Elliot Formation | |
---|---|
Stratigraphic range: Norian-Pliensbachian ~ | |
Type | Geological formation |
Unit of | Stormberg Group |
Sub-units | Upper Elliot, Lower Elliot |
Underlies | Clarens Formation |
Overlies | Molteno Formation |
Thickness | up to 500 m (1,600 ft) |
Lithology | |
Primary | Mudstone, sandstone |
Other | Siltstone, conglomerate |
Location | |
Coordinates | 30°30′S27°24′E / 30.5°S 27.4°E |
Approximate paleocoordinates | 44°06′S1°54′W / 44.1°S 1.9°W |
Region | Eastern Cape, Free State, Mafeteng, Maseru, Quthing, Qacha's Nek & Mohale's Hoek |
Country | Lesotho South Africa |
Type section | |
Named for | Elliot, Eastern Cape |
The Elliot Formation is a geological formation and forms part of the Stormberg Group, the uppermost geological group that comprises the greater Karoo Supergroup. Outcrops of the Elliot Formation have been found in the northern Eastern Cape, southern Free State, and in the eastern KwaZulu-Natal provinces of South Africa. Outcrops and exposures are also found in several localities in Lesotho such as Qacha's Neck, Hill Top, Quthing, and near the capital, Maseru. The Elliot Formation is further divided into the lower (LEF) and upper (UEF) Elliot formations to differentiate significant sedimentological differences between these layers. The LEF is dominantly Late Triassic (Norian-Hettangian) in age while the UEF is mainly Early Jurassic (Sinemurian-Pliensbachian) and is tentatively regarded to preserve a continental record of the Triassic-Jurassic boundary in southern Africa. [1] This geological formation is named after the town of Elliot in the Eastern Cape, and its stratotype locality is located on the Barkly Pass, 9 km north of the town. [2] [3] [4]
The Elliot Formation unconformably overlies the Molteno Formation and is conformably overlain by the Clarens Formation. Due to the reddish colour of the rocks, the Elliot Formation is colloquially referred to as the “Red Beds” in older geologic literature.
The Elliot Formation is dominated by mudstones and siltstones that can be finely laminated. However, the internal structures in the mudstones are often not visible due to locally poor laminations. Calcareous nodules are also found in the mudstone layers and become more frequent up section into the UEF. The mudstones range in colour from greyish purple red in the LEF and turn a more brick red colour with more mature palaeosols in the UEF. Localized intraformational pebble conglomerates that comprise intrabasinal clasts that comprise mud chips, quartzite pebbles, pedogenic nodules, and fossil bone fragments only occur in the UEF. The lower and upper Elliot formations both contain sandstones but they vary in their internal geometries. The sandstones of the LEF mainly comprise laterally accreting channel deposits that are multi-story and contain trough, low angle, and planar, cross-bedding. Ripple cross laminations with good horizontal lamination are also present. In the UEF, sandstone beds are single story and mainly reflect downstream accretion channel geometries and are more tabular in appearance. Common internal sedimentary structures of UEF sandstones are planar, low angle cross-bedding, horizontal and ripple-cross laminations.
The LEF was deposited in a fluvio-lacustrine environment where rivers were more perennial and formed meandering channel geometries, as evidenced by the presence of lateral accretion. However, this depositional environment changed at the onset of the UEF deposits where evidence of shallower river channels, longer periods of floodplain stasis (mature palaeosols) and flash flood events (pedogenic nodule conglomerates) shows that the climate became more arid. [5] [6] [7] [8]
The Elliot Formation is currently considered to correlate chronostratigraphically with geological formations of the Bodibeng Sandstone of the Tuli Basin in Botswana, the Omingonde Formation of the Etjo Basin in Namibia, and the Chinle Formation of the Colorado Plateau in Utah, United States. [9] [10] [11] [12] [13] [14]
The Elliot Formation is well known for its diverse dinosaur fossils. The most common dinosaur species is of the sauropodomorph species Massospondylus carinatus . [15] [16] Other species include Blikanasaurus cromptoni , Aardonyx celestae , Euskelosaurus browni , Antetonitrus ingenipes , Pulanesaura eocollum , and the largest sauropodomorph yet found, Ledumahadi mafube . [17] [18] [19] [20] [21] [22] [23] [24] Fossilised Massospondylus eggs, some with the fossilized remains of embryos intact, have been recovered from UEF deposits in the Golden Gate Highlands National Park. [25] [26] Euskelosaurus fossils are more common in the LEF while Massospondylus are only found in the UEF. The basal ornithischian dinosaurs, Heterodontosaurus tucki , Lesothosaurus diagnosticus , Abrictosaurus consors , and Lycorhinus angustidens have also been recovered from the UEF. [27] [28] In addition this formation has yielded various crocodylomorph species, [29] namely Litargosuchus leptorhynchus , Sphenosuchus acutus and Orthosuchus stormbergi . [30] [31] [32] [33] A large theropod dinosaur, Dracovenator regenti , has been found in the UEF. [34] Synapsids from the formation include the dicynodont Pentasaurus goggai [35] the tritheledontid cynodont Elliotherium kersteni [36] [37] and the mammaliaform Megazostrodon rudnerae . [38] More recent vertebrate fossil finds near the town Qhemegha in the Eastern Cape have yielded possible fossil material of a poposauroid pseudosuchian. The mudstones of the LEF sometimes yield petrified wood, fossil plant matter, crustaceans, fishes, and turtles while the sandstones of the upper Elliot Formation more often contain various trace fossils. These include vertebrate trackways of basal ornithischian dinosaurs found in the Leribe, Mafeteng, and Mohales Hoek Districts of Lesotho. Possible trackways of the dicynodont Pentasaurus have been found on Morobong Hill in the Mohales Hoek District of Lesotho. [39] [40] [41] [42]
Color key
| Notes Uncertain or tentative taxa are in small text; |
Ornithischians of the Elliot Formation | |||||
---|---|---|---|---|---|
Genus | Species | Location | Stratigraphy | Notes | Images |
Abrictosaurus | A. consors |
| A heterodontosaurid, formerly species of Lycorhinus | ||
Eocursor | E. parvus |
| A basal ornithischian | ||
Fabrosaurus | F. australis |
| A basal ornithischian, nomen dubium | ||
Heterodontosaurus | H. tucki |
| A heterodontosaurid | ||
Lesothosaurus | L. diagnosticus |
| A basal neornithischian or thyreophoran, formerly species of Fabrosaurus | ||
Lycorhinus | L. angustidens |
| A heterodontosaurid | ||
Pegomastax | P. africana |
| A heterodontosaurid | ||
Sauropodomorphs of the Elliot Formation | |||||
---|---|---|---|---|---|
Genus | Species | Location | Stratigraphy | Notes | Images |
Aardonyx | A. celestae |
| A derived sauropodomorph | ||
Antetonitrus | A. ingenipes |
| A derived sauropodomorph or basal sauropod | ||
Arcusaurus | A. pereirabdalorum |
|
| A basal sauropodomorph, known from juveniles | |
Blikanasaurus | B. cromptoni |
|
| A derived sauropodomorph or basal sauropod | |
Eucnemesaurus | E. fortis |
| A possible riojasaurid | ||
E. entaxonis | |||||
Euskelosaurus | E. browni |
| A plateosaurid, potentially dubious | ||
Gryponyx | G. africanus |
| A massospondylid, potentially dubious | ||
Ignavusaurus | I. rachelis |
| A massospondylid, known from a juvenile, potential synonym of Massospondylus | ||
Kholumolumo | K. ellenbergerorum |
| A basal sauropodiform | ||
Ledumahadi | L. mafube | A derived sauropodomorph or basal sauropod, largest in the formation | |||
Massospondylus | M. carinatus |
| A massospondylid, most common fossil found | ||
M. kaalae |
| A massospondylid, differs from M. carinatus in cranial features | |||
Melanorosaurus | M. readi |
|
| A derived sauropodomorph | |
Meroktenos | M. thabanensis |
|
| A derived sauropodomorph, formerly a species of Melanorosaurus | |
Plateosauravus | P. cullingworthi |
| A basal sauropodomorph, formerly specimens of Euskelosaurus | ||
Pulanesaura | P. eocollum |
| A derived sauropodomorph or basal sauropod | ||
Sefapanosaurus | S. zastronensis |
| A derived sauropodomorph | ||
Theropods of the Elliot Formation | |||||
---|---|---|---|---|---|
Genus | Species | Location | Stratigraphy | Notes | Images |
Dracovenator | D. regenti |
|
| A dilophosaurid | |
Megapnosaurus | M. rhodesiensis |
|
| A coelophysid | |
Crocodylomorphs of the Elliot Formation | ||||||
---|---|---|---|---|---|---|
Genus | Species | Location | Stratigraphy | Notes | Images | |
Basutodon | B. ferox |
| A dubious suchian | |||
Litargosuchus | L. leptorhynchus |
|
| A basal crocodylomorph | ||
Orthosuchus | O. stormbergi |
| A possible protosuchid | |||
Rauisuchian |
| A indeterminate large "Rauisuchian" | ||||
Sphenosuchus | S. acutus |
| A large basal crocodylomorph | |||
Synapsids of the Elliot Formation | ||||||
---|---|---|---|---|---|---|
Genus | Species | Location | Stratigraphy | Notes | Images | |
Elliotherium | E. kersteni |
| A tritheledontid cynodont | |||
Megazostrodon | M. rudnerae |
| A megazostrodontid cynodont | |||
Pentasaurus | P. goggai |
| A stahleckeriid dicynodont | |||
Scalenodontoides | S. macrodontes |
| A very large traversodontid cynodont | |||
Lesothosaurus is a monospecific genus of ornithischian dinosaur that lived during the Early Jurassic in what is now South Africa and Lesotho. It was named by paleontologist Peter Galton in 1978, the name meaning "lizard from Lesotho". The genus has only one valid species, Lesothosaurus diagnosticus. Lesothosaurus is one of the most completely-known early ornithischians, based on numerous skull and postcranial fossils from the Upper Elliot Formation. It had a simpler tooth and jaw anatomy than later ornithischians, and may have been omnivorous in some parts of the year.
Melanorosaurus is a genus of basal sauropodomorph dinosaur that lived during the Late Triassic period. An omnivore from South Africa, it had a large body and sturdy limbs, suggesting it moved quadrupedally. Its limb bones were massive and heavy like the limb bones of true sauropods.
Abrictosaurus is a genus of heterodontosaurid dinosaur that lived during the Early Jurassic in what is now in parts of southern Africa such as Lesotho and South Africa. It was a bipedal herbivore or omnivore and was one of the most basal heterodontosaurids. It was approximately 1.2 metres (3.9 ft) long and weighed between 0.68 and 3 kilograms.
Vulcanodon is an extinct genus of sauropod dinosaur from the Early Jurassic Uppermost Forest Sandstone of southern Africa. The only known species is V. karibaensis. Discovered in 1969 in Zimbabwe, it was regarded as the earliest-known sauropod for decades, and is still one of the most primitive sauropods that has been discovered. As a quadrupedal, ground-dwelling herbivore, Vulcanodon already showed the typical sauropod body plan with column-like legs and a long neck and tail. It was smaller than most other sauropods, measuring approximately eleven metres (36 ft) in length. Vulcanodon is known from a fragmentary skeleton including much of the pelvic girdle, hindlimbs, forearms, and tail, but lacking the trunk and neck vertebrae as well as the skull.
Massospondylus was a genus of sauropodomorph dinosaur from the Early Jurassic. It was described by Sir Richard Owen in 1854 from remains discovered in South Africa, and is thus one of the first dinosaurs to have been named. Fossils have since been found at other locations in South Africa, Lesotho, and Zimbabwe. Material from Arizona's Kayenta Formation, India, and Argentina has been assigned to the genus at various times, but the Arizonan and Argentinian material are now assigned to other genera.
Antetonitrus is a genus of sauropodiform dinosaur found in the Early Jurassic Elliot Formation of South Africa. The only species is Antetonitrus ingenipes. Sometimes considered a basal sauropod, it is crucial for the understanding of the origin and early evolution of this group. It was a quadrupedal herbivore, like its later relatives, but shows primitive adaptations to use the forelimbs for grasping, instead of purely for weight support.
Blikanasaurus is a genus of sauropodomorph dinosaur from the late Triassic of South Africa. The generic name Blikanasaurus is derived from Greek, meaning "lizard from Blikana". The species name cromptoni is taken from the surname of A.W. "Fuzz" Crompton, an American paleontologist who led numerous field expeditions in Elliot Formation outcrop localities in South Africa. Blikanasaurus is only known from partial hindlimb bones that were recovered from the lower Elliot Formation (LEF) in the Eastern Cape.
Gryponyx is an extinct genus of massopod sauropodomorph known from southern Free State, central South Africa.
The Clarens Formation is a geological formation found in several localities in Lesotho and in the Free State, KwaZulu-Natal, and Eastern Cape provinces in South Africa. It is the uppermost of the three formations found in the Stormberg Group of the greater Karoo Supergroup rocks and represents the final phase of preserved sedimentation of the Karoo Basin.
Massospondylidae is a family of early massopod dinosaurs that existed in Asia, Africa, North America, South America and Antarctica during the Late Triassic to the Early Jurassic periods. Several dinosaurs have been classified as massospondylids over the years. The largest cladistic analysis of early sauropodomorphs, which was presented by Apaldetti and colleagues in November 2011, found Adeopapposaurus, Coloradisaurus, Glacialisaurus, Massospondylus, Leyesaurus and Lufengosaurus to be massospondylids. This result supports many previous analyses that tested fewer taxa. However, this analysis found the two recently described North American massopods, Sarahsaurus and Seitaad, and the South African Ignavusaurus to nest outside Massospondylidae, as opposed to some provisional proposals. Earlier in 2011, Pradhania, a sauropodomorph from India, was tested for the first time in a large cladistic analysis and was found to be a relatively basal massospondylid. Mussaurus and Xixiposaurus may also be included within Massospondylidae.
Notochampsa is an extinct genus of protosuchian crocodyliform. Fossils have been found from the lower Clarens Formation of the Karoo Supergroup in South Africa, dating back to the Pliensbachian stage of the Early Jurassic. Notochampsa comes from a period of relative fossil scarcity, and is the youngest known occurrence of a crocodylomorph from the Karoo Basin of South Africa.
The Molteno Formation is a geological formation found in several localities in Lesotho and South Africa. It lies mainly south of Maseru, near Burgersdorp, Aliwal North, Dordrecht, Molteno, and Elliot. It extends as far north as Matatiele in the Eastern Cape. The formation's localities lie along the Drakensberg Mountains in Kwazulu-Natal, and near Ladybrand in the Free State of South Africa. The Molteno Formation is the lowermost of the three formations in the Stormberg Group of the greater Karoo Supergroup. The Molteno Formation represents the initial phase of preserved sedimentation of the Stormberg Group.
The Pebbly Arkose Formation is a Late Triassic geologic formation found in southern Africa.
Ignavusaurus is a genus of basal sauropodomorph dinosaur that lived during the Early Jurassic in what is now Lesotho. Its fossils were found in the Upper Elliot Formation which is probably Hettangian in age. It was described on the basis of a partial, well preserved articulated skeleton. The type species, I. rachelis, was described in 2010 by Spanish palaeontologist F. Knoll.
The Stormberg Group is one of the four geological groups that comprises the Karoo Supergroup in South Africa. It is the uppermost geological group representing the final phase of preserved sedimentation of the Karoo Basin. The Stormberg Group rocks are considered to range between Lower Triassic (Olenekian) to Lower Jurassic (Pliensbachian) in age. These estimates are based on means of geological dating including stratigraphic position, lithostratigraphic and biostratigraphic correlations, and palynological analyses.
Pegomastax is a genus of heterodontosaurid dinosaur that lived during the Early Jurassic of South Africa. The only known specimen was discovered in a 1966–1967 expedition in Transkei District of Cape Province, but was not described until 2012 when Paul Sereno named it as the new taxon Pegomastax africana. The genus name is derived from the Greek for "strong jaw", and the species name describes the provenance of Africa; it was originally spelled africanus, was corrected to africana to align with the gender of the genus name.
Pentasaurus is an extinct genus of dicynodont of the family Stahleckeriidae, closely related to the well known Placerias. It was found in the Lower Elliot Formation of South Africa, dated to the Norian of the Late Triassic period. The genus contains the type and only species, Pentasaurus goggai. Pentasaurus is named after the ichnogenus Pentasauropus, fossil footprints that were originally described from the lower Elliot Formation in 1970 decades before the body fossils of Pentasaurus itself were recognised. Pentasauropus footprints were likely made by dicynodonts, and in South Africa Pentasaurus itself was the likely trackmaker. The name reflects the fact that a large dicynodont was predicted to have existed in the lower Elliot Formation before any body fossils were recognised, and so Pentasaurus was named after its probable footprints. This is a reversal of the more typical occurrence where fossil footprints are named after their presumed trackmakers. The name of the species honours its collector Alfred Brown, nicknamed "Gogga", which means "bug" in Afrikaans.
Lessemsauridae is a clade of early sauropodiform dinosaurs that lived in the Triassic and Jurassic of Argentina, South Africa and possibly Lesotho. A phylogenetic analysis performed by Apaldetti and colleagues in 2018 recovered a new clade of sauropodiforms uniting Lessemsaurus, Antetonitrus, and Ingentia which they named Lessemsauridae. It is a node-based taxon, defined as all descendants of the most recent common ancestor of Lessemsaurus sauropoides and Antetonitrus ingenipes. Depending on the definition of Sauropoda, Lessemsauridae is either one of the most basal sauropod taxa, or a sister taxon of Sauropoda. An additional member of the clade was named later in 2018, Ledumahadi. A 2021 study by Pol and colleagues also assigned the genera Kholumolumo and Meroktenos to the group.
Ngwevu is a genus of massospondylid sauropodomorph dinosaur from the Lower Jurassic of South Africa. The genus contains one species, Ngwevu intloko.
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