Ntawere Formation

Ntawere Formation
Ntawere Formation
Stratigraphic range: Anisian; ~247–242 Ma PreꞒ Ꞓ O S D C P T J K Pg N ↓
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

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. Bibcode:2017JVPal..37S...8P. doi:10.1080/02724634.2017.1410484. ISSN 0272-4634. S2CID 133878741.