Aoufous Formation | |
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Stratigraphic range: Early Cenomanian ~ | |
Type | Geological formation |
Unit of | Kem Kem Group |
Underlies | Ifezouane Formation |
Overlies | Akrabou Formation |
Thickness | 100–200 m (330–660 ft) |
Lithology | |
Primary | Sandstone, claystone, limestone |
Other | Marl, gypsum |
Location | |
Coordinates | 31°48′N5°54′W / 31.8°N 5.9°W |
Approximate paleocoordinates | 19°18′N5°18′W / 19.3°N 5.3°W |
Region | Errachidia Province |
Country | Morocco |
Extent | Anti-Atlas-Sahara craton |
Type section | |
Named for | Aoufous |
Named by | Dubar |
Year defined | 1948 |
The Aoufous Formation is a geological formation that contains some of the vertebrate assemblage of the Kem Kem Group, of Late Cretaceous date. [1] [2] Two other formations comprise the Kem Kem beds: the underlying Ifezouane Formation and the overlying Akrabou Formation.
The Aoufous Formation was first reported by Dubar (1948) as part of the “Sillon Preafricain”. Dubar described it from a lithological point of view as consisting mainly of clay-sandstones and green marls with gypsum. Dubar dated the sediments to the Albian / Cenomanian stages. Later, Sereno et al. (1996) reported an informal division of the Kem Kem Beds: a lower red sandstone unit ("gres infrecenomanien") and an upper marley unit ("marne versicolores a gypse"). Because of the absence of hiatuses between and within the three formations, the represented time scale is of around 8 million years, covering the time from the Early Cenomanian to the Middle Turonian. The Aoufous Formation is exposed from the Anti-Atlas and High Atlas mountain ranges up to the Sahara craton, in the southeastern part of Morocco. The formation is 100 to 200 metres (330 to 660 ft) thick. [3]
In the early Mesozoic Era, the main displacement of the African continent was from south to north, in the direction of Europe. The Atlantic Ocean was opening with high rates of expansion. This caused the uplift of the western part of Morocco, causing exposure of Precambrian and Paleozoic rocks, and prevented a continuous deposition of Mesozoic sediments in western Morocco. In the Jurassic, most of modern Morocco had already emerged. The first marine transgression is dated to the Early Barremian. During the Barremian-Aptian, two elongated marine gulfs extended northwards along the Middle-Atlas and from the western Essaouira Basin. In the Early Cretaceous, Northern Africa was covered with deltaic and brackish environments. These deposits comprise the Kem Kem Beds and thus the Aoufous Formation too.
The Aoufous Formation shows a similar fauna to that one found in the Bahariya Formation of Egypt. In both these formations, Carcharodontosaurus saharicus and Spinosaurus aegyptiacus are found. In addition, several species of crocodilians and fishes are shared. The Bahariya Formation is well dated to the Early Cenomanian. The rare microfossils found in the Aoufous Formation were not helpful in dating these sediments. For these reasons, the age of the Aoufous Formation is considered early Cenomanian.
The Aoufous Formation is characterized by three facies: variegated claystones, gypsum layers and dolomitic limestones. Claystones contain organic matter. Vertebrate remains (mostly fishes) are found in these claystones. No calcitic shells are found there, but apatitic microfossils are present. Quartz and marcasite (typical of a reducing environment) are quite frequent.
In carbonaceous facies, vertebrate fossils are present. The dolomitisation of these sediments destroyed any organic presence in them. Gastropods, thin-shelled and thick-shelled ostracods and some rare agglutinated foraminifers are present in this facies. Quartz is present with different morphologies, suggesting eolian (wind-based) and fluvial (river-based) transport.
In the gypsum layers, fossils are absent. These layers testify to long periods of dryness connected to evaporation of salty waters. The facies and the fossil remains suggest a paleoenvironment as a coastal lagoon or a paralic sebkha.
OT1 is a locality (10 kilometres (6.2 mi) away from Tafraout) characterized by lenses of claystone. Several fossil articulated fishes, gastropods and crustaceans specimens were recovered from this locality. The stratigraphic position of these lenses of claystone lies within the Aoufous Formation. Several features differentiate this facies from the others that are commonly encountered in the Aoufous Formation, and, for this reason, they are usually described apart.
The fauna of these lenses is characterized from three cladistians ( Serenoichthys kemkemensis and two other unnamed genera), an indeterminate actinopterygian, and the oldest known freshwater acanthomorph ( Spinocaudichthys oumtkoutensis ). The paleoenvironment of OT1 has been interpreted as a quiet lake, where the process of fossilization was quite rapid (soft tissues are generally preserved).
Because fossils from the formation are usually retrieved by local people who are untrained as geologists, it is difficult to know the exact provenance of many of them. For this reason, the provenance of a fossil from the Ifezouane and the Aoufous Formations is not generally specified; in any case the two formations seem to present the same fauna.
The most common vertebrate remains belong to the elasmobranch fish Onchopristis numidus . Another seven elasmobranchs are reported: Asteracanthus aegyptiacus , Distobatus nutiae , Tribodus sp., Lissodus sp., Haimirichia amonensis , Cretoxyrhinidae indet., and Marckgrafia lybica . Lungfish fossils are referred to Ceratodus humei and Neoceratodus africanus . Coelacanth remains are referred to Mawsonia lavocati and to the genus Axelrodichthys . Several taxa of Cladistia and two genera of seminiomorphs (an unnamed Lepidotes -like species and Oniichthys falipoui ) are recovered in the Kem Kem beds. Teleosteans are represented by Cladocyclus pankowskii , Palaeonotopterus greenwoodi , Erfoudichthys rosae and Concavotectum moroccensis . Amphibians are also present: Kababisha sp., the pipid frog Oumtkoutia anae and non-pipids frogs. Turtles are represented by several species: Dirqadim schaefferi , the podocnemidids Hamadachelys escuilliei , the bothremydids Galianemys whitei and G. emringeri, and the araripemydids Araripemys sp. Crocodilians are commonly found; four species are present: Elosuchus cherifiensis , a genus belonged to the Trematochampsidae, Araripesuchus rattoides and Laganosuchus maghrebensis .
In regards to dinosaurs, a rebbachisaurid ( Rebbachisaurus garasbae ) and some ornithischian footprints were recovered in the Kem Kem Beds; the most important presence belongs to theropods. Among theropods, two carcharodontosaurids ( Carcharodontosaurus saharicus and Sauroniops pachytholus ), one spinosaurid ( Spinosaurus aegyptiacus ), two ceratosaurs ( Deltadromeus agilis and an unnamed abelisaur) and an unnamed dromaeosaur characterize the assemblage.
Pterosaurs are also present, although their fossils are extremely rare and enigmatic: an azhdarchid, an ornithocheirid, a tapejarid and a pteranodontid are recognized.
Spinosaurus is a genus of spinosaurid dinosaur that lived in what now is North Africa during the Cenomanian stage of the Late Cretaceous period, about 100 to 94 million years ago. The genus was known first from Egyptian remains discovered in 1912 and described by German palaeontologist Ernst Stromer in 1915. The original remains were destroyed in World War II, but additional material came to light in the early 21st century. It is unclear whether one or two species are represented in the fossils reported in the scientific literature. The best known species is S. aegyptiacus from Egypt, although a potential second species, S. maroccanus, has been recovered from Morocco. The contemporary spinosaurid genus Sigilmassasaurus has also been synonymized by some authors with S. aegyptiacus, though other researchers propose it to be a distinct taxon. Another possible junior synonym is Oxalaia from the Alcântara Formation in Brazil.
Carcharodontosaurus is a genus of carnivorous theropod dinosaur that lived in North Africa from about 100 to 94 million years ago during the Cenomanian age of the Late Cretaceous. Two teeth of the genus, now lost, were first described from Algeria by French paleontologists Charles Depéret and Justin Savornin as Megalosaurus saharicus. A partial skeleton was collected by crews of German paleontologist Ernst Stromer during a 1914 expedition to Egypt. Stromer did not report the Egyptian find until 1931, in which he dubbed the novel genus Carcharodontosaurus, making the type species C. saharicus. Unfortunately, this skeleton was destroyed during the Second World War. In 1995 a nearly complete skull of C. saharicus, the first well-preserved specimen to be found in almost a century, was discovered in the Kem Kem Beds of Morocco; it was designated the neotype in 1996. Fossils unearthed from the Echkar Formation of northern Niger were described and named as another species, C. iguidensis, in 2007.
Spinosauridae is a clade or family of tetanuran theropod dinosaurs comprising ten to seventeen known genera. Spinosaurid fossils have been recovered worldwide, including Africa, Europe, South America and Asia. Their remains have generally been attributed to the Early to Mid Cretaceous.
Rugops is a monospecific genus of basal abelisaurid theropod dinosaur from Niger that lived during the Late Cretaceous period in what is now the Echkar Formation. The type and only species, Rugops primus, is known only from a partial skull. It was named and described in 2004 by Paul Sereno, Jeffery Wilson and Jack Conrad. Rugops has an estimated length of 4.4–5.3 metres (14–17 ft) and weight of 410 kilograms (900 lb). The top of its skull bears several pits which correlates with overlaying scale and the front of the snout would have had an armour-like dermis.
Bahariasaurus is an enigmatic genus of large theropod dinosaur. The genus is known to have included at least 1 species, Bahariasaurus ingens, which was found in North African rock layers dating to the Cenomanian and Turonian ages of the Late Cretaceous. The only fossils confidently assigned to Bahariasaurus were found in the Bahariya Formation of the Bahariya oasis in Egypt by Ernst Stromer but were destroyed during a World War II bombing raid with the same raid taking out the holotype of Spinosaurus and Aegyptosaurus among other animals found in the Bahariya Formation. While there have been more fossils assigned to the genus such as some from the Farak Formation of Niger, these remains are referred to with much less certainty. Bahariasaurus is, by most estimations, one of the largest theropods, approaching the height and length of other large bodied theropods such as Tyrannosaurus rex and the contemporaneous Carcharodontosaurus. The aforementioned estimations tend to put it at around 11–12.2 metres in length and 4-4.8 tonnes in overall weight.
Deltadromeus is a genus of theropod dinosaur from the Aoufous Formation of Morocco.
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.
Cristatusaurus is a genus of theropod dinosaur that lived during the Early Cretaceous Period of what is now Niger, 112 million years ago. It was a baryonychine member of the Spinosauridae, a group of large bipedal carnivores with well-built forelimbs and elongated, crocodile-like skulls. The type species Cristatusaurus lapparenti was named in 1998 by scientists Philippe Taquet and Dale Russell, on the basis of jaw bones and some vertebrae. Two claw fossils were also later assigned to Cristatusaurus. The animal's generic name, which means "crested reptile", alludes to a sagittal crest on top of its snout; while the specific name is in honor of the French paleontologist Albert-Félix de Lapparent. Cristatusaurus is known from the Albian to Aptian Elrhaz Formation, where it would have coexisted with sauropod and iguanodontian dinosaurs, other theropods, and various crocodylomorphs.
Sigilmassasaurus is a controversial genus of spinosaurid dinosaur that lived approximately 100 to 94 million years ago during the Late Cretaceous Period in what is now northern Africa. Named in 1996 by Canadian paleontologist Dale Russell, it contains a single species, Sigilmassasaurus brevicollis. The identity of the genus has been debated by scientists, with some considering its fossils to represent material from the closely related species Spinosaurus aegyptiacus, while others have classified it as a separate taxon, forming the clade Spinosaurini with Spinosaurus as its sister taxon.
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 Chenini Member is a geological member of the Ain el Guettar Formation in Tunisia, whose strata date back to the Late Aptian to Early Albian stages of the Cretaceous period. The lithology consists of coarse sandstones with occasional conglomerates and mudstones. Dinosaur remains are among the fossils that have been recovered from the formation.
The Kem Kem Group is a geological group in the Kem Kem region of eastern Morocco, whose strata date back to the Cenomanian stage of the Late Cretaceous. Its strata are subdivided into two geological formations, with the lower Ifezouane Formation and the upper Aoufous Formation used for the strata on the eastern side of the Atlas Mountains (Tinghir), with the Gara Sbaa Formation and Douira Formation used in the southern Tafilalt region. It is exposed on an escarpment along the Algeria–Morocco border.
Paranogmius is an extinct genus of prehistoric bony fish that lived during the Cenomanian. It is known from only 2 partial skulls and several dorsal vertebrae discovered in the Bahariya Formation that was destroyed during World War II. Since then, no more fossils have been discovered. It may have been up to 3 meters long.
Kemkemia is a genus of probable crocodyliforms living in the Cretaceous, described from a single fossil that was recovered in 1999 from Morocco by an Italian team searching for fossil invertebrates. The fossil of Kemkemia dates from the Cenomanian age.
Oxalaia is a genus of spinosaurid dinosaur that lived in what is now the Northeast Region of Brazil during the Cenomanian stage of the Late Cretaceous period, sometime between 100.5 and 93.9 million years ago. Its only known fossils were found in 1999 on Cajual Island in the rocks of the Alcântara Formation, which is known for its abundance of fragmentary, isolated fossil specimens. The remains of Oxalaia were described in 2011 by Brazilian palaeontologist Alexander Kellner and colleagues, who assigned the specimens to a new genus containing one species, Oxalaia quilombensis. The species name refers to the Brazilian quilombo settlements. Oxalaia quilombensis is the eighth officially named theropod species from Brazil and the largest carnivorous dinosaur discovered there. It is closely related to the African genus Spinosaurus, and/or may be a junior synonym of this taxon.
Onchopristis is an extinct genus of sclerorhynchoid from the Cretaceous of North Africa, Europe, and North America. Its name is derived from the Ancient Greek ónkos and prístis. It contains two valid species, O. numida and O. dunklei, though some researchers argue that both may be considered a single taxon with variation in morphology caused by a wide geographical range. Specimens of Onchopristis have been discovered in coastal and fluvial deposits dated from the Barremian to the Cenomanian age, making this genus one of the oldest and longest-lived sclerorhynchoid genera.
Sauroniops is a controversial genus of carnivorous basal carcharodontosaurid theropod dinosaur known from the Late Cretaceous Gara Sbaa Formation, and possibly also the Kem Kem Formation, both of Morocco. The type, and currently only, species is S. platytholus.
Concavotectum is an extinct genus of freshwater plethodid ray-finned fish that lived during the Cenomanian in Morocco and possibly Egypt. It was discovered and named in 2008 and is known from a single well preserved hand-sized skull and a few isolated vertebrae discovered in the Kem Kem Group. The type species, C. moroccensis, was named in 2008 and described in 2010.
Nizar Ibrahim is a German-Moroccan vertebrate paleontologist and comparative anatomist. He is currently a senior lecturer at the University of Portsmouth. Ibrahim has led several expeditions to Africa's Sahara and is notable for his research on fossil vertebrates from the Kem Kem Group, including pterosaurs, crocodyliforms, and dinosaurs. In recent years, research led by Ibrahim radically changed ideas about the morphology and life habits of one of the largest predatory dinosaurs, Spinosaurus aegyptiacus. Ibrahim also has interests in bioinformatics and contributed to the NSF-funded Phenoscape project. He regularly engages with the public and is a speaker with the National Geographic Speakers Bureau.
Afrocascudo is a controversial genus of extinct neopterygian fish, either an ancient loricariid catfish or a juvenile obaichthyid lepisosteiform of the genus Obaichthys. It is known from the Late Cretaceous Douira Formation of Morocco. The genus contains a single species, A. saharaensis, known from a partial articulated specimen.
This article includes a list of general references, but it lacks sufficient corresponding inline citations .(November 2013) |