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16-586: 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 . The formation is often considered to be Anisian in age according to general tetrapod biochronology hypotheses and correlations to

32-678: A subunit of the formation called the Lifua Member. 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). The upper Manda Beds have been assigned to

48-647: Is an extinct taxon of diverse, aquatic reptiles that developed from terrestrial ancestors soon after the end-Permian extinction and flourished during the Triassic before all except for the Plesiosauria became extinct at the end of that period. The plesiosaurs would continue to diversify until the end of the Mesozoic . Sauropterygians are united by a radical adaptation of their pectoral girdle , adapted to support powerful flipper strokes. Some later sauropterygians, such as

64-1231: Is the result of an analysis of sauropterygian relationships (using just fossil evidence) conducted by Neenan and colleagues, in 2013. Pantestudines [REDACTED] † Kuehneosauridae [REDACTED] Lepidosauria [REDACTED] † Prolacertiformes [REDACTED] † Choristodera [REDACTED] † Rhynchosauria [REDACTED] † Trilophosaurus [REDACTED] Archosauriformes [REDACTED] † Ichthyopterygia [REDACTED] † Thalattosauria [REDACTED] † Eusaurosphargis † Hanosaurus [REDACTED] † Helveticosaurus † Sinosaurosphargis † Placodontiformes [REDACTED] † Yunguisaurus † Plesiosauria [REDACTED] † Pistosaurus [REDACTED] † Augustasaurus † Corosaurus † Cymatosaurus † Simosaurus † Germanosaurus † Nothosaurus [REDACTED] † Lariosaurus [REDACTED] † Diandongosaurus † Dianopachysaurus † Keichousaurus † Wumengosaurus † Anarosaurus - Dactylosaurus † Neusticosaurus - Serpianosaurus The cladogram shown below follows

80-710: The Cynognathus Assemblage Zone of South Africa . However, some recent studies cast doubt to this age, suggesting that parts deposits may actually be younger ( Carnian ) in age. 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

96-621: 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 . Charig renamed the youngest of Stockley's units in 1963, calling unit K6

112-514: The Permian–;Triassic extinction event , the most devastating of all mass-extinctions, life recovered slowly. In the Middle Triassic, many groups of organisms reached higher diversity again, such as the marine reptiles (e.g. ichthyosaurs , sauropterygians , thallatosaurs ), ray-finned fish and many invertebrate groups like molluscs ( ammonoids , bivalves , gastropods ). During

128-647: The Perovkan LVF based on reports that Eryosuchus, Shansiodon, Angonisaurus, and Scalenodon were present. Angonisaurus does seem to tie the Manda Beds to subzone C of the Cynognathus Assemblage Zone in the Karoo Basin . 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, while Scalenodon may be endemic to Africa due to

144-629: The plesiosaurs . During the Early Jurassic , these diversified quickly into both long-necked small-headed plesiosaurs proper, and short-necked large-headed pliosaurs . Originally, it was thought that plesiosaurs and pliosaurs were two distinct superfamilies that followed separate evolutionary paths. It now seems that these were simply morphotypes in that both types evolved a number of times, with some pliosaurs evolving from plesiosaur ancestors, and vice versa. Classification of sauropterygians has been difficult. The demands of an aquatic environment caused

160-413: The pliosaurs , developed a similar mechanism in their pelvis . It is possible that sauropterygians are a distant relatives of turtles , uniting them under the group Pantestudines , although this is still debatable as sauropterygians might be archosauromorphs or completely unrelated to both. The earliest sauropterygians appeared about 247 million years ago (Ma), at the start of the Middle Triassic :

176-653: 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

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192-460: The Middle Triassic, there were no flowering plants, but instead there were ferns and mosses. Small dinosauriforms began to appear, like Nyasasaurus and the ichnogenus Iranosauripus . This article related to the Triassic period is a stub . You can help Misplaced Pages by expanding it . This geochronology article is a stub . You can help Misplaced Pages by expanding it . Sauropterygians Sauropterygia (" lizard flippers ")

208-437: The beginning of the 2010s have suggested that they are more closely related to archosaurs (birds and crocodilians) than to lepidosaurs (lizards and snakes). Some authors have suggested that Sauropterygians form a clade with two other groups of marine reptiles, Ichthyosauromorpha and Thalattosauria , with this clade either being placed as non- saurian diapsids or as basal archosauromorphs . The cladogram shown hereafter

224-578: The first definite sauropterygian with exact stratigraphic datum lies within the Spathian division of the Olenekian era in South China. Early examples were small (around 60 cm), semi-aquatic lizard-like animals with long limbs ( pachypleurosaurs ), but they quickly grew to be several metres long and spread into shallow waters ( nothosaurs ). The Triassic-Jurassic extinction event wiped them all out except for

240-424: The same features to evolve multiple times among reptiles, an example of convergent evolution . Sauropterygians are diapsids , and since the late 1990s, scientists have suggested that they may be closely related to turtles . The bulky-bodied, mollusc-eating placodonts may also be sauropterygians, or intermediate between the classic eosauropterygians and turtles. Several analyses of sauropterygian relationships since

256-619: The uncertain relations of non-African " Scalenodon" species. One Upper Manda cynodont, Aleodon , has also been found in the Dinodontosaurus assemblage zone of the Santa Maria Formation in Brazil. Middle Triassic Formerly the middle series in the Triassic was also known as Muschelkalk . This name is now only used for a specific unit of rock strata with approximately Middle Triassic age, found in western Europe. Following

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