An ammonite–fish association from the Kimmeridgian (Upper Jurassic) of La Rochelle, western France

A partially disarticulated actinopterygian fish preserved in a large three-dimensional ammonite body chamber is described from the Kimmeridgian of western France. Taphonomic observations on the degree of preservation of the fish and the development of epibiont organisms on the inner wall of the shell indicate a rather long time interval before sediment totally filled the body chamber. The fish, referred to an indeterminate Macrosemiidae, probably used this empty ammonite ( Rasenioides , Aulacostephanidae) shell as a refuge, or possibly for spawning and/or brooding. It can be assumed that ammonite shells may have constituted common shelters for demersal fishes living in an open-marine shelf environment, near to a muddy bottom devoid of rocks.     

First Jurassic dinosaur tracksite from Guizhou Province,China: morphology,trackmaker and paleoecology

Abstract

Sauropod tracks from the Early Jurassic Maanshan Member of the Ziliujing Formation in the Dazhuanwan area of Guizhou represent the first Jurassic dinosaur track record for this province. The best preserved and longest trackway is narrow gauge (Brontopodus type), and indicates a relatively small trackmaker (footprint length ~35.0 cm). In conjunction with sauropodomorph skeletal remains these tracks suggest that basal sauropodomorphs and primitive sauropods coexisted in this region during the Early Jurassic. This pattern is same in the Lufeng and Sichuan basins. Thus, sauropod tracks from southwest China are diverse in the Early Jurassic, and include narrow gauge Parabrontopodus, wide gauge Brontopodus-type, and basal sauropodomorph tracks.     

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.     

Protoglobigérines et Oberhauserellidae (Foraminifères) du Bajocien-Bathonien du Jura méridional, France

A detailed investigation of the Bajocian-Bathonian protoglobigerinids and other globigerina-like foraminifera of the Southern Jura Mountains reveals an unsuspected diversity, with seven species of Conoglobigerinidae and two species of Oberhauserellidae. The discovery of two umbilical apertures in Oberhauserella as well as in some Conoglobigerina questions the generic taxonomy and raises the problem of comparisons with literature. For these reasons, five new species have been proposed: Oberhauserellaparocula and O. aff. parocula (with two apertures), “Conoglobigerina”trilocula and “C”.biapertura (with two apertures), C.solaperta and C.pupa. We demonstrate that Globuligerinabalakhmatovae (Morozova, 1961) (here emended) has a small globuligerine aperture as well as G. aff. dagestanica (Morozova, 1961). Despite the different taxonomic concepts, the Southern Jura Mountains associations, that are typical of the epicontinental platform, most closely match those of the Dagestan in the Caucasus. They clearly differ from those of the oceanic Tethys.     

A sauropod dinosaur megatracksite from the Late Jurassic of northern Switzerland

The largest known sauropod trackway site from the Upper Jurassic in Europe has been found in the northern Jura Mountains of Switzerland. Since the initial discovery of the site in 1988, detailed ichno‐facies mapping of the sites has been undertaken and completed. Six separate sites (from 5 to 45km apart) have been located to date; the largest one, displaying 345 single imprints, extends over a surface of 7000 m². As all of the reported sites occur within the same bed, these vertebrate prints form a megatracksite covering an area of more than 360 km². All localities are stratigraphically within the Reuchenette Formation. Two biostratigraphically diagnostic ammonites have been found within the sequence (Aulacostephanus; Gravesia), indicating an Upper Kimmeridgian age (sensu gallico). In the easternmost sites, imprints occur on mud‐cracked tidal pond deposits, whereas the western tracksites are found in supratidal algal marsh deposits. The track‐bearing horizon is immediately below a trans‐gressive event at all the sites, suggesting that the ichnofaunas represent dinosaur activity during a relative sea‐level low‐stand. Footprint size and morphology, as well as trackway dimensions, suggest that the track producers belong to the largest sauropods yet recorded in the European Jurassic, closely resembling the Breviparopus tracks from the Middle Jurassic of Morocco.     

The lithographic limestones of Cerin (southern Jura Mountains,France). A synthetic approach and environmental interpretation

The lithographic limestones of the Cerin quarry (southern French Jura Mountains), of Late Kimmeridgian age, were famous during the 19th century for their quality and consequently the quarry was intensely exploited. From 1975 to 1994, scientific excavations were carried out in these limestones in order to investigate the depositional environment, the burial of organisms and their taphonomy. A large set of data was collected about various organisms, unusual locomotion tracks, microbial mats and emersion structures. This led to a new interpretation of the environment as a laguna overlying a previously emergent and eroded coral reef. This laguna was episodically connected to the sea by temporary channels, during storms. Lime mud was supplied both from the sea and from the surrounding emergent areas. Most organisms, both marine and terrestrial, were transported, trapped, mixed and buried in the laguna. After death, the preservation of the carcasses was favoured by the presence of microbial mats providing superficial anoxic conditions and protecting them from decaying.     

La migration de la plate-forme urgonienne entre le Jura plissé et les Chaînes subalpines septentrionales (France, Suisse)

The stratigraphic study of the Urgonian carbonate platform presented here was carried out on a directed transversal NW-SE and passing by Geneva. This transversal extends on 100 km length; it lies between the face of the “folded Jura” (Champagnole, the Jura) and the septentrional subalpine chains (Aravis, Haute-Savoie). Essentially based on the biostratigraphy (ammonites, orbitolinids, echinids) and on sequence stratigraphy, this study illustrates the progradation of the Urgonian platform from the “folded Jura” (top of the Lower Hauterivian) to the Aravais chain (lowermost Barremian).     

Poekilopleuron bucklandii, the theropod dinosaur from the Middle Jurassic (Bathonian) of Normandy

Poekilopleuron bucklandii , described by Eudes–Deslongchamps in 1838, is one of the earliest discovered dinosaurs. Although incomplete, it is one of the best preserved Middle Jurassic theropods known from Europe. Unfortunately, the only specimen of P. bucklandii , housed in the Musée de la Faculté des Sciences de Caen, was destroyed during World War II. However, casts of some parts of the type skeleton have been found in the collections of the Museum National d'Histoire Naturelle, Paris. These casts and Eudes–Deslongchamps' monograph are used to redescribe the specimen. Poekilopleuron shares one synapomorphy with the Spinosauroidea and we tentatively assign it to that clade. The possible synonymy between Poekilopleuron and Megalosaurus is examined and we conclude that Megalosaurus is a nomen dubium and that the name should be restricted to the type dentary.     

Two new dinosaur tracksites from the Lower Cretaceous Jiaguan Formation of Sichuan Basin,China: specific preservation and ichnotaxonomy

Two new dinosaur tracksites are reported from the Lower Cretaceous Jiaguan Formation in the Sichuan Basin, Qijiang District of Chongqing. These are the Gaoqing-Yongsheng and the Huibu tracksites, which represent the 13th and 14th reports from this formation. The Gaoqing-Yongsheng tracksite reveals the trackway of a large biped (ornithopod) in association with isolated sauropod tracks and large indeterminate undertracks with radial cracks. These features are preserved as natural casts with pebble infillings in a coarse, cross bedded and very thick bedded sandstone sequence. The Huibu tracksite reveals isolated theropod tracks and ornithopod tracks, the latter having a quadripartite, Caririchnium-like morphology, preserved in a thin bedded sandstone sequence with intercalated mudstone.     

Lebensspuren von Meersauriern und ihren Beutetieren im mittleren Jura (Callovien) von Liesberg, Schweiz

Summary Numerous gutter-like furrows, up to 60 cm wide and up to 9 m long are preserved at the interface “Macrocephalus Beds”/“Callovian Marl” over a surface of 20 by 200 m. They are interpreted as feeding traces made by large marine vertebrates, most likely plesiosaurs and ichthyosaurs searching for food in the lime mud of the shallow Middle Jurassic sea floor. Possible prey animals were infaunal invertebrates (crustaceans) which produced an intricate meshwork of burrows (mainlyRhizocorallium irregulare andThalassinoides) in the bottom sediments, as well as infaunal bivalves. Evidence from cololites of predatory pelagic reptiles (ichthyosaurs, plesiosaurs) as well as reptile regurgitalites indicate that these animals fed not only on fast-swimming vertebrates and cephalopods but also on epi- and endobenthic invertebrates. In addition, the cololites show that the predators ingested considerable amounts of bottom sediment. Different sizes and shapes of the traces suggest that the gutters were produced by different reptiles or age groups. Candidates for the widest gutters are pliosaurs. Of the marine vertebrates known from Jurassic time, only the snout of adult pliosaurs of the genusLiopleurodon was broad enough to produce gutters more than 40 cm wide. Smaller, less than 15 cm wide gutters, could have been made by plesiosauroids or by the narrow pointed snouts of ichthyosaurs. Almost identical traces described from the Oxfordian of Spain and similar but smaller traces from the Lower Devonian of Prague are equally interpreted as feeding traces on the sea floor. Feeding traces of vertebrates in bottom sediments may give detailed information on the hunting behaviour of the predators. However, the attribution of the traces to definite vertebrate taxa remains uncertain.

     

Firewood management and woodland exploitation during the late Neolithic at Lac de Chalain (Jura,France)

The paper presents results of the charcoal analysis from the lakeshore settlement of Chalain 4 in the French Jura (Dép. Franche-Comté), dated by dendrochronology from 3040 to 3000 bc. The investigated material comes from waterlogged organic layers (excluding fire events) where charcoals are assumed to be the residues of domestic fires only. The anthracological (charcoal) analysis reveals a complex domestic firewood management in balance with the social organisation and the technical and economic systems of the settlement. This firewood economy is characterised by the avoidance of wood species intended for other activities, such as building or foddering, and by the preferential use of wood less than 10 cm in diameter. The areas from which firewood was obtained are also connected to woodland clearance for cultivated land, which suggests that firewood was gathered along the paths, which were travelled daily.     

Depositional sequences in the Kimmeridgian of the Vocontian Basin (France) controlled by carbonate export from shallow-water platforms

Detailed sedimentological analyses and sequential and cyclostratigraphic interpretations in the Kimmeridgian of the Swiss Jura and the Vocontian Basin lead to a high-resolution correlation from the platform to the basin where the biostratigraphy is well established. Several orders of depositional sequences are defined. Their duration is estimated from the time frame given in the sequence-chronostratigraphic chart of Hardenbol et al. (1998). It is suggested that an elementary sequence formed in tune with the 20 ky precession cycle. Small-scale and medium-scale sequences correspond to the 100 and 400 ky eccentricity cycles, respectively. The platform-to-basin correlation shows that the composition of the hemipelagic and pelagic deposits depends to a large part on cyclical variations of carbonate production in shallow-marine environments and subsequent export to the basin. The distribution of thick versus thin marl-limestone alternations and carbonate-dominated versus marl-dominated intervals observed in the basinal sections is explained by the superposition of high- and low-frequency sea-level changes that controlled the carbonate productivity on the platform and the export potential of carbonate mud to the basin.     

Evolutionary patterns in the terebratulid genus Caryona Cooper (Brachiopoda,Jurassic of France)

The study of ontogenetic and morphological changes in different species of the brachiopod genus Caryona COOPER (Terebratulidae) from the Lower Callovian‐Lower Oxfordian of northern France shows a succession (and an interference) of processes which vary according to the characters studied. This is an example of “mosaic evolution”;. The ontogenetic changes result from heterochrony, especially acceleration and hypermorphism. The main phylogenetic tendency is peramorphosis in most characters. This evolutionary pattern agrees with phyletic gradualism.

Moreover, analysis of the internal characters demonstrates the limited value of these in discrimination of the various genera.     

Development and eustatic control of an Upper Jurassic reef complex (Saint Germain-de-Joux,Eastern France)

Summary This study consists of a sedimentological and diagenetical analysis of reef facies from the Upper Kimmeridgian (sensu gallico). The investigated deposits are situated in eastern France, about fifty kilometres west of the city of Geneva (Switzerland). The reef complex is a fine example of vertical development and facies differentiation. It is subdivided into two distinct sequences by a perforated hardground horizon and sand shoals. The onset of the first reef sequence is characterized by a pioneer growth stage followed by up to 20 m of reef-core and-flank facies. Corals forming the reef-core are typically the ramose variety ofCalamophylliopsis flabellum. The second reef sequence has a reef-core with an average thickness of about 5 m. Corals, however, display much more varied morphologies, and in some areas massive rudist (Heterodiceras) build-ups occur. Development of the second reef sequence was seriously weakened by a storm which produced a 2 m thick accumulation of coral rubble. A shallowing-upwards trend gradually leads to the formation of beach deposits, followed by a newly detected black-pebble horizon. Diagenesis is an important aspect of the reef complex. Especially noteworthy is the dolomitization of certain horizons. At the base of the reef formation, the passage of the phreatic mixing zone provoked invasive dolomitization in large irregular patches (probably deposits richer in Mg-calcite). Some of the beds above the black-pebble horizon, in particular a deposit of accumulated microbial mats, are also dolomitized. In this case, dolomitization is stratiform and is interpreted as having precipitated under conditions of evaporative pumping. The sedimentary record clearly shows the imprint of eustasy. The reef complex was initiated during a transgressive cycle and the hardground found between the two reef sequences is interpreted as a maximum flooding surface (mfs). At the top of the sequence, the horizon overlain by the black-pebble conglomerate is believed to represent the new sequence boundary SB140. Other significant features identified from the St. Germain-de-Joux deposits include the discovery of a new foraminifera,Troglotella incrustans, which is only marginally covered here but is the topic of another paper (Wernli & Fookes, 1992); the subdivision of the first coralligenous level defined byPelletier (1953) into two reef sequences; and a proposition to redefine the ‘Calcaires de la Semine’ (Bernier, 1984). The investigations carried out in the past on the Kimmeridgian deposits in the area of St. Germain-de-Joux were mostly based on stratigraphy and palaeontology. These reefs are among the finest known in the Jura Mountains, but no thorough study had been made on their sedimentological aspects. The aim of this study is to fill this void and also to clarify the more confusing aspects of local stratigraphy (paper based onFookes, 1991).     

A nearly complete skeleton of an early juvenile diplodocid (Dinosauria: Sauropoda) from the Lower Morrison Formation (Late Jurassic) of north central Wyoming and its implications for early ontogeny and pneumaticity in sauropods

A nearly complete skeleton of a juvenile sauropod from the Lower Morrison Formation (Late Jurassic, Kimmeridgian) of the Howe Ranch in Bighorn County, Wyoming is described. The specimen consists of articulated mid-cervical to mid-caudal vertebrae and most appendicular bones, but cranial and mandibular elements are missing. The shoulder height is approximately 67 cm, and the total body length is estimated to be less than 200 cm. Besides the body size, the following morphological features indicate that this specimen is an early juvenile; (1) unfused centra and neural arches in presacral, sacral and first to ninth caudal vertebrae, (2) unfused coracoid and scapula, (3) open coracoid foramen, and (4) relatively smooth articular surfaces on the limb, wrist, and ankle bones. A large scapula, short neck and tail and elongate forelimb bones relative to overall body size demonstrate relative growth. A thin-section of the mid-shaft of a femur shows a lack of annual growth lines, indicating an early juvenile individual possibly younger than a few years old. Pneumatic structures in the vertebral column of the specimen SMA 0009 show that pneumatisation of the postcranial skeleton had already started in this individual, giving new insights in the early ontogenetic development of vertebral pneumaticity in sauropods.

The specimen exhibits a number of diplodocid features (e.g., very elongate slender scapular blade with a gradually dorsoventrally expanded distal end, a total of nine dorsal vertebrae, presence of the posterior centroparapophyseal lamina in the posterior dorsal vertebrae). Although a few diplodocid taxa, Diplodocus, cf. Apatosaurus, and cf. Barosaurus, are known from several fossil sites near the Howe Ranch, identification of this specimen, even at a generic level, is difficult due to a large degree of ontogenetic variation.     

A modern-type Kimmeridgian reef (Ota Limestone,Portugal): Implications for Jurassic reef models

Upper Jurassic reefs rich in microbial crusts generally appear in deeper (sponge—‘algal’ crust reefs) or in very shallow but protected settings (coral or coral-coralline sponge meadows with ‘algal’ crusts). Upper Jurassic high-energy reefs (coral reefs and coral-stromatoporoid reefs) normally lack major participation of microbial crusts but rather represent huge bioclastic piles with only minor framestone patches preserved. An exception to this rule is represented by the high-energy, coral-‘algal’ Ota Reef from the Kimmeridgian of the Lusitanian Basin (Portugal). The narrow Ota Reef tract rims a small intra-basinal carbonate platform exhibiting perfect facies zonation (from W to E: Reef tract, back reef sands, peritidal belt, low-energy shallow lagoon). The reef is dominated by massive corals (Thamnasteria, Microsolena, Stylina). Complete preservation of coral framework is rare: like other Upper Jurassic high-energy reefs, the Ota Reef is very rich in debris; however, this debris is largely stabilized by algal and microbial crusts, what contrasts the other examples and gives the Ota Reef the appearance of a typical modern high-energy coral-melobesioid algal reef. Further similarities to modern reefs are the likely existence of a spur-and-groove system, the perfect sheltering of inner platform areas and the occurrence of small islands, as indicated by local blackenings and early vadose and karstic features.     

Teeth of enigmatic neoselachian sharks and an ornithischian dinosaur from the uppermost Triassic of Lons-le-Saunier (Jura, France)

Shark teeth and an ornithischian dinosaur tooth are described from a new palynologically dated Rhaetian locality at Lons-le-Saunier (Jura, France). The structure of the enameloid of the teeth ofSynechodus rhaeticus has been studied, but this appears quite different from the usual pattern seen in neoselachian sharks, making the precise relationships of this species difficult to determine. On the other hand,‘Hybodus’ minor, which has long be thought to be a hybodont shark, is included among the Synechodontiformes. The find of the tooth of an ornithischian dinosaur is also reported. Study of the Lonsle-Saunier site seems to indicate a change in the marine faunas during the Rhaetian transgression, preferentially affecting the neoselachian sharks, which increase in abundance, and thedurophasous bony fishes, which become dominated bySareodon tomicus.     

Microbial encrustations from the Middle Oxfordian-earliest Kimmeridgian lithofacies in the Prebetic Zone (Betic Cordillera, southern Spain): characterization, distribution and controlling factors

Two main types of microbial encrustation were identified in Middle Oxfordian to lowermost Kimmeridgian deposits in the Prebetic Zone (southern Spain), showing existing relationships between skeletal content, fabric and morphology of these organosedimentary structures. Laminated planar and concentric encrustations relate to peloidal fabrics (mainly constituted of microbes = microbial laminated fabrics s. str. and microbial oncoids s. str.), as well as to dense microbial fabrics periodically colonized by encrusting foraminifera (microbial laminated fabrics with nubeculariids and microbial oncoids with nubeculariids). Sedimentation rates, substrate stability and grain size, as well as illumination, influenced microbial growth pattern as major controlling factors in low-energy conditions, and forced palaeogeographic and stratigraphic patterns of distribution. Significant encrustation was identified in terrigenous-poor lithofacies from the middle (Transversarium-Bifurcatus zones) to the outer (Transversarium-Bimammatum zones) shelf in the Prebetic Zone. Rare-to-absent encrustation characterized terrigenous-rich deposits (Bimammatum and Planula zones) in the area.