Douiret Formation | |
---|---|
Stratigraphic range: Hauterivian-Aptian ~ | |
Type | Geological formation |
Unit of | Merbah el Asfer Group |
Underlies | Chenini Formation |
Overlies | Boulouha Formation |
Lithology | |
Primary | Sandstone, claystone |
Location | |
Coordinates | 32°42′N10°12′E / 32.7°N 10.2°E |
Approximate paleocoordinates | 17°48′N11°54′E / 17.8°N 11.9°E |
Region | Tatouine |
Country | Tunisia |
The Douiret Formation is a geologic formation in Tunisia, near the Berber village of Douiret. It is part of the larger Continental Intercalaire Formation, which stretches from Algeria and Niger in the west to Egypt and Sudan in the east. [1] [2] The Douiret Formation is located in the Tataouine basin in southern Tunisia, stretching into Algeria and Libya, and is part of the Merbah el Asfer Group of rock formations. [1] [2] The Douiret is 80 metres thick and consists of a 30-metre layer of sand beneath a 50-metre layer of clay. [2] [3]
A few fossil-bearing beds have been discovered in the sand layer. [1] [2] The fossils range from the Aptian to Albian period [2] and include freshwater and marginal marine sharks, skates, fish, turtles, crocodilians, pterosaurs, bivalves, pollens and plants, including trees. [2] The fish are the most abundant type of fossil found. [1] The orientation of the fossils suggests the earlier ones were deposited by a westward flowing paleocurrent while the later ones were laid down in waves. [2] Dinosaur remains consisting of the remains of a single indeterminate iguanodontid ornithopod are also among the fossils that have been recovered from the formation, [2] although none have yet been referred to a specific genus. [4]
The green clay layer contains plant remains (ferns and conifers), but no vertebrate or flowering plant remains. [2]
The Douiret formation dates from the Early Cretaceous period, more than 100 million years ago. [1] Scientists have dated the sandy layer to the Hauterivian, Barremian or Aptian periods (132 to 113 million years ago) and the clay layer to the Barremian or Aptian periods (130 to 113 million years ago). [1] [2] [3]
Based on both the geology of the formation and the fossils found, scientists agree that the sandy part of the Douiret Formation was a lush coast or more likely river delta on the shore of the Tethys Sea, [1] [3] but by the time of the clay layer, tectonic subsidence and the northward migration of the Tethys Sea had turned the area into a huge freshwater lagoon that periodically dried into a salt flat, hostile to vegetation. [2] [1]
Sarcosuchus is an extinct genus of crocodyliform and distant relative of living crocodilians that lived during the Early Cretaceous, from the late Hauterivian to the early Albian, 133 to 112 million years ago of what is now Africa and South America. The genus name comes from the Greek σάρξ (sarx) meaning flesh and σοῦχος (souchus) meaning crocodile. It was one of the largest crocodile-like reptiles, with the largest specimen of S. imperator reaching approximately 9–9.5 metres (29.5–31.2 ft) long and weighing up to 3.45–4.3 metric tons. It is known from two species, S. imperator from the early Albian Elrhaz Formation of Niger and S. hartti from the Late Hauterivian of northeastern Brazil, other material is known from Morocco and Tunisia and possibly Libya and Mali.
Weald Clay or the Weald Clay Formation is a Lower Cretaceous sedimentary rock unit underlying areas of South East England, between the North and South Downs, in an area called the Weald Basin. It is the uppermost unit of the Wealden Group of rocks within the Weald Basin, and the upper portion of the unit is equivalent in age to the exposed portion of the Wessex Formation on the Isle of Wight. It predominantly consists of thinly bedded mudstone. The un-weathered form is blue/grey, and the yellow/orange is the weathered form, it is used in brickmaking.
Rebbachisaurus is a genus of sauropod dinosaur of the superfamily Diplodocoidea, that lived during the Late Cretaceous period in Africa and possibly also South America about 99-97 million years ago. Remains attributed to Rebbachisaurus have been found in Morocco, Niger, Algeria, Tunisia and possibly also Argentina, although only the Moroccan remains can be referred to the genus without doubt. The discovery of Rayososaurus, a South American sauropod nearly identical to Rebbachisaurus which may have actually have been the same animal as Rebbachisaurus, supports the theory that there was still a land connection between Africa and South America during the Early Cretaceous, long after it was commonly thought the two continents had separated.
Rhabdodon is a genus of ornithopod dinosaur that lived in Europe approximately 70-66 million years ago in the Late Cretaceous. It is similar in build to a very robust "hypsilophodont", though all modern phylogenetic analyses find this to be an unnatural grouping, and Rhabdodon to be a basal member of Iguanodontia. It was large amongst its relatives, measuring 4 m (13 ft) long and weighing 250 kg (550 lb), with some specimens possibly reaching up to 6 m (20 ft) long.
Tenontosaurus is a genus of medium- to large-sized ornithopod dinosaur. It was a relatively medium sized ornithopod, reaching 6 to 7 meters in length and 600 to 1,000 kilograms in body mass. It had an unusually long, broad tail, which like its back was stiffened with a network of bony tendons.
Siamosaurus is a genus of spinosaurid dinosaur that lived in what is now known as China and Thailand during the Early Cretaceous period and is the first reported spinosaurid from Asia. It is confidently known only from tooth fossils; the first were found in the Sao Khua Formation, with more teeth later recovered from the younger Khok Kruat Formation. The only species Siamosaurus suteethorni, whose name honours Thai palaeontologist Varavudh Suteethorn, was formally described in 1986. In 2009, four teeth from China previously attributed to a pliosaur—under the species "Sinopliosaurus" fusuiensis—were identified as those of a spinosaurid, possibly Siamosaurus. It is yet to be determined if two partial spinosaurid skeletons from Thailand and an isolated tooth from Japan also belong to Siamosaurus.
The Wealden Group, occasionally also referred to as the Wealden Supergroup, is a group in the lithostratigraphy of southern England. The Wealden group consists of paralic to continental (freshwater) facies sedimentary rocks of Berriasian to Aptian age and thus forms part of the English Lower Cretaceous. It is composed of alternating sands and clays. The sandy units were deposited in a flood plain of braided rivers, the clays mostly in a lagoonal coastal plain.
Suchosaurus is a spinosaurid dinosaur from Cretaceous England and Portugal, originally believed to be a genus of crocodile. The type material, consisting of teeth, was used by British palaeontologist Richard Owen to name the species S. cultridens in 1841. Later in 1897, French palaeontologist Henri-Émile Sauvage named a second species, S. girardi, based on two fragments from the mandible and one tooth discovered in Portugal. Suchosaurus is possibly a senior synonym of the contemporary spinosaurid Baryonyx, but is usually considered a dubious name due to the paucity of its remains, and is considered an indeterminate baryonychine. In the Wadhurst Clay Formation of what is now southern England, Suchosaurus lived alongside other dinosaurs, as well as plesiosaurs, mammals, and crocodyliforms.
The Cedar Mountain Formation is the name given to a distinctive sedimentary geologic formation in eastern Utah, spanning most of the early and mid-Cretaceous. The formation was named for Cedar Mountain in northern Emery County, Utah, where William Lee Stokes first studied the exposures in 1944.
The Antlers Formation is a stratum which ranges from Arkansas through southern Oklahoma into northeastern Texas. The stratum is 150 m (490 ft) thick consisting of silty to sandy mudstone and fine to coarse grained sandstone that is poorly to moderately sorted. The stratum is cemented with clay and calcium carbonate. In places the sandstone may be conglomeratic or ferruginous.
The Arundel Formation, also known as the Arundel Clay, is a clay-rich sedimentary rock formation, within the Potomac Group, found in Maryland of the United States of America. It is of Aptian age. This rock unit had been economically important as a source of iron ore, but is now more notable for its dinosaur fossils. It consists of clay lenses within depressions in the upper part of the Patuxent Formation that may represent oxbow swamp facies. It is named for Anne Arundel County, Maryland.
The Wessex Formation is a fossil-rich English geological formation that dates from the Berriasian to Barremian stages of the Early Cretaceous. It forms part of the Wealden Group and underlies the younger Vectis Formation and overlies the Durlston Formation. The dominant lithology of this unit is mudstone with some interbedded sandstones. It is part of the strata of the Wessex Basin, exposed in both the Isle of Purbeck and the Isle of Wight. While the Purbeck sections are largely barren of vertebrate remains, the Isle of Wight sections are well known for producing the richest and most diverse fauna in Early Cretaceous Europe.
The Vectis Formation is a geological formation on the Isle of Wight and Swanage, England whose strata were formed in the lowermost Aptian, approximately 125 million years ago. The environment of deposition was that of a freshwater coastal lagoon with occasional marine influence after the early Aptian marine transgression, transitioning from the floodplain environment of the underlying Wessex Formation. The primary lithology is of laminated grey mudstones. The Vectis Formation is composed of three geological members: the Shepherds Chine member, the Barnes High Sandstone member, and the Cowleaze Chine member. It is overlain by the fully marine Atherfield Clay Formation, part of the Lower Greensand Group. Dinosaur remains are among the fossils that have been recovered from the formation.
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The Continental intercalaire, sometimes referred to as the Continental intercalaire Formation, is a term applied to Cretaceous strata in Northern Africa. It is the largest single stratum found in Africa to date, being between 30 and 800 metres thick in some places. Fossils, including dinosaurs, have been recovered from this formation. The Continental intercalaire stretches from Algeria, Tunisia and Niger in the west to Egypt and Sudan in the east.
The Kirkwood Formation is a geological formation found in the Eastern and Western Cape provinces in South Africa. It is one of the four formations found within the Uitenhage Group of the Algoa Basin – its type locality – and in the neighbouring Gamtoos Basin. Outcrops of the Kirkwood are also found along the Worcester-Pletmos, Herbertsdale-Riversdale, Heidelberg-Mossel Bay, and Oudtshoorn-Gamtoos basin lines. At these basins the Kirkwood Formation underlies the Buffelskloof Formation and not the Sundays River Formation.
The Okurodani Formation is an Early Cretaceous geologic formation in central Honshu, Japan. Part of the Tetori Group, it primarily consists of freshwater continental sediments deposited in a floodplain environment, with occasional volcanic tuffite horizons. It has an uncertain age, probably dating between the Hauterivian and Aptian. An indeterminate iguanodontian dinosaur tooth has been recovered from the formation. Many other fossil vertebrates are known from the KO2 locality
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The Aoufous Formation is a geological formation that contains some of the vertebrate assemblage of the Kem Kem Group, of Late Cretaceous date. Two other formations comprise the Kem Kem beds: the underlying Ifezouane Formation and the overlying Akrabou Formation.
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