EOCENE (46 MA) RAINFALL ESTIMATES FOR TROPICAL EAST AFRICA BASED ON FOSSIL LEAVES FROM MAHENGE, TANZANIA

Middle Eocene paleoprecipitation estimates provided here are the only quantitative climate data points for the Paleogene of Africa, and have significance for paleoclimate modeling. A paleovegetation reconstruction aids in understanding the origins of tropical ecosystems. Paleoprecipitation is estimated using regression equations derived from leaf morphological data and climate parameters for modern low-latitude species assemblages. Fossil leaves from the Mahenge paleontological site in north-central Tanzania estimate mean annual precipitation at 536 to 731 mm/yr, near modern, and wet seasonal precipitation at 437 to 451 mm, supporting absence of monsoon circulation and wetter dry seasons than today. The plant community, primarily legumes, documents woodland structurally comparable to modern miombo, which is inconsistent with previously hypothesized lowland rainforest at 12°S paleolatitude.