Jean-Claude Gall

Réflexions critiques sur l'écologieet la systématique des Lingules actuelles et fossiles

Abstract New topics on ecology and systematics of recent and fossil Lingulids lead to an obvious revision of our knowledges on this zoological group. At first, the recent species need systematics and taxonomy on the bases of new described specific criteria (as, morphology of deltidial areas, muscle disposition); the results are briefly indicated. But, in fossil species, disorder and disparity of used characteristics are emphasized. The general conceiving on ecology of Lingulids are reviewed and discussed, especially on bathymetry and salinity; sediment and oxygenation conditions; taphocoenosis and lingulid «communities. On recent species, all these points are also studied, especially some ecological requirements (salinity, bathymetry, grain size), and mechanism of burrowing ability, burrow living positions in the sediments, as shell preservations after death and fossilization, to facilitate the paleobiotope interpretations. Recent animals are euryhalin, surviving at salinities from about 13 to 42‰; they could be considered as well adapted to waters with strong salinity fluctuations. They show preference to fine sand bottoms (lowest particle size about 40–60 μm). Their bathymetric distribution occurs between 0 and about 500 m (Lingula especially between 5–50 m; Glottidia 15–70 m). The isotherms 8–10°C seem to restrict their geographical and bathymetric distribution. Therefore, some post-palaeozoic lingulid bedsare studied or redescribed on the bases of the above discussed characteristics, and new interpretations on the environmental situation are given (Trias of Vosges Mountains; Oligocene from Japan; Eocene of London Basin). More caution must be used in study of fossil Lingulids that are not especially animals living in infralittoral bottoms with low salinity and deficient oxygenation, as generally accepted.

A giant Upper Jurassic turtle revealed by its trackways

Exceptional fossilization of large tetrapod swimming traces occurs in the Cerin Lagerstatte (Jura Mountains, France). These trackways are imprinted in Jurassic (Late Kimmeridgian) lagoonal fine-grained limestones and are attributed to giant turtles, which swam with a simultaneous movement of their forelimbs like the modern ones. These turtles swam in very shallow waters close to land, perhaps near a nesting area. As a major consequence, these new ichnologic data place the origin of true large marine turtles during the Jurassic period and not during the Cretaceous period as previously considered on the basis of skeletal remains.

The Ephemeridea (Insecta) from the Grès à Voltzia (early Middle Triassic) of the Vosges (NE France)

The study of the Ephemeridea (385 specimens) of theGrauvogel andGall collection from the Grès à Voltzia (early Middle Triassic) of the Vosges, NE France, enabled the description of two new genera based on wings and six new genera based on nymphs. The new monotypic wing genera areToxodotes coloratus n. gen. n. sp. (Toxodotidae n. fam.) andTriassodotes vogesiacus n. gen. n. sp. (family MisthodotidaeSellards). The Misthodotidae, known until now only from the Permian, crossed the Permian/Triassic boundary and did not seem to have been affected by the end-Permian biotic crisis. Apart from the genera based on wings, six new monotypic genera are represented by nymphs only:Triassoephemera punctata n. gen. n. sp. (Triassoephemeridae n. fam.);Voltziaephemera fossoria n. gen. n. sp. (Voltziaephemeridae n. fam.), the most common species in the Grès à Voltzia;Triassomanthus parvulus n. gen. n. sp. (Triassomanthidae n. fam.);Triassonurus doliiformis n. gen. n. sp. (family SiphlonuridaeUlmer), now the oldest record of this family;Minorella virgata n. gen. n. sp. (family undetermined);Vogesonympha ludovici n. gen. n. sp. (Vogesonymphidae n. fam., Pterygota incertae sedis). Additionally,Mesoplectopteron longipes (Handlirsch) (family MesoplectopteridaeDemoulin) which was described earlier, is also present in theGrauvogel &Gall collection. The morphology of the Ephemeridea nymphs, at least for some of them, enables the interpretation of their probable habitats and life conditions, and thus contributes to our knowledge of the Grès à Voltzia palaeoenvironment.KurzfassungDie Untersuchung der Ephemeridea (385 Exemplare) derGrauvogel undGall Sammlungen aus dem Grès à Voltzia (frühe Mittel-Trias) der Vogesen, NE Frankreich ermöglicht die Aufstellung und Beschreibung von zwei neuen monotypischen Gattungen basierend auf der Flügel-Morphologie und sechs neuen monotypischen Gattungen basierend auf den Nymphen. Die neuen Flügel-Gattungen sindToxodotes coloratus n. gen. n. sp. (Toxodotidae n. fam.) undTriassodotes vogesiacus n. gen. n. sp. (Familie Misthodotidae). Die Misthodotidae, bisher nur aus dem Perm bekannt, überschritten die Perm/Trias-Grenze und scheinen von der biotischen Krise am Ende des Perms nicht beeinflusst worden zu sein. Die 6 monotypischen auf Nymphen basierenden Gattungen sindTriassoephemera punctata n. gen. n. sp. (Triassoephemeridae n. fam.);Voltziaephemera fossoria n. gen. n. sp. (Voltziaephemeridae n. fam.), die häufigste Art im Grès à Voltzia;Triassomanthus parvulus n. gen. n. sp. (Triassomanthidae n. fam.);Triassonurus doliiformis n. gen. n. sp. (Familie SiphlonuridaeUlmer), der hiermit älteste Nachweis der Familie;Minorella virgata n. gen. n. sp. (Familie unbestimmt);Vogesonympha ludovici n. gen. n. sp. (Vogesonymphidae n. fam., Pterygota incertae sedis).Mesoplectopteron longipes (Handlirsch, 1918) (Familie MesoplectopteridaeDemoulin), bereits vorher beschrieben, ist in derGrauvogel &Gall Sammlung ebenfalls vertreten. Die Morphologie einiger Ephemeridea-Nymphen erlaubt die Interpretation ihres möglichen Habitats and ihrer Lebensweise und trägt damit zur Kenntnis der Umweltbedingungen während der Ablagerung des Grès à Voltzia bei.

La crise biologique du permien et la renaissance trisique

The most severe mass extinction of the Phanerozoic occurred by stages in the Permian and spanned several millions of years. The marine environments suffered the most since their ecosystems greatly collapsed under the joint effects of a great drop in sea level and general anoxic conditions in the ocean. On the land, arid conditions and several brief episodes of climatic cooling led to a great loss in biodiversity of the vertebrate fauna and flora and therefore in the ground cover by the plants, In contrast, the insects did not seem to be very much affected by the crisis. The recovery of the disturbed ecosystems at the beginning of the Triassic proceeded from refuges, such as the transitional environments between sea and emerged lands.

La plus ancienne sauterelle Tettigoniidae, Orthoptera (Trias, NE France): mimétisme ou exaptation?

KurzfassungTriassophyllum leopardii n. gen. n. sp. aus dem Oberen Buntsandstein (Voltziensandstein) der Vogesen (Frankreich) dürfte zu den Tettigoniidae gehören. Dieser Fund beweist, daß diese Familie auf das Mesozoikum (untere/mittlere Trias: unteres Anis) zurückgeht und nicht, wie bis jetzt angenommen, auf das Känozoikum.Das Vorderflügel-Geäder zeigt viele Ähnlichkeiten mit dem der Tettigoniidae und besonders mit dem der Pseudophyllinae, die heute nur in den Tropen vorkommen. Es suggeriert die Nachahmung von Angiospermen-Blättern. Da aber diese Pflanzen im Voltziensandstein fehlen, müssen andere Hypothesen in Betracht gezogen werden. Die scheinbare Blattanpassung könnte auch als Exaptation interpretiert werden.RésuméTriassophyllum leopardii n. gen. n. sp. du Grès à Voltzia (Buntsandstein supérieur) des Vosges (France), est représenté par des ailes qui ont pu être classées dans les Tettigoniidae. Cette découverte montre que l’ancienneté de cette famille remonte au début du Mésozoïque (Trias inférieur/ moyen: Anisien inférieur) et non au Cénozoíque, comme cela était admis jusqu’à présent.Le schéma nervuraire de ces ailes antérieures présente en effet beaucoup d’analogies avec celui des Tettigoniidae actuels et en particulier des Pseudophyllinae qui n’existent aujourd’hui que dans les zones intertropicales. Ce schéma nervuraire suggère un mimétisme foliaire en relation avec les angiospermes. Mais l’absence de ce type de plantes dans le Grès à Voltzia nous conduit à envisager d’autres hypothèses. Ce mimétisme apparent pourrait également résulter d’une exaptation.

Impact des écosystèmes microbiens sur la sédimentation. Impact of microbial ecosystems on sedimentation

Abstract The microbial communities which often give rise to the fine lamination in sediments are very diverse both in species composition (e.g. phototrophic and chemotrophic bacteria, fungi, algae) and metabolism (e.g. oxygenic and anoxygenic photosynthesis, organic and inorganic chemosynthesis, anaerobic and aerobic respiration, organic and inorganic fermentation). These microbial ecosystems have separated for more than 3.5 Ga (3500 m.y.). They intervene in the biostructuration of sediments by active mineral deposition, particle trapping and sediment stabilisation. They build bioconstructions (stromatolites, oncolites, oolites and microbial bioherms). Further they are active in a number of biogeochemical biomineralisation processes including phosphatogenesis, carbonate genesis and the formation of iron ore and sulfur deposits, and petroleum and kerogen. They are also active agents in the biocorrosion and bioerosion of sedimentary rocks under marine and terrestrial conditions. Since they have an enormous capacity for proliferation, microbial laminated communities invade new habitats, practically instantaneously where suitable energy sources and gradients for electron flow are available. In addition such microbial systems are excellent and sensitive paleoecological indicators. In order to study their impact on sedimentation and fossilisation a close collaboration between geologists and microbiologists is needed. Only in this way can the nature of fossil microbial ecosystems and the metabolisms that were at work be recognized and reconstructed.

A “stick insect-like” from the Triassic of the Vosges (France) (“pre-Tertiary Phasmatodea”)

Résumé Palaeochresmoda grauvogeli, new genus and species of “stick insect-like” is described from the Lower-Middle Triassic of France. It is the oldest known Prochresmodidae and probably “pre-Tertiary Phasmatodea”. The importance of phylogenetic analyses is emphasized for the estimations of the insect palaeobiodiversity and the crises that could have affected it.

Morphologie des constructions microbiennes en contexte de fan-delta Oligocène. Exemple du rift rhénan (Europe occidentale)

Abstract At the Eocene/Oligocene boundary a first paroxysmal phase of subsidence created the Rhine rift graben system. A lacustrine basin with variable salinity was formed in the graben. In the southern part of this basin a large fan-delta developed, extending northward along the graben axis. Microbial ecosystems settled on the fringe of the lake. In the paludal zone, they formed carbonate encrustations on living plants or detrital vegetal remains. Littoral carbonate facies occur as algal bioherms and stromatolitic reefs. In the distal lacustrine zone, a discrete nodular texture within the sediment reveals the microbial origin of micrite and gives the limestone a breccial pattern. All these facies illustrate the lateral zonation of the different types of constructions from fluvio-deltaic to lacustrine. In certain cases, the microbial coating on plants permits to reconstruct seasonal rhythms and the processes of substratum colonisation.

The underlying substrate ofthe Cerin Lithographic Limestones

Abstract The Cerin Lithographic Limestones do not cover a wide area. They correspond to numerous lagoon in-fillings of limited development, within a wide emerged area characterized by sandy (skeletal) limestones mainly of coral origin (Landaize Limestones). At the village of Cerin where an excavation for paleoecological studies is located, the sandy Landaize Limestones provide the lithographic limestone substrate. Their cementation is partly of supratidal and/or intertidal origin, but frequently shows phreatic freshwater features. Finally, microbial cements (bacteria or cyanobacteria) reflect a major process of lithification. The original substrate consisted of grainstones, the top of which was considerably eroded, producing uneven relief with steep slopes and even cliffs, sometimes reaching several metres in height. The erosion processes were probably mechanical in origin, but also biochemical (biokarst) and especially biological (bioerosion by grazing, boring and microbial erosion). Lime mud which produced the lithographic limestones filled the hollows between the substrate reliefs. Around areas where the uneven rocky substrate had steep gradients locally developed gravity flows occur. These are capped with microbial films which are affected by superficial slides showing more or less concentric or complex wavy structures. Locally, true slumps giving rolls and synsedimentary microfolds also occur.

Eichstätt and Cerin: Geochemical comparison and definition of two different plattenkalk types

Abstract Bed-by-bed analyses of a lateral set of profiles in the Eichstatt area, and of one profile of Cerin reveal some analogies and some differences. The analogies are: A.1) There appear three distinct lithofacies which differ in their contents of insolubles in 1 : 3 : 10 ratios. A.2) The 12 analyzed elements can be separated into 3 groups: a “clastic group” (Si, Al, K, Fe) with very similar trends in profile, caused by the detrital input of silicate minerals; a “semiclastic group” (Ti, Rb, Ba, P), which follows the clastic trend, but not quantitatively; and Mn, S, Sr (and Mg) which form the “diagenetic group” with special behaviour. The differences are: B.1) Cerin in general is purer than Eichstatt, but according to the correlation lines in 2-element-diagrams it has relatively less K and Al, more Si and Fe, and more Mg in the carbonate phase. B.2) For Eichstatt it can be suggested that the sediment was brought into the plattenkalk basin as a ready mixture of carbonate and non-carbonates. At Cerin the relation between thickness and contents of insolubles proves the “Seibold-rule”: dilution of insoluble input by in situ carbonate production. Cerin is a simple rhythmite, whereas Eichstatt is dominated by “undulations”. These features, and the differences described in B.2, are used as the basis for definition of “Plattenkalk C-type” and “E-type”.