A new Late Jurassic species of the rare synechodontiform shark, <Emphasis Type="Italic">Welcommia</Emphasis> (Chondrichthyes,Neoselachii)

A new Jurassic species of the very rare and incompletely known synechodontiform shark, Welcommia, is described. The new species, Welcommia cappettai, is represented only by a single tooth, precluding reconstruction of its dentition in detail. Nevertheless, this specimen provides sufficient information and characteristics to establish its taxonomic status. Welcommia cappettai n. sp. occurs in the middle Oxfordian (Upper Jurassic) of south-western Germany. This is the first unambiguous record and named species of Welcommia from the Late Jurassic, substantially reducing the rather large gap in the fossil record of this synechodontiform taxon. So far, two Welcommia species from the Lower Jurassic of Belgium and the Lower Cretaceous of southern France have been described. An additional, still unnamed species seemingly occurs in the Oxfordian of southern France. The new species has plesiomorphic and apomorphic characteristics and, probably, an intermediate dental pattern that tentatively enables reconstruction of evolutionary trends in the dentition of this shark from small and compact teeth with broad, almost triangular cusps, to mesio-distally lengthened teeth with elongated mesial heels resulting in an extremely extended mesial cutting edge in addition to more delicate cusp and cusplets in advanced forms. These differences might be related to improved feeding mechanisms. It is hypothesized that Welcommia was predominantly a component of the Mediterranean faunal province. The disappearance of Welcommia in the Early Cretaceous remains ambiguous and might be related to competition by other sharks, for example hexanchiforms, or might represent a collecting bias and/or taxonomic misidentification of isolated teeth.     

Stratigraphie du Jurassique supérieur du djebel Bechtout au Nord-Ouest de tiaret (Bordure sud-tellienne,Algérie); Comparaison avec le Bou Rheddou

The study of the Upper Jurassic of the Bechtout Mountain (Southern Tellian border) allows us to distinguish five formations and to precise their age assignment owing to new collections of ammonites. Previous stratigraphic assignments are modified. Stratigraphic and sedimentologic data give evidence that each of the five Bechtout formations can be correlated with those encountered in the Bou Rheddou Mountain. As in the Bou Rheddou, first beds with ammonites are Middle Oxfordian in age. The Oxfordian «Ammonitico rosso facies begins in the Transversarium Zone up to the Planula Zone. The uppermost formation (Calcaires médians du Bou Rheddou) that begins in the Upper Oxfordian (Planula Zone) is essentially Kimmeridgian what causes us to exclude the time range Portlandian-Lower Cretaceous previously assumed.     

Radiation précoce des coniferes Taxodiaceae et bois affines du Jurassique de France

Three Jurassic fossil-wood taxa from France have been investigated, Taxodioxylon lemoignei n.sp. from the Oxfordian, Prototaxodioxylon romanensis Philippe from the Pliensbachian, and P. sp. from the Hettangian. Wood of this type, prior to the Late Cretaceous, is reviewed. The Oxfordian wood shows a structure characteristic of a Taxodiaceae, previously unknown before the Late Cretaceous. It is well differentiated from contemporaneous woods of Cupressaceae. The systematic position of the Liassic forms, with mixed type of pitting, remains more arguable. These taxodiaceous woods, along with known reproductive structures, reinforce the idea that this family was well separated from Cupressaceae already in the Middle Jurassic. *** Fossil wood, Jurassic, France, Taxodiaceae.     

Sur l'origine du genre Microceratina Swanson, 1980 (Ostracoda, Eucytherurinae) et sa présence téthysienne dès le Jurassique supérieur

The discovery in the uppermost Jurassic of Lebanon of a species of the ostracod genus Microceratina Swanson, 1980 (Eucytherurinae), of which the oldest known species was until now of Maastrichtian age, confirms the Tethyan origin of this genus. Two new species are created: Microceratina bhannesensis nov. sp. from the Upper Jurassic (Kimmeridgian) of Lebanon, and Microceratina azazoulensis nov. sp. from the Cenomanian of Morocco. The genera Chapmanicytherura Weaver, 1982 and Erratacytheridea Herrig et al., 1997, are considered as probable junior synonyms of Microceratina. An exhaustive bibliographical analysis allowed to identifying several other Cretaceous species susceptible to be assigned to the genus Microceratina.     

First Jurassic occurence of Enoploclytia M’Coy, 1849 (Crustacea: Decapoda: Erymidae)

Among the Erymidae Van Straelen, 1925, known as early as the Late Permian (Changhsingian) and widespread in the Jurassic, the genus Enoploclytia M’Coy, 1849 seems to have a late appearance because of its lack before the Cretaceous. Until now, the oldest representative was E. augustobonae Devillez, Charbonnier, Hy?ný and Leroy, 2016 from the Early Cretaceous (Barremian) of the eastern Paris basin (France). However, a new fossil collected in Normandy (France), showing the typical carapace groove pattern of Enoploclytia, attests the presence of the genus in the Late Jurassic (Oxfordian).     

Stratigraphie et sédimentologie des « Couches rouges » continentales du Jurassique-Crétacé du Haut Atlas central (Maroc) : implications paléogéographiques et géodynamiques

In several synclines of the central High Atlas, the “Redbeds” following the closure of the marine Tethyan Atlasic trough during the Middle Jurassic are constituted by three successive formations or units of continental deposits dated recently with biostratigraphical elements. Some micropaleontological markers, mainly charophytes and ostracods, allow to precise the stratigraphy in agreement with a Bathonian-?Callovian assignment for the lower unit (Guettioua Formation), and in dating the middle and upper units. The Upper Jurassic, mainly the Kimmeridgian, is developed in the lower part of the middle unit (Iouaridene Formation). The Barremian has been recognized in this middle unit and in the upper unit (Jbel Sidal Formation). The Jurassic/Cretaceous boundary is thus delimited for the first time with micropaleontological data. These new data are very significant for the Atlasic history during the Mesozoic. The basaltic flows inserted in the continental Jurassic-Cretaceous deposits of the central High Atlas result from two separate events in the Middle Jurassic and in the Barremian. The tectogenesis in the basins is characterized by a polyphase process including notably a synsedimentary tectonic activity conspicuous in the Barremian. The evidence of marine to brackish intercalations allows moreover to date the first Cretaceous transgressive event on the NW boundary of the High Atlas during the Lower Barremian and to consider an Atlantic paleogeographical interaction. SW margin of the Tethyan trough in the Lower and Middle Jurassic, the central High Atlas is merged with the margin of the central Atlantic Ocean during the Lower Cretaceous.     

Tithonia oxfordiana,a new irregular echinoid associated with Jurassic seep deposits in south‐east France

Abstract: The infaunal irregular echinoid, Tithonia oxfordiana, is described and compared to congeneric species previously described from Upper Jurassic and lowermost Cretaceous strata. This new species characterizes a monospecific echinoid assemblage, which occurs only in some places where deep‐marine middle Oxfordian deposits are exposed in south‐east France. Specimens are closely packed and clearly concentrated at the top of small carbonate chemoherms; a close connection of the echinoids with the emission of reduced chemicals, which were oxidized by chemoautotrophic bacteria, is highly probable. Based on general test shape and plate architecture, T. oxfordiana probably was a deposit feeder on chemosynthetic organic matter produced by such bacteria. In view of the fact that T. oxfordiana is the sole species of the Jurassic genus Tithonia known from Oxfordian strata, it is postulated that chemoherms possibly acted as refugia for these peculiar echinoids, which have an episodic record between the Callovian and Valanginian.     

Palynostratigraphie du Callovien-Oxfordien (Jurassique) dans les Terres noires, sud-est France

The Terre noires are monotonous sedimentary deposits comprising thick, dark marls and thin carbonaceous layers. They constitute a lithostratigraphical group known in the major part of the SE French Basin. In the East of this basin this group, dated from late Bajocian to mid Oxfordian, is well developed; on the other hand on the West, it is reduced until it disappears locally on the border of the Massif Central. In the East, the succession is precisely dated by ammonites, whereas in the west, ammonites are not consistently present, and do not permit the same precision. Analysis of dinoflagellate cyst assemblages, at the Callovian-Oxfordian boundary, show that it is possible to correlate the eastern to the western succession. Two marker species allow the correlation of four outcrop sections. The first index, Wanaea fimbriata, is well known; its first appearance datum is exactly at the Callovian-Oxfordian limit in the Boreal and Mediterranean realms. It is the index taxon of the palynological parazone Wfi. The second index, Stephanelytron ceto, an endemic taxon in the SE French, has its last appearance datum within the Scarburghense horizon, the second subzone of the oldest zone of the Oxfordian (Mariae zone). The first section studied was sampled in the east part of the basin (Hautes Alpes department). It corresponds to the maxima of marine deposits and is used as the palynostratigraphical reference. The three other sections analyzed, sampled in the west part of the basin (Ardèche department) where marine deposits are more condensed, are correlated and dated due to dinoflagellate cyst markers observed in the reference section. These results indicate that dinoflagellate cysts are a reliable correlation tool. Batiacasphaera rugosa (Courtinat, 1980) nov. comb is proposed.     

Armored dinosaurs(Ornithischia: Ankylosauria)) from the Middle and Upper Jurassic of England

Hitherto the earliest positive record of ankylosaurs(armored dinosaurs) has been from beds well up in the Lower Cretaceous; in fact, however, specimens referable to the ankylosaurian family Nodosauridae are present in the Middle and Upper Jurassic of England: from the Middle Callovian [partial mandible Sarcolestes leedsiLydekker]], the Upper Oxfordian [femur Cryptodraco eumerus (Seeley)), maxilla Priodontognathus phillipsii (Seeley))], and the Upper Tithonian [caudal vertebra, tooth]. The Tithonian tooth and those of Priodontognathus are large and similar to those of the nodosaurids Priconodon and Sauropelta (Lower Cretaceous, U.S.A.). The incomplete mandible of Sarcolestes is similar to that of Sauropelta with a dermal scute fused to the lateral surface, and a tooth row extending to the anterior end of the jaw; an unusual feature is the caniniform first tooth. The quadrupedal ankylosaurs and stegosaurs probably represent separate evolutionary lines that extend back at least into the Lower Jurassic, and both lines probably evolved from ornithopod dinosaurs that were bipedal. Nodosaurid ankylosaurs occur in Europe from the Middle Jurassic to Late Cretaceous and probably reached North America via a filter route in the early Cretaceous.     

Una nueva especie de Weltrichia (Bennettitales) del Jurásico Medio de la Formación Tecomazuchil (Oaxaca, México)

A new species of Weltrichia (Williamsoniaceae: Bennettitales) is described from the Middle Jurassic of Oaxaca. The specimens come from the Tecomazuchil Formation in the Ayuquila region, at the border between the Oaxaca and Puebla states. Fossils are preserved as impressions and compressions, in a fine-grained sublitharenite sequence deposited in a fluvial environment. Preserved diagnostic characters include: large size; a cup-shaped receptacle showing seven radially arranged and basically fused microsporophylls bearing synangia. Microsporophylls are ornamented with longitudinal striations and fine brittled hairs on the edge of their wide base, and taper into a narrow distal tip. In the adaxial part of the microsporophylls seven to nine synangia are observed. These characters differentiate the new species Weltrichia mixtequensis from all previously recorded species from Mexico or elsewhere. The presence of this new species in the Middle Jurassic strata of the Ayuquila region add to the scarce fossil record of microsporangiate structures in the Jurassic flora of Mexico.     

Jurassic mountain building and Mesozoic-Cenozoic geodynamic evolution of the Northern Calcareous Alps as proven in the Berchtesgaden Alps (Germany)

New data from the Berchtesgaden Alps result in a reconstruction of the Mesozoic-Cenozoic geodynamic history of the Northern Calcareous Alps. The closure of the western part of the Neotethys Ocean started in the late Early Jurassic and is evidenced by the onset of thick clay-rich sediments in the outer shelf area (=Hallstatt realm). The Middle to early Late Jurassic contraction is documented by the migration of trench-like basins formed in front of a propagating thrust belt. Due to ophiolite obduction, these basins propagated from the outer shelf area, forming there the Bajocian to Oxfordian Hallstatt Mélange, to the Hauptdolomit/Dachstein platform area, where the Oxfordian Rofan and Tauglboden Mélanges were formed. The basins were separated by nappe fronts forming structural highs. This scenario mirrors syn-orogenic erosion and deposition in an evolving thrust belt. Active basin formation and nappe thrusting ended around the Oxfordian/Kimmeridgian boundary, which was followed by the onset of carbonate platforms on structural highs prograding towards the former basins in latest Oxfordian to Early Tithonian time. Underfilled basins remained between the platforms. Rapid deepening around the Early/Late Tithonian boundary was induced by extension due to mountain uplift and resulted in the reconfiguration of the platforms and basins related to normal and probably strike-slip faults. Erosion of the uplifted nappe stack including obducted ophiolites caused final drowning and demise of the platforms in the Berriasian. The remaining Early Cretaceous basins were filled up with molasse sediments including siliciclastics until Aptian. Around the Early/Late Cretaceous boundary again extension and strike-slip movements started, followed by Eocene thrusting and Miocene strike-slip movements with block rotations. These younger tectonic movements destroyed the Triassic to Early Cretaceous palaeogeography and arranged the modern block configuration. The described Jurassic to Early Cretaceous history corresponds with that of the Western Carpathians, the Dinarides, and the Albanides, where (1) age dating of the metamorphic soles prove late Early to Middle Jurassic inneroceanic thrusting followed by late Middle to early Late Jurassic ophiolite obduction, (2) Kimmeridgian to Tithonian shallow-water platforms formed on top of the obducted ophiolites, and (3) latest Jurassic to Early Cretaceous sediments show postorogenic character. Therefore, we correlate the Jurassic geodynamic evolution of the Northern Calcareous Alps with the closure of the western part of the Neotethys Ocean.     

First description of axymyiid fossils (Insecta: Diptera: Axymyiidae)

Two species of fossil insects from the Daohugou Formation of Chifeng City in Nei Monggol Autonomous Region, northeastern China are described, and recognized as Psocites pectinatus (Hong, 1983) nov. emend., nov. transl. and P. fossilis nov. sp. They are the oldest representatives of the family Callovian or Axymyiidae, and first described of this family in the Mesozoic. Although early the age of the fly-bearing beds is controversial, it is probably Oxfordian or Kimmeridgian (Late Jurassic) rather than Early Cretaceous or Middle Jurassic.     

Le Crocodilien Steneosaurus (Mesosuchia,Teleosauridae) dans le Jurassique supérieur franc-comtois (Jura,France)

Two new fossil vertebrate localities have been discovered close to each other in the Upper Jurassic (Effingen beds, Upper Oxfordian) of the Southern Jura department (France). One of the localities have yielded an incomplete skeleton of the crocodilian Steneosaurus (including a well preserved skull), as well as fish remains and an abundant invertebrate fauna. The second locality has mainly yielded various fragmentary bones of Steneosaurus. This is the first discovery of well preserved crocodilian remains in the Oxfordian of the Jura.     

Répartition stratigraphique et biozones des kystes de dinoflagellés au passage Jurassique moyen–Jurassique supérieur (Bathonien supérieur–Oxfordien inférieur) dans le Bassin de Guercif,Maroc nord-oriental

Despite the stratigraphical significance of dinoflagellate cysts as reliable markers for correlating and dating Jurassic–Cretaceous strata, investigations into this palynomorph group in the southern Tethyan Realm, specifically northwest Africa, are sparse and somewhat parochial. Most research on Jurassic dinoflagellate cysts is focussed on European depocentres in the Boreal and Sub-Boreal realms. This study is on biostratigraphical data from two petroleum boreholes (MSD1 and KDH1) drilled during 1985 in the Guercif Basin, northeast Morocco by ONAREP (Office National de Recherche et d’Exploitation Pétrolier), now ONHYM (Office National des Hydrocarbures et des Mines). These boreholes penetrated a thick siliciclastic succession, attributed to the Middle and Upper Jurassic, below Miocene marls. Over sixty dinoflagellate cyst taxa were identified. Four dinoflagellate cyst biozones, named GI to GIV, are established for the late Bathonian to early Oxfordian interval. These biozones are defined on the basis of the first appearance datum (FAD) and/or the last appearance datum (LAD) of some biomarker taxa which have wide geographical distributions. These are: Ctenidodinium combazii and Ctenidodinium sellwoodii for the GI Biozone (late Bathonian–early Callovian); Ctenidodinium continuum and Meiourogonyaulax caytonensis for the GII Biozone (middle Callovian); Gonyaulacysta centriconnata and Wanaea thysanota for the GIII Biozone (late Callovian–earliest Oxfordian); and Liesbergia liesbergensis and Systematophora penicillata for the GIV Biozone (early Oxfordian). These biozones are correlated to those already established for the respective intervals in other palaeogeographic regions, such as the Boreal, Sub-boreal and Tethyan realms.     

Revidierte Systematik der Ostracoden im Oberjura und der basalen Kreide Ostdeutschlands

The Upper Jurassic and basal Cretaceous ostracod faunas of Northeastern Germany, which have not been sufficiently investigated and documented yet, are revised. The fauna, documented by stratigraphical tables and SEM-pictures, consists of 116 species from 36 genera, two species of which are new:Galliaecytheridea wienholzae n. sp. andRasthalmocythere keuppi n. sp. The biostratigraphical ränge of the taxa extends from the Oxfordian to the early Berriasian. A palaeobiogeographical correlation with the ostracod faunas of Northwestern Germany reveals close relationships between both areas concerning the stratigraphical range and assemblage of the fauna.     

Les Gregoryceras (Ammonitina) de l’Oxfordien moyen terminal et supérieur téthysien : révision systématique, biostratigraphie et évolution

In prolongation of the previous studies, the Gregoryceras Spath, 1924 (Ammonitina, Peltoceratina) species from the uppermost Middle Oxfordian (Rotoides sub-zone) to the Early Late Oxfordian (Bifurcatus zone), are revised. Sections providing most of the studied specimens in this work (Spain, Algeria, Tunisia) are described and dated based on faunal comparisons between Tethyan and Subtethyan domains. It appears that the best tool for correlations is the presence of the genus Gregoryceras, the succession of its species being similar for the two considered domains. It allows us to complete the biostratigraphic scale based on the Gregoryceras species succession, and parallel to the standard zonation. During this period the revised species of Gregoryceras are G. fouquei (Kilian, 1889) and G. pervinquieri (Spath, 1913). G. fouquei is only present in the Rotoides sub-zone (uppermost Middle Oxfordian), and not in the Stenocycloides sub-zone (early Late Oxfordian), where G. pervinquieri (Spath, 1913). A new species, G. benosmanae nov. sp. is described as the most recent species of the genus (Grossouvrei sub-zone). The evolution of the youngest species of Gregoryceras continues the peramorphocline described for older forms. Concerning a potential dimorphism, new data (size differences, umbilicus enlargement during growth) are particularly provided by G. pervinquieri.     

The oldest turtle from Portugal corresponding to the only pre-Kimmeridgian plesiochelyid (basal Eucryptodira) recognized at the generic level

A shell coming from an upper Oxfordian section of the Lusitanian Basin located in Alqueidão da Serra (Municipality of Porto de Mós, West Central Portugal) is here presented. It corresponds to the oldest remain of a turtle identified in Portugal. In fact, the record of Jurassic turtles identified in pre-Kimmeridgian levels of Europe is very scarce. The new specimen represents the second worldwide identification of a Plesiochelyid turtle (basal Eucryptodira) performed in pre-Kimmeridgian levels, being the only one recognized at generic level. Therefore, this specimen corresponds to the oldest identification of Craspedochelys, a genus well-represented in Kimmeridgian and Tithonian levels of several European countries. This finding contributes the first evidence on the synchronous coexistence of more than a member of Plesiochelyidae in pre-Kimmeridgian levels, which provides arguments to justify the relatively wide diversity known for this exclusively Jurassic clade during the Kimmeridgian and the Tithonian.     

Deux nouveaux sites à traces de pas dinosauroïdes dans la Formation Dolomitique de l’Hettangien de Lozère,Languedoc-Roussillon,France

Recent ichnological studies revealed two new localities showing dinosaur footprints in the Hettangian Dolomitic Formation from the Causses Basin, southern France. The traces are reported from the northern part of the basin, in Lozère, an area where Lower Jurassic dinosaur ichnites were poorly documented. The surfaces bearing footprints are characterized by a large number of traces. The ichnites are ascribed to Grallator (Hitchcock, 1858), Dilophosauripus (Welles, 1971) and Eubrontes (Hitchcock, 1845) whose trackmakers were theropods. Although numerous tracksites were previously described in the southern part of the Causses Basin, these three ichnotaxa are for the first time observed in association into the Dolomitic Formation.     

Calcareous nannofossil productivity and carbonate production across the Middle-Late Jurassic transition in the French Subalpine Basin

The distribution pattern of calcareous nannofossils was analysed across the Middle-Late Jurassic transition in the French Subalpine Basin (south-eastern France). This basin is characterized in the hemipelagic-pelagic domain by a continuous sedimentary succession, allowing a good biostratigraphic resolution for this time interval. The nannofossil assemblages are consistently dominated by Watznaueria britannica. However, major changes in trophic and paleoenvironmental conditions are recorded across the Middle-Late Jurassic transition. An increase in marine primary productivity and cooling of surface waters is recorded across the Callovian-Oxfordian boundary, as already shown in the higher latitude setting of the eastern Paris Basin. Increased precipitation and runoff under contrasting seasonal climatic conditions (monsoon-type) has led to eutrophication of marine surface waters in the French Subalpine Basin at this period. Then, decreased runoff and associated nutrients certainly linked to drier climatic conditions lead to a decrease in calcareous nannofossil productivity during the middle part of the Early Oxfordian (mariae-cordatum ammonite Zone transition). At the Early-Middle Oxfordian transition, more favourable conditions for the nannofossil community (warmer and mesotrophic surface waters) prevailed. The pelagic (nannofossil) carbonate contribution is limited, and the carbonate fraction is predominantly of nektonic/benthic origin at the Callovian-Oxfordian transition and of allochthonous origin from carbonate platforms at the Early Oxfordian-Middle Oxfordian transition.