The Mahenge Formation is a

Middle Eocene The Eocene ( ) is a geological epoch that lasted from about 56 to 33.9 million years ago (Ma). It is the second epoch of the Paleogene Period in the modern Cenozoic Era. The name ''Eocene'' comes from the Ancient Greek (''Ēṓs'', ' Dawn') a ...

-aged

geological formation A geological formation, or simply formation, is a body of rock having a consistent set of physical characteristics (lithology) that distinguishes it from adjacent bodies of rock, and which occupies a particular position in the layers of rock expo ...

and '' Konservat-Lagerstätte'' from

Tanzania Tanzania, officially the United Republic of Tanzania, is a country in East Africa within the African Great Lakes region. It is bordered by Uganda to the northwest; Kenya to the northeast; the Indian Ocean to the east; Mozambique and Malawi to t ...

. It contains a high variety of exceptionally-preserved fossils, including many of the earliest fossil records of dominant freshwater fish groups found in Africa today. It represents one of the most comprehensive

Paleogene The Paleogene Period ( ; also spelled Palaeogene or Palæogene) is a geologic period and system that spans 43 million years from the end of the Cretaceous Period Ma (million years ago) to the beginning of the Neogene Period Ma. It is the fir ...

-aged African fossil deposits south of the Sahara. Based on fossil plant remains found in the formation, the Mahenge lake was situated within

legume Legumes are plants in the pea family Fabaceae (or Leguminosae), or the fruit or seeds of such plants. When used as a dry grain for human consumption, the seeds are also called pulses. Legumes are grown agriculturally, primarily for human consum ...

-dominated woodlands reminiscent of modern ''

miombo Miombo woodland is a tropical and subtropical grasslands, savannas, and shrublands biome (in the World Wide Fund for Nature scheme) located in central and southern tropical Africa. It includes three woodland savanna ecoregions (listed below) chara ...

'' forests. It was deposited within a former maar lake formed from a volcanic intrusion into the Precambrian bedrock via a

kimberlite pipe Volcanic pipes or volcanic conduits are subterranean geological structures formed by the violent, supersonic eruption of deep-origin volcanoes. They are considered to be a type of '' diatreme''. Volcanic pipes are composed of a deep, narrow cone o ...

. It has been dated to the

Lutetian The Lutetian is, in the geologic timescale, a stage (stratigraphy), stage or age (geology), age in the Eocene. It spans the time between . The Lutetian is preceded by the Ypresian and is followed by the Bartonian. Together with the Bartonian it ...

, roughly 46.0 million years ago. Unusually, relatively few fossil insect remains are known from the lake, unlike with other maar deposits. It is thought that the high diversity of fish in the lake may have led to most insects being consumed before they could be fossilized.

Paleobiota

Bony fish

Amphibians

Mammals

Insects

Plants

References

{{Reflist Geologic formations of Tanzania Paleontology in Tanzania Lutetian Stage Lacustrine deposits Eocene Series of Africa