Ntawere Formation
| Ntawere Formation | |
|---|---|
| Stratigraphic range: Anisian ~ | |
| Type | Geological formation |
| Sub-units | Lower Ntawere, Upper Ntawere |
| Underlies | Red Marls |
| Overlies | Escarpment Grit |
| Lithology | |
| Primary | Mudstone |
| Other | Sandstone, marl |
| Location | |
| Coordinates | 10°48′S 33°06′E / 10.8°S 33.1°E |
| Approximate paleocoordinates | 53°36′N 20°36′E / 53.6°N 20.6°E |
| Region | Eastern Province |
| Country |  Zambia |
| Extent | Luangwa Basin |
  Ntawere Formation (Zambia) | |
The Ntawere Formation is a Middle Triassic (Anisian) geological formation in Zambia, preserving fossils of synapsids, archosaurs, and temnospondyls.[1]
Geology
Several different facies are present in the Ntawere Formation, reconstructing a floodplain environment. The coarsest facies are trough cross-bedded conglomeratic sandstone full of mineral concretions. These coarse deposits formed in ancient channels such as riverbeds. Another type of facies involves thick beds of mudstone interbedding with thinner layers of fine-grained sandstone, indicating alternating low- and high-energy water flow within the channels. Graded sandstone to mudstone overbank deposits (complete with ripple marks) occur near channel deposits. Extensive successions of laminated or massive mudstone are common, often containing slickensides, calcareous nodules or layers (marls), and/or hematite nodules. These types of thick mud/marl layers likely formed in more quiet parts of the floodplain isolated from turbulent channels.[1]
The floodplain was seemingly more active during the deposition of the Lower Ntaware Formation, as coarser sandstone channel fills are prevalent in that section while extensive mudstone layers are more common in the Upper Ntaware Formation. Fossils are typically found preserved in calcareous nodules in the mudstone of the Upper Ntaware, although they occur in some parts of the Lower Ntaware as well. The Ntaware Formation is an example of red beds, which are typically deposited in warm environments with seasonal ponds and rivers tied to wet and dry seasons.[1]
Paleobiota
Invertebrates
| Invertebrates of the Ntawere Formation | ||||||
|---|---|---|---|---|---|---|
| Taxon | Member | Material | Notes | |||
| Unio karooensis | Upper Ntaware | Shells | A freshwater unionid bivalve | |||
Fish
| Fish of the Ntawere Formation | ||||||
|---|---|---|---|---|---|---|
| Taxon | Member | Material | Notes | |||
| Hybodontoidei indet. | Upper Ntaware | Fin spines | An indeterminate non-hybodontid hybodontoid shark, similar to Lissodus and Lonchidion | |||
| Ptycoceratodontidae indet. | Lower Ntaware, Upper Ntawere | Tooth plates | An indeterminate lungfish, similar to Ptychoceratodus | |||
Amphibians
| Amphibians of the Ntawere Formation | ||||||
|---|---|---|---|---|---|---|
| Taxon | Member | Material | Notes | Images | ||
| Batrachosuchus concordi | Upper Ntaware | A skull and forelimbs | A brachyopid stereospondyl |
  | ||
| Cherninia megarhina | Upper Ntaware | A partial skull | A mastodonsaurid stereospondyl | |||
| "Stanocephalosaurus" pronus | Upper Ntaware | A skull | A new species of capitosauroid, likely not part of the genus Stanocephalosaurus | |||
| Stereospondyli indet. | Upper Ntaware | Vertebrae and part of a jaw | Indeterminate stereospondyl material. The jaw fragment may belong to a rhinesuchid, lydekkerinid, or rhytidosteid | |||
Synapsids
| Synapsids of the Ntawere Formation | ||||||
|---|---|---|---|---|---|---|
| Taxon | Member | Material | Notes | Images | ||
| Cricodon metabolus | Upper Ntaware | A partial skeleton | A trirachodontid cynodont |
  | ||
| Cynognathus crateronotus | Lower Ntaware | Teeth, vertebrae, partial humerus, ilium | A cynognathian cynodont | |||
| Diademodon tetragonus | Lower Ntaware | A skull | A diademodontid cynodont | |||
| "Kannemeyeria" latirostris | Lower Ntaware | A skull | A kannemeyeriiform dicynodont, possibly a species of Kannemeyeria or Dolichuranus | |||
| Kannemeyeria lophorhinus | Lower Ntaware | A skull | A kannemeyeriid dicynodont | |||
| Luangwa drysdalli | Upper Ntaware | Skulls and postcranial material | A traversodontid cynodont | |||
| Sangusaurus edentatus | Upper Ntaware | A partial skull | A stahleckeriid dicynodont | |||
| Traversodontidae sp. | Upper Ntaware | Skulls and postcranial material | An unnamed species of gomphodont-like traversodontid cynodont | |||
| Zambiasaurus submersus | Upper Ntaware | A skull fragment | A stahleckeriid dicynodont | |||
Archosauromorphs
| Archosauromorphs of the Ntawere Formation | ||||||
|---|---|---|---|---|---|---|
| Taxon | Member | Material | Notes | Images | ||
| Archosauriformes indet. | Upper Ntaware | Teeth | Various indeterminate large carnivorous archosauriforms, likely loricatans |
 | ||
| Archosauromorpha indet. | Upper Ntaware | A neck vertebra | An indeterminate archosauromorph, possibly an allokotosaur | |||
| Dinosauriformes indet. | Upper Ntaware | A partial fibula | A large dracohortian, likely a silesaurid | |||
| Loricata indet. | Upper Ntaware | Vertebrae | An indeterminate large archosaur, similar to Stagonosuchus | |||
| Lutungutali sitwensis | Upper Ntaware | An ilium | A basal silesaurid | |||
| Shuvosauridae indet. | Upper Ntaware | Part of a femur | An indeterminate shuvosaurid archosaur similar to Shuvosaurus and the indeterminate "Moenkopi poposauroid" | |||
| Silesauridae indet. | Upper Ntaware | A maxilla, femurs, and material from the hip, ankle, and foot | Indeterminate basal silesaurid material comparable to Asilisaurus and Lutungutali | |||
See also
- Donguz Formation, contemporaneous fossiliferous formation of Russia
- Ermaying Formation, contemporaneous fossiliferous formation of China
- Manda Formation, contemporaneous fossiliferous formation of Tanzania
- Omingonde Formation, contemporaneous fossiliferous formation of Namibia
- Río Seco de la Quebrada Formation, contemporaneous fossiliferous formation of Argentina
- Yerrapalli Formation, contemporaneous fossiliferous formation of India
References
- ^ a b c Peecook, Brandon R.; Steyer, J. Sébastien; Tabor, Neil J.; Smith, Roger M. H. (2017-11-29). "Updated geology and vertebrate paleontology of the Triassic Ntawere Formation of northeastern Zambia, with special emphasis on the archosauromorphs". Journal of Vertebrate Paleontology. 37 (sup1): 8–38. doi:10.1080/02724634.2017.1410484. ISSN 0272-4634. S2CID 133878741.
Further reading
- K. D. Angielczyk, J. S. Steyer, C. A. Sidor, R. H. H. Smith, R. L. Whatley and S. Tolan. 2014. Permian and Triassic Dicynodont (Therapsida: Anomodontia) Faunas of the Luangwa Basin, Zambia: Taxonomic Update and Implications for Dicynodont Biogeography and Biostratigraphy. In C. F. Kammerer, K. D. Angielczyk and J. Fröbisch (eds.), Early Evolutionary History of the Synapsida 93-138
- A. R. Drysdall and J. W. Kitching. 1963. A re-examination of the Karroo succession and fossil localities of part of the Upper Luangwa Valley. Memoir of the Geological Survey of Northern Rhodesia 1:1-62