Tendaguru Formation

The Tendaguru Formation represents the oldest sedimentary unit in the Mandawa Basin, directly overlying Neoproterozoic basement consisting of gneiss. The contact contains a large hiatus, a missing sequence of stratigraphy, spanning the Paleozoic, Triassic and Early Jurassic. The formation is unconformably overlaid by late Early Cretaceous sediments of the Makonde Formation that forms the top of several plateaus; Namunda, Rondo, Noto, and Likonde-Kitale. Based on extended geological and paleontological observations, the "Tendaguruschichten" (Tendaguru Beds) were defined by Werner Janensch as expedition leader and Edwin Hennig in 1914 referring to a sequence of Late Jurassic to Early Cretaceous strata, exposed in the Tendaguru area, which is named after the Tendaguru Hill. Stratigraphy The Tendaguru is divided into 6 members, which represent different depositional environments, with the 'Dinosaur Beds' representing terrestrial facies while the beds with genus/species names represent marine interbeds with shallow marine to lagoonal facies. In ascending order these are: the Lower Dinosaur Member, the Nerinella Member, the Middle Dinosaur Member, Indotrigonia africana Member, the Upper Dinosaur Member, and the Rutitrigonia bornhardti-schwarzi Member. The units of the Tendaguru are known to interfinger with each other. Paleogeography and depositional environment Paleogeography with S1. The Tendaguru Formation was deposited in the Mandawa Basin, a post-Karoo, Mesozoic rift basin located between the Ruvu Basin and Rufiji Trough to the north and the Ruvuma Basin to the south. To the west of the basin, Archean and Early Proterozoic basement rocks crop out. The main rift phase in present-day southeastern Africa led to the separation of Madagascar and the then-connected Indian subcontinent that happened during the Early Cretaceous. The Songo Songo and Kiliwani gas fields are located just offshore the basin. At time of deposition the area was undergoing a semi-arid climate with coastal influences that maintained somewhat higher moisture levels than seen inland. The upper parts of the formation, the Middle Dinosaur and Rutitrigonia bornhardti-schwarzi Members in particular, showed prevailing semiarid conditions with pronounced dry seasons, based on palynologic analysis. The Tendaguru fauna was stable through the Late Jurassic. During the Late Jurassic and Early Cretaceous, the Gondwana paleocontinent was breaking up and the separation of the Laurasian and Gondwana supercontinents resulted from the connection of the Tethys Ocean with the proto-Atlantic and the Pacific Ocean. In addition, the South Atlantic developed towards the end of the Late Jurassic with the separation of South America and Africa. Africa became increasingly isolated from most other continents by marine barriers from the Kimmeridgian into the Early Cretaceous, but retained a continental connection with South America. Global sea levels dropped significantly in the Early Jurassic and remained low through the Middle Jurassic but rose considerably towards the Late Jurassic, deepening the marine trenches between continents. Depositional environment The sedimentary rocks and fossils record a repeated shift from shallow marine to tidal flat environments indicating that the strata of the Tendaguru Formation were deposited near an oscillating strandline which was controlled by sea level changes. The three dinosaur-bearing members are continental to marginal marine and the three sandstone-dominated members are marginal marine in origin. ;Nerinella Member The composition of benthic molluscs and foraminifera, euhaline to mesohaline ostracods, and dinoflagellate assemblages indicate marine, shallow water conditions for the Nerinella Member, in particular for the lower part. Sedimentation occurred as tidal channel fills, subtidal and tidal sand bars, minor storm layers (tempestites), and beach deposits. Overall, the Nerinella Member represents a variety of shallow subtidal to lower intertidal environments influenced by tides and storms. ;Middle Dinosaur Member The sedimentological characteristics of the basal part of the Middle Dinosaur Member suggest deposition on tidal flats and in small tidal channels of a lagoonal paleoenvironment. The ostracod Bythocypris sp. from the member indicates polyhaline to euhaline conditions. Slightly higher up, a faunal sample dominated by the bivalve Eomiodon and an ostracod assemblage composed of brackish to freshwater taxa is indicative of a brackish water paleoenvironment with distinct influx of freshwater as revealed by the nonmarine ostracod genus Cypridea, charophytes, and other freshwater algae. The paleoenvironment of the ostracod assemblages of the Middle Dinosaur Member changed upsection from a marine setting in the basal parts through alternating marine-brackish conditions to freshwater conditions in the higher parts of this member. The presence of crocodyilforms indicates freshwater to littoral environments and adjacent terrestrial areas. ;Indotrigonia africana Member The coarse-grained sandstone of the lower part of the Indotrigonia africana Member that shows highly variable transport directions is interpreted as deposits of large tidal channels. Grain-size, large-scale sedimentary structures, and the lack of both trace fossils and epifaunal and infaunal body fossils suggest high water energy and frequent reworking. This basal succession passes upward in cross-bedded sandstone and minor siltstone and claystone with flaser or lenticular bedding that are interpreted as tidal flat and tidal channel deposits. Horizontal to low-angle cross-bedded, fine-grained sandstone with intercalated bivalve pavements indicates tidal currents that operated in small flood and ebb tidal deltas and along the coast. Stacked successions of trough cross-bedded, medium- to coarse-grained sandstone of the upper part of the Indotrigonia africana Member are interpreted as tidal channel and sand bar deposits. At some places in the surroundings of Tendaguru Hill, these sediments interfinger with oolitic limestone layers that represent high-energy ooid shoals. In the Tingutinguti stream section, the Indotrigonia africana Member exhibits several up to thick, poorly sorted, conglomeratic sandstone beds. They contain mud clasts, reworked concretions and/or accumulations of thick-shelled bivalves (mainly Indotrigonia africana and Seebachia janenschi), and exhibit megaripple surfaces. These conglomeratic sandstone layers are interpreted as storm deposits. In the Dwanika and Bolachikombe stream sections, and in a small tributary of the Bolachikombe creek, a discrete, up to thick conglomerate in the lower portion of the Indotrigonia africana Member displays evidence of a tsunami deposit. Overall, lithofacies and the diverse macroinvertebrate and microfossil assemblages of the Indotrigonia africana Member suggest a shallow marine environment. Based on the diverse mesoflora and the abundance of Classopollis, a nearby vegetated hinterland is postulated that was dominated by xerophytic conifers. ;Upper Dinosaur Member The small-scale trough and ripple cross-bedded fine-grained sandstone at the base of the Upper Dinosaur Member is interpreted as tidal flat deposits. Unfossiliferous sandstone in the upper part was most likely deposited in small fluvial channels in a coastal plain environment, whereas argillaceous deposits were laid down in still water bodies such as small lakes and ponds. Rare occurrences of the ostracod Cypridea and charophytes signal the influence of freshwater, whereas the sporadic occurrence of marine invertebrates suggests a depositional environment close to the sea. ;Rutitrigonia bornhardti-schwarzi Member Fining upward sequences of the basal part of the Rutitrigonia bornhardti-schwarzi Member are interpreted as tidal channel fills, the overlying fine-grained sandstone, silt- and claystone as tidal flat deposits. From the immediate surroundings of Tendaguru Hill, invertebrates and vertebrates are poorly known and limit the palaeoenvironmental interpretation of this member. The composition of the land-derived sporomorph assemblage suggests a terrestrial vegetation which was dominated by cheirolepidiacean conifers in association with ferns. == Excavation history ==

The Tendaguru Beds as a fossil deposit were first discovered in 1906, when German pharmacist, chemical analyst and mining engineer Bernhard Wilhelm Sattler, on his way to a mine south of the Mbemkure River in German East Africa in today's Tanzania, was shown by his local staff enormous bones weathering out of the path near the base of Tendaguru Hill, south of Mtapaia (close to Nambiranji village, Mipingo ward, northwest of Lindi town). Because of its morphology, the hill was locally known as "steep hill" or "tendaguru" in the language of the local Wamwera people. Sattler forwarded his report on the giant bones to the Kommission für die landeskundliche Erforschung der deutschen Schutzgebiete ("Commission for the Geographical Investigation of the German Protectorates"), headed by the geographer Hans Meyer. Meyer, in turn, wrote to the palaeontologist Eberhard Fraas, who was in East Africa at that time, and urged him to hasten to the Tendaguru site. The latter visited the site in 1907 and, with the aid of Sattler, recovered two partial skeletons of enormous size. Following the discovery in 1906, teams from the Museum für Naturkunde, Berlin (1907–1913), and later the British Museum (Natural History), London (1924–1931) launched a series of collecting expeditions that remain unequalled in scope and ambition. Led by the vision and influence of geologist Wilhelm von Branca, the German expeditions were particularly successful. This was largely due as the project was regarded as a matter of national ambition of the German Empire and enjoyed the benevolence of wealthy patrons. Eventually, nearly 250 tons of fossils were shipped to Berlin, representing an entirely new dinosaur fauna that remains the best understood assemblage from all of former Gondwana. From there, the material was transported to Fraas' institution, the Royal Natural History Collection in Stuttgart, Germany. Fraas described two species in the badly known genus "Gigantosaurus"; G. robustus and G. africanus (today Janenschia robusta and Tornieria africana, respectively. In popular culture In 1998, an illustrated book in Swahili, whose title translates as Dinosaurs of Tendaguru, was published for young readers in East Africa. It presents a slightly different, fictitious story of the first discovery, which is attributed to a Tanzanian farmer, rather than to the German engineer Sattler. == Paleontological significance ==

Possible dinosaur eggs have been recovered from the formation. Further, the fauna of the Tendaguru Formation has been correlated with the Morrison Formation of the central-western United States, several formations in England, such as the Kimmeridge Clay and Oxford Clay, and in France (Sables de Glos, Argiles d'Octeville, Marnes de Bléville), the Alcobaça, Guimarota and Lourinhã Formations in Portugal, the Villar del Arzobispo Formation in Spain, the Shishugou, Kalazha and Shangshaximiao Formations in China, the Toqui Formation in the Magallanes Basin, Chile and the Cañadón Calcáreo Formation in the Cañadón Asfalto Basin in central Patagonia, Argentina. Fossil content Mammaliaformes Squamates Pterosaurs Ornithischians Sauropods Theropods Crocodyliformes Amphibians Fish Invertebrates Gastropods Bivalves Coral Ostracods Flora == See also ==

Notes References Bibliography ;Geology • Material was copied from this source, which is available under a Creative Commons Attribution 4.0 International License. • Material was copied from this source, which is available under a Creative Commons Attribution 4.0 International License. • ;Paleontology • Material was copied from this source, which is available under a Creative Commons Attribution 4.0 International License. • • • • • Material was copied from this source, which is available under a Creative Commons Attribution 4.0 International License. • • • • • • • • • • • • • • • • • • • •