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Découverte d'un nouveau gisement de stégocéphales d'une conservation exceptionnelle dans le Trias d'In Amenas (Bassin d'illizi, Algérie)

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In the In Amenas area, in the North part of the Basin of Illizi, an exceptional new fossil Amphibia deposit as regards richness and conservation has been discovered. It is localized at the base (Formation I of 10m thickness) of the Triassic argilo-sandy series of Zarzaïtine of which the reference cross section is plotted in the place called «La Reculée» in an interval corresponding to a sebkha filling (Lagerstätte). The paleontological site extended over10x10m2 delivered well preserved crania,piled up the ones on the others, as well as some associated post-cranial elements, of which ribs and vertebras. It testifies to a mass mortality. The preliminary identification of the specimen described in this paper would let believe that it is about a new species of paracyclotosaur, capitosaur group (temnospondyl Amphibia). This discovery allows: i) to confirm the Lower- Middle Triassic age of the base of the «série de Zarzaïtine»; ii) to show a local paleoclimate characterized by alternation from dry to humid periods and ending into dry, - to propose that this site must be protected. Another paper will complete this one and will be in relation, particularly, with the systematic, phylogenetic and paleobiological study of the collected stegocephales.
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... More recently, regular geological and palaeontological fieldwork was conducted in the Illizi Basin by the "Laboratoire de Géodynamique des Bassins Sédimentaires et des Orogènes" of the University of Science and Technology Houari Boumedienne, the "Agence du Service Géologique de l'Algérie", the Société Nationale pour la Recherche, la Production, le Transport, la Transformation et la Commercialisation des Hydrocarbures (SONATRACH), and within the framework of an international collaboration program with the "Centre de Recherches en Paléobiodiversité et Paléoenvironnements" (CNRS, Paris). Palaeontological prospecting, conducted in 2008 and2009 in the area of "La Reculée", led to the discovery (and systematic excavations) of a new Lagerstätte preserving numerous and exceptionally well preserved temnospondyl specimens Dahoumane, 2011;Nedjari et al., 2010). We refer to Nedjari et al. (2010) and for the complete description of the site including stratigraphy, sedimentology and taphonomy. ...
... Palaeontological prospecting, conducted in 2008 and2009 in the area of "La Reculée", led to the discovery (and systematic excavations) of a new Lagerstätte preserving numerous and exceptionally well preserved temnospondyl specimens Dahoumane, 2011;Nedjari et al., 2010). We refer to Nedjari et al. (2010) and for the complete description of the site including stratigraphy, sedimentology and taphonomy. ...
... Type Locality and Horizon-"La Reculée" area ( Fig. 1), Zarzaïtine district, In Amenas region, southern Algeria; base of the "Formation 0" sensu Aït Ouali et al., 2011 (= "Grès Inférieurs" or Lower Sandstone Unit sensu Busson, 1971;Groult, 1970), lower section of the Zarzaïtine Series of the Illizi Basin, Lower-Middle Triassic according to Nedjari et al. (2010) and . ...
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We describe a new species of mastodonsauroid temnospondyl from Algeria, Stanocephalosaurus amenasensis nov. sp., on the basis of two exquisite skulls from a Lagerstätte found in the lowermost formation of the Zarzaïtine Series, Illizi Basin, in the area of “La Reculée”, In Amenas region, Algeria. The new species is characterized by subtriangular nostrils with concave lateral borders; small orbits; postfrontals posteriorly very wide; very elongate parietals; smoothly concave posterior margin of the skull; ovoid anterior palatal vacuities; very posteriorly pointed choanae; oval interpterygoid fenestrae; and a short anterior extension of the cultriform process of the parasphenoid. S. amenasensis is different than the Algerian taxa previously erected by Lehman (1971)–“Parotosaurus lapparenti” and “Wellesaurus bussoni”–which we consider nomina dubia. It enlarges the distribution of the genus in northern Gondwana and supports the Early-Middle Triassic age of the lowermost formation of the Zarzaïtine Series. It also suggests that the local palaeoclimate was very seasonal and these aquatic amphibians died massively in a dewatering sebkha.
... An exceptionally well-preserved skull of the capitosaurian Stanocephalosaurus, recently found in 3-D in the Triassic of Algeria (Nedjari et al., 2010), has been used for cranial exploration: specimen ZAR05 (collections of the University of Alger) has been analysed by X-ray micro-CT scan AST-RX at MNHN, Paris. Its complete endocranial description is given here based on the resulting highly detailed 3-D computer-based reconstruction and leads to new morphological observations and interpretations. ...
... The studied taxon is the capitosaurian temnospondyl Stanocephalosaurus amenasensis (Dahoumane et al., 2016) from the Lower-Middle Triassic of the Zarzaïtine Series, Illizi Basin, Southeastern Algeria. The analysis is based on an exquisite skull (specimen ZAR05 of the collections of the Faculté des Sciences de la Terre, de Géographie et de l'Aménagement du Territoire, Alger, Algeria; Fig. 1) collected in a Lagerstätte (Nedjari et al., 2010;Aït Ouali et al., 2011) and preserved in 3-D. This skull is about 23.5 cm in length (only the tip of the snout is missing) and its dorsal surface ornamented, as in adult temnospondyls (e.g. ...
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