| 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 |
| Coordinates | 32°00′S 25°30′E / 32.0°S 25.5°E |
| Approximate paleocoordinates | 65°48′S 22°06′W / 65.8°S 22.1°W |
| 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 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.[1][2]
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.[3] 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.[4][5]
- ^ Keyser, A. W., & Smith, R. M. H. (1978). Vertebrate biozonation of the Beaufort Group with special reference to the western Karoo Basin. Geological Survey, Department of Mineral And Energy Affairs, Republic of South Africa.
- ^ Rubidge, B. S. (ed.) 1995b. Biostratigraphy of the Beaufort Group (Karoo Supergroup). South African Committee of Stratigraphy. Biostratigraphic Series 1. Pretoria, Council for Geoscience.
- ^ Lucas, Spencer G. (2009-11-02). "Timing and magnitude of tetrapod extinctions across the Permo-Triassic boundary". Journal of Asian Earth Sciences. 36 (6): 491–502. Bibcode:2009JAESc..36..491L. doi:10.1016/j.jseaes.2008.11.016. ISSN 1367-9120.
- ^ Smith, R.M.H. (1995-08-01). "Changing fluvial environments across the Permian-Triassic boundary in the Karoo Basin, South Africa and possible causes of tetrapod extinctions". Palaeogeography, Palaeoclimatology, Palaeoecology. 117 (1–2): 81–104. Bibcode:1995PPP...117...81S. doi:10.1016/0031-0182(94)00119-S. ISSN 0031-0182.
- ^ BOTHA, JENNIFER; SMITH, ROGER M. H. (2007-04-08). "Lystrosaurus species composition across the Permo-Triassic boundary in the Karoo Basin of South Africa". Lethaia. 40 (2): 125–137. doi:10.1111/j.1502-3931.2007.00011.x. ISSN 0024-1164.