based datasets and multiproxy integration, providing refined site‑ to basin‑scale environmental frameworks for Early–Middle Miocene primate habitats.

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Doctoral

Grantor

Baylor University.

Year dc:date.issued

2026

Author dc:creator

• Munyaka, Venanzio Njuguna, 1995-

Advisor dc:contributor.advisor

• Peppe, Daniel J.

• Paleoclimate.
• Leaf physiognomy.
• Hominoids.
• Miocene.
• Paleoecology.

Statement dc:rights

• Baylor University works are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. Contact libraryquestions@baylor.edu for inquiries about permission.

Language dc:language.iso

en

Handle dc:identifier.uri

https://hdl.handle.net/2104/14687

OAI identifier oai:identifier

oai:baylor-ir.tdl.org:2104/14687