Lystrosaurus Assemblage Zone
The Lystrosaurus Assemblage Zone is a tetrapod assemblage zone or biozone which correlates to the upper Adelaide and lower Tarkastad Subgroups of the Beaufort Group, a fossiliferous and geologically important geological Group of the Karoo Supergroup in South Africa. This biozone has outcrops in the south central Eastern Cape (Middelburg, Queenstown, Aliwal North, Nieu-Bethesda) and in the southern and northeastern Free State (Bethulie, Gariep Dam, Mthatha, Harrismith). The Lystrosaurus Assemblage Zone is one of eight biozones found in the Beaufort Group, and is considered to be Early Triassic in age.
| Lystrosaurus Assemblage Zone | |
|---|---|
| Stratigraphic range: Early Triassic ~ | |
Lystrosaurus murrayi | |
| Type | Biozone |
| Unit of | Beaufort Group within Adelaide Subgroup |
| Sub-units | Upper Balfour Formation west of 24°E Entire Katberg Formation east of 24°E |
| Underlies | Cynognathus Assemblage Zone |
| Overlies | Daptocephalus Assemblage Zone |
| Thickness | up to 2,723.1 feet (830 m) |
| Location | |
| Location | Karoo Basin |
| Region | Eastern Cape, Free State |
| Country | South Africa |
| Extent | Karoo Basin |
| Type section | |
| Named for | Lystrosaurus |
| Named by | Robert Broom |
| Year defined | 1906, 1909 |
The name of the biozone refers to Lystrosaurus, a small to medium-sized dicynodont therapsid. It is characterized by the appearance of further Lystrosaurus subspecies which are confined to this biozone. Lystrosaurus maccaigi and Lystrosaurus curvatus are the only two species found outside the Lystrosaurus Assemblage Zone in Upper Permian deposits of the underlying Daptocephalus Assemblage Zone.