Manda Formation

Manda Formation
Stratigraphic range: Anisian? - Carnian? PreꞒ Ꞓ O S D C P T J K Pg N
Map of the outcropping Manda Formation
Type	Geological formation
Unit of	Songea Group
Sub-units	Kingori Sandstone Member, Lifua Member
Underlies	None
Overlies	Usili Formation
Lithology
Primary	Sandstone
Other	Mudstone, siltstone, marl
Location
Coordinates	10°18′S 35°12′E / 10.3°S 35.2°E / -10.3; 35.2
Approximate paleocoordinates	53°42′S 23°00′E / 53.7°S 23.0°E / -53.7; 23.0
Region	Iringa & Ruvuma Regions
Country	Tanzania
Extent	Ruhuhu Basin
Manda Formation (Tanzania)

The Manda Formation (also known as the Manda Beds) is a Middle Triassic (Anisian?) or possibly Late Triassic (Carnian?) geologic formation in Tanzania. It preserves fossils of many terrestrial vertebrates from the Triassic, including some of the earliest dinosauromorph archosaurs.^[1] The formation is often considered to be Anisian in age according to general tetrapod biochronology hypotheses and correlations to the Cynognathus Assemblage Zone of South Africa.^[2] However, some recent studies cast doubt to this age, suggesting that parts may actually be younger (Carnian) in age.^[3][4][5]

One of the first to study rocks of the Manda Formation was British geologist G. M. Stockley. In 1932, Stockley explored the geology of the Ruhuhu Basin in Tanzania. He called a series of layers dating from the Late Carboniferous to the Middle Triassic the Songea Series and divided it into eight units labelled K1-K8. Stockley was also the first to describe fossils from these rocks, naming an older layer the "Lower Bone Bed" and a younger layer the "Upper Bone Bed".

In 1957, paleontologist Alan J. Charig described many more fossils from the bone beds in his Ph.D. thesis for the University of Cambridge.^[6][7] Charig renamed the youngest of Stockley's units in 1963, calling unit K6 the Kawinga Formation, K7 the Kingori Sandstones, and K8 the Manda Formation. Fossils were identified in many strata, invalidating Stockley's division into two distinct bone beds. Since Charig's description, the Kawinga Formation has been renamed the Usili Formation, the Kingori Sandstones have become the Kingori Sandstone Member of the Manda Formation, and Charig's original Manda Formation has become a subunit of the formation called the Lifua Member.^[1] Six formations and one informal unit are currently recognized in the Songea Group (Ruhuhu basin) rocks range in age from Pennsylvanian to Anisian, including the Idusi (K1), Mchuchuma (K2), Mbuyura (K3), Mhukuru (K4), Ruhuhu (K5), and Usili (K6) formations and the informal Manda Beds, which include the Kingori Sandstone (K7) and Lifua Member (K8).^[8]

The upper Manda Beds have been assigned to the Perovkan LVF based on reports that Eryosuchus,^[9] Shansiodon,^[10] Angonisaurus, and Scalenodon^[11] were present.^[12] Angonisaurus does seem to tie the Manda Beds to subzone C of the Cynognathus Assemblage Zone in the Karoo Basin.^[13] However, the relations of the other Tanzanian taxa are more ambiguous. Purported Tanzanian "Eryosuchus" and "Shansiodon" specimens likely represent new genera unrelated to their supposed namesakes,^[14][13] while Scalenodon may be endemic to Africa due to the uncertain relations of non-African "Scalenodon" species.^[15] One Upper Manda cynodont, Aleodon, has also been found in the Dinodontosaurus assemblage zone of the Santa Maria Formation in Brazil.^[16]

The Lifua Member sandstone was deposited by rivers. Meandering, probably sandy rivers were present.^[17] In the middle to upper Lifua bone accumulations, evidence suggests "that ponds and springs were a much more common occurrence on the Ruhuhu Basin floodplains at this time than before or after"; the local climate likely became warmer and wetter then. The increase in water would have promoted perennial vegetation, which became diversity hotspots for tetrapods, resulting in more bones being deposited here.^[18]

Color key Taxon Reclassified taxon Taxon falsely reported as present Dubious taxon or junior synonym Ichnotaxon Ootaxon Morphotaxon		Notes Uncertain or tentative taxa are in small text; crossed out taxa are discredited.

Taxon	Species	Member	Material	Notes	Images
?Tihkia	?T. karrooensis[19]	Lifua[18]	Articulated specimens[18]	A freshwater bivalve, originally named as Unio karrooensis.[20] Also known from the Ntawere Formation.[19]

Color key Taxon Reclassified taxon Taxon falsely reported as present Dubious taxon or junior synonym Ichnotaxon Ootaxon Morphotaxon		Notes Uncertain or tentative taxa are in small text; crossed out taxa are discredited.

Taxon	Species	Member	Material	Notes	Images
Stanocephalosaurus	S. pronus[21]	Lifua		Remains of a temnospondyl amphibian previously referred either to Parotosuchus or Eryosuchus[22]

Taxon	Species	Member	Material	Notes	Images
Ruhuhuaria	R. reiszi[23]	Lifua	CAMZM T997, poorly preserved but complete skull and mandible	An owenettid

Taxon	Species	Member	Material	Notes	Images
Asperoris	A. mnyama	Lifua	NHMUK PV R36615, incomplete skull	A non-crurotarsan archosauriform of uncertain phylogenetic placement
"Stagonosuchus"	"S." tanganyikaensis[24]	Lifua Member	SAM 11754, right humerus	An indeterminate archosauromorph; possibly a rhynchosaur unrelated to Stagonosuchus nyassicus.
Stenaulorhynchus	S. stockleyi	Lifua		A rhynchosaur
Unnamed Archosauromorph[21]	Indeterminate.	Lifua	NHMUK PV R36619, incomplete skull and partial postcranial skeleton	A non-archosaurian archosauriform

Taxon	Species	Member	Material	Notes	Images
Asilisaurus	A. kongwe	Lifua	Several holotype specimens consist of a well-preserved, articulated partial skeleton and dentary	A silesaurid dinosauriform
Hypselorhachis	H. mirabilis	Lifua	NHMUK R16586, a complete dorsal vertebra	A sail-backed archosaur possibly belonging to the family Ctenosauriscidae
Mambawakale	M. ruhuhu[25]	Lifua	NHMUK R36620, partial skull and some postcranial fragments	A paracrocodylomorph; previously informally known as "Pallisteria angustimentum".
Mandasuchus	M. tanyauchen[26]	Lifua	NHMUK R6792, partial mandible and postcranial skeletons	A paracrocodylomorph
Nundasuchus	N. songeaensis[21][27]	Lifua	NMT RB48, partial skeleton and skull	A pseudosuchian of uncertain affinities, possibly a suchian
Nyasasaurus	N. parringtoni[2]	Lifua	NHMUK R6856, a right humerus, three partial presacral vertebrae and three sacral vertebrae. SAM-PK-K10654 is also potentially referable - see "Thecodontosaurus" alophos below.	A theropod or an ornithischian or the most advanced non-dinosaurian dinosauriform. Possibly the oldest dinosaur.[2]
Stagonosuchus	S. nyassicus	Lifua	Two individuals of different sizes mostly preserving postcranial elements	A large loricatan closely related to Prestosuchus, and sometimes considered a species within that genus.
Teleocrater	T. rhadinus	Lifua	NHMUK R6795, vertebrae, limb bones and other elements. Additional material referred from two other individuals.	An early avemetatarsalian in the group Aphanosauria.[28]
"Thecodontosaurus"	"T." alophos[2]	Lifua	SAM-PK-K10654, three neck vertebrae and two rear presacral vertebrae	A probable subjective senior synonym of Nyasasaurus, initially identified as a sauropodomorph dinosaur.[2]
Unnamed archosaur[29]	Unidentified.	Lifua	Nearly complete skull and partial skeleton	A stem-aetosaur

Taxon	Species	Member	Material	Notes	Images
Angonisaurus	A. cruickshanki	Lifua		A kannemeyeriiform
Kannemeyeria	K. simocephalus	Lifua		A kannemeyeriid kannemeyeriiform
Sangusaurus	S. parringtonii	Lifua		A stahleckeriid kannemeyeriiform
Shansiodon	Indeterminate	Lifua	Skull	A shansiodontid kannemeyeriiform
Tetragonias	T. njalilus	Lifua		A shansiodontid kannemeyeriiform

Taxon	Species	Member	Material	Notes	Images
Aleodon	A. brachyrhamphus	Lifua		A possible chiniquodontid
Cricodon	C. metabolus	Lifua		A trirachodontid
Cynognathus	C. crateronotus[30]	Lifua		A cynognathid
Diademodon	D. tetragonas	Lifua		A diademodontid
Scalenodon	S. angustifrons	Lifua		A traversodontid
	S? attridgei	Lifua		A traversodontid; may fall outside the genus Scalenodon and may be a synonym of "Scalenodon" charigi
	S? charigi	Lifua		A traversodontid; may fall outside the genus Scalenodon
Mandagomphodon	M. hirschoni	Lifua		A traversodontid; originally classified in the genus Scalenodon; named after the Manda Beds

• Geology of Tanzania
• Beaufort Group
• Omingonde Formation