Signification paléoécologique et paléogéographique des bivalves du Carbonifère inférieur du bassin d’Ancenis (Massif armoricain)

Palaeoecological and palaeogeographical inferences from Early Carboniferous bivalves of the Ancenis Basin (Variscan belt, France). In the basal part of the Ancenis Formation, of Dinantian age, greenish to purple mudstones display a few bivalves, assigned to the genera Lithophaga, Modiolus, and Naiadites. Because Naiadites is considered to be a non-marine bivalve, and is only previously reported in Scotland in Dinantian rocks, a brackish environment can be assumed for the Ancenis Basin during the Early Carboniferous. To cite this article: M. Ballèvre, H. Lardeux, C. R. Palevol 4 (2005).     

Hyostragulum simplex n. sp. (Incertae sedis) du dévonien du massif armoricain intérêt paléobiogéographique et systématique

In the western part of the “Synclinorium median armoricain (Rade de Brest), the presence of Hyostragulum simplex n. sp. in the lower part of the Troaon formation (Upper Emsian) is a supplementary element of hercynian fauna in Brittany during lower devonian time.For the new species, characterised by the lack of a septum on the base of the corallite, a fibrous microstructure, perhaps trabecular, is shown. The systematic position of the genus is discussed but ends up with a suggestion to let it remain incertae sedis..     

Loreleiella nov. gen., nouvel éodévonariidé(Chonetacea,Brachiopoda) du Dévonien

The detailed morphological analysis of the dorsal interior of Chonetes arcuatus Hall, 1857, typespecies of the genus Eodevonaria (North American Lower Devonian), compared with those of the European species classically assigned to this genus, allows the erection of a new genus for the European eodevonariids. The phylogenetic relations of Loreleiella nov. gen. and its paleobiogeographic implication are discussed.     

La Formation du Faou (Dévonien inférieur du finistère):Nouvelles observations biostratigraphiques et mise en évidence d'une écozone

enDetailed biostratigraphic analysis of a section in the Faou Formation (Lower Devonian, western Armorican Massif) provides new data about the vertical distribution of benthic faunas in this lithostratigraphic unit. A new interpretation of the Siegenian-Emsian boundary is proposed and a Leptaenopyxis kerfornei Ecozone is recognized. The repetition of this ecozone in the succession, with the presence of brachiopods in life position, shows that the hydrodynamic flow, the nature and the volume of the deposits were irregular during the sedimentation of the Faou Formation.     

Suoidea du Miocène inférieur de Laugnac (Lot-et-Garonne, France)

The fossil vertebrate locality of Laugnac is the type locality of the Neogene mammalian zone MN2b. It has yielded many remains of Suoidea belonging to two different genera.Xenohyus venitor is characterized by its large size and especially its large central upper incisors, I1/ and I2/. It is quite difficult to know its phyletic relationships because the material is not abundant.Hyotherium cf.meisneri is more abundant with a quite good skull, pieces of skull, jaws and isolated teeth. It belongs to a peculiar lineage different from that ofH. major from Saint Gérand-le-Puy, France. It has some similarities withAureliachoerus aurelianensis from later geological levels (MN3-MN5).     

Nouvelles espèces d’Ancyrocrinus et d’Ammonicrinus,crinoïdes à pédoncule spécialisé du Dévonien armoricain (Brest,France)

New species of Ancyrocrinus and Ammonicrinus, crinoids, crinoids with specialized stem from the Armorican Devonian (Brest, France). The discovery of the oldest tetrameral grapnels of Ancyrocrinus, A. crozonensis n. sp., in the Lower Eifelian modifies considerably the previous evolutionary scheme and sets the problem of the transition from tetrameral to pentameral symmetry in the ancyrocrinid holdfasts. The presence of a new species of Ammonicrinus, A. kerdreoletensis n. sp., in the Upper Emsian suggests a North-Gondwanan origin of the genus. Its highly specialized structure of the stem, characteristic of the genus, was developed earlier than previously recognized. To cite this article: J. Le Menn, P.A. Jaouen, C. R. Palevol 2 (2003).     

Apport des ostracodes à l’interprétation séquentielle du Crétacé inférieur (Berriasien–Valanginien) du bassin d’Essaouira–Agadir (Maroc)

Contribution of the ostracods to the sequential interpretation of the Lower Cretaceous (Berriasian–Valanginian) of the Essaouira–Agadir Basin (Morocco). The analysis of the ostracod fauna from the Berriasian–Valanginian of the Essaouira–Agadir Basin (Morocco) allows us to make a narrow relationship between the sequential evolution (established on sedimentary, biostratigraphical and geochemical data) and the evolution of statistical parameters of ostracods. So, the number of individuals and the number of species present comparable fluctuations and follow perfectly the sequential evolution; classes of dominant and fortuitous frequency are the most meaningful, the specific renewal rate shows extremes values at the limits of sequences and at the basis of transgressive systems tracts. To cite this article: A. Rossi et al., C. R. Palevol 2 (2003) 133–141.     

Les faunes d'ammonites du Carixien inférieur et moyen du gisement des Cottards (Cher)

The study of the traditional Cottard layer forthe first time allows the exact succession of lower and middle Carixian ammonites to be established.The most striking fact is the evolution of the Tropidoceras-Acanthopleuroceras lineage, a regular modification of the ribbing density and L¹ structure, an iterative variation of section and tuberculization.Precisions are given on Polymorphites and Beaniceras and three new species are described: Polymorphites evolutus, Beaniceras cottardiense, Acanthopleuroceras alisiense.     

Biostratigraphie des Miospores et des Chitinozoaires du Silurien supérieur et du Dévonien dans le bassin d'Illizi (S.E. du Sahara algérien)

Core samples from the Illizi basin yielded well preservedmiospores and Chitinozoa. The detailed study of the range of these microfossils allows accurate age assignment for upper Silurian and Devonian subsurface strata of the southeastern part of the algerian Sahara. On the other hand, these biostratigraphical data demonstrate the occurrence of important stratigraphical gaps related to recurrent emersions.     

Deux Lycophytesavec structures conservées du dÉvonien supérieur D'Ukraine (U.R.S.S.)

A revision of fossil plants, with preserved structures, collected in the Upper Devonian of the Donetz Basin (Ukrainia) allows us to describe 2 Lycophyta. One of them is a new species: Colpodexylon (?) schopfii nov. sp.     

Une oasis aquatique à faune relique dans la Plaine du Danube inférieur

Résumé Etude d'un complexe de sources, situé dans la Plaine du Danube Inférieur (= Plaine Roumaine ou Plains de Valachie), à 100 m d'alt. environ. La station se caractérise par un complexe de facteurs uniques dans ce coin de (Europe: abondance de l'eau phréatique froide sortant à jour sur une surface restreinte, protection efficace grâce à une saulaie compacte, variété des substrats et abondance des sources trophiques. Ces éléments rendent possible l'existence d'une faune relique, comprenant rotifères, tardigrades, coléoptères, trichoptères, hydracariens, etc., espèces ayant ici leur seule station de la Plaine Roumaine. Les espèces qu'on signale dans le travail sont soit formes de montagne, soit à aréal septentrional ou septentrional-occidental, soit, enfin, caractéristiques pour les tourbières d'altitude, souvent même pour les tourbières acides à Sphagnum. On considère la faune du complexe de Corbii Ciungi comme un rests remarquable de la faune aquatique ayant peuplé la Plaine Roumaine antérieurement à la mise en friche sauvage des forêts et à l'extension impétueuse de l'agriculture, phénomènes ayant radicalement transformé ce territoire.     

Chronologie des sites du Pléistocène inférieur et moyen du nord de l’Afrique

North Africa, and in particular the Maghreb, is a key region for African prehistory in that it contains sites whose chronology covers the entire Pleistocene period from 2.5 Ma to the Holocene. In terms of culture, it fits into the general pattern of the Stone Age, but it has particularities that make it a region apart with its own cultures. Due to its climate and geographical position, between the desert regions of the south and the Mediterranean Sea to the north, it has offered mankind a diversity of landscapes and environments that are quite unique and favorable to the development of human evolution. Finally, this region gives access to Europe through several maritime passages (Gibraltar, Sicily), which were probably used during the Pleistocene, thus reinforcing the interest in studying this northern part of Africa. The recent development of numerous dating methods has made it possible to reinforce and consolidate the chronostratigraphic framework, which for many years had been based solely on radiocarbon dating. These methods have sometimes even contributed to the confirmation of ‘new’ ideas that have dusted off the existing framework of prehistory. This article presents a chronology of the main ancient sites of the Maghreb dated by different methods whose ages compared to the results obtained by other disciplines participate and contribute to a better understanding of the environmental and cultural framework of prehistoric Man.     

Les Anoures (Amphibiens) du pléistocène inférieur (« Villafranchien å) du Jebel Irhoud (carrir̀e « Ocre å), Maroc

Anurans (Amphibians) from the Late Pleistocene (“Villafranchian”) of Jebel Irhoud (“Ocre” quarry), Morocco. The Villafranchian anurans of Jebel Irhoud (“Ocre” quarry) Morocco, belong to the Discoglossidae (Baleaphryne), Bufonidae (Bufo cf. B. viridis, Bufo cf. B. regularis) and Ranidae (Rana sp.). The presence of Pelodytidae (Pelodytes) in this site is possible but not ascertained. The genus Baleaphryne is reported for the first time in Africa. Likewise, Pelodytes, if this identification proves correct, would be the first one ever found in Africa.     

Découverte des sites du Paléolithique inférieur au Nord de l’Arménie

For a long time, the scientific community assumed that the Acheulean culture was expressed on the territory of the Armenian Plateau as well as in the neighboring regions of the Caucasus only by its late phase; therefore, it appeared in the second half of the Middle Pleistocene. In recent years, the Armenian-Russian mission has discovered and studied much older Acheulean industries sites, located in northern Armenia (the Lori intermountain Depression). These industries, represented by archaic type tools (large hand axes, picks, choppers, chisel-like tools, scrapers, points, etc.), are discovered in three deposits of origin of proluvial genesis. In the Karakhach site, this type of industry is deposited in the lower levels of volcanic tuff and below; the U/Pb study of this level of tuff proposes a series of dates, assigned to the time interval between 1.944 + 0.046 and 1.75 + 0.02 Ma. The paleomagnetic study demonstrated the inverse polarity on the tuff and the normal polarity of the underlying deposits; in correlation with other dating, this fact allows to attribute the Acheulean layers of the site of Karakhatch to the Lower Pleistocene, in particular to the Oldoway episode and to the Upper Matuyama time period. The estimated age and the techno-morphological characteristics of the tools indicate the Lower Acheulean period. The dating of the Muradovo site does not seem possible, however its very old industries and the archaeological layers, where they were discovered, find equivalents in the layered layer, surmounted by tuffs, of the Karakhatch site. The Kutran I site presented a paleosol sequence with similar Acheulean tools (hand axes, picks, choppers, etc.). Its oldest layer is older than 1.5 Ma, the upper layer is attributed to the early Middle Pleistocene; this fact means that it is possible to speak of the Lower Acheulean and of its transition to the Middle Acheulean period. The specific character and the age of the Lower Acheulean of Armenia admit that it could have formed independently of the Lower Acheulean of Africa, whose estimated age does not rise before 1.76 Ma. It should also be noted that on the neighboring territory of Georgia about the same time when appeared the Acheulean culture in Armenia, the Oldowan Dmanisi site already existed.     

Nouvelles espèces de dasycladales du crétacé inférieur de provence (S.E. France)

In the Lower Cretaceous of Provence Cylindroporella faronensis n. sp. and Cylindroporella massiliana n. sp. represent small size species with a limited number of branches. The former ranges from the Middle (or Lower p.p. ?) Berriasian to the Lower Valanginian, the latter is found in the Lower Hauterivian, but could appear earlier in other regions. Clypeina isabellae n. sp. is also a small size form with a fibrous, yellowish microstructure, close to Clypeina sulcata, it is restricted to the Middle (or Lower p.p. ?) and Upper Berriasian. Besides their biostratigraphic and palaeobiogeographic potential value this material from Provence is also interesting from an evolutionary point of view. At generic levels it shows distinctive patterns relatively to the “Cope law”.     

Ostéologie et affinités de Trematochampsa taqueti (Crocodylia,Mesosuchia) du Sénonien inférieur d'In Beceten (République du Niger)

Among the abundant remains of Mesosuchia that have been yielded by the early Senonian locality of In Beceten (Niger), the most numerous belong to the species Trematochampsa taquetiBuffetaut, 1974. The osteology of this species is described here. This medium-sized crocodilian, with a moderately elongated skull, is characterized, among other features, by its antorbital fenestra, its surangular-quadratojugal articulation, its slightly displaced post-orbital pillar, its teeth with wrinkled enamel, and its amphicoelous vertebrae. In its general outlook, this animal is rather reminiscent of the Goniopholidae, from the Upper Jurassic and the Cretaceous of Laurasia, but it is more primitive than them, and resemblances are probably due to convergence phenomena. The family Trematochampsidae is probably essentially Gondwanian, and could persist until the Senonian thanks to a certain isolation from Laurasia, where more progressive Crocodylia became predominant much earlier than in Africa and South America.