Usili Formation
| Usili Formation | |
|---|---|
| Stratigraphic range: Lopingian ~ | |
| Type | Geological formation |
| Unit of | Songea Group |
| Underlies | Manda Formation |
| Overlies | Ruhuhu Formation |
| Thickness | 260 m (850 ft) |
| Lithology | |
| Primary | Sandstone, conglomerate |
| Other | Siltstone, mudstone |
| Location | |
| Coordinates | 10°18′S 35°06′E / 10.3°S 35.1°E |
| Approximate paleocoordinates | 55°06′S 15°12′E / 55.1°S 15.2°E |
| Region | Ruvuma Region |
| Country | Tanzania |
| Extent | Ruhuhu Basin |
| Type section | |
| Named for | Usili Mountain |
| Named by | Stockley |
| Year defined | 1932 |
The Usili Formation is a Late Permian geologic formation in Tanzania. It preserves fossils of many terrestrial vertebrates from the Permian, including temnospondyls, pareiasaurs, therapsids and the archosauromorph Aenigmastropheus.