Résumé: <em>Isastrea</em>, genre de scléractiniaire mésozoïque montre habituellement une forme massive et une structure coloniale cérioïde. Des échantillons provenant du Bajocien de Lorraine France démontrent pour la première fois que le polypier peut être branchu, phacéloïde. Cette structure est interprétée comme le résultat d'une mort partielle de la colonie.<br /> Abstract - <i>Isastrea</i>, a Mesozoïc genus of Scleractinia usually shows a massive form and a cerioid colonial structure. Samples from the Bajocian of Lorraine France demonstrate for the first time that the corallum may be branching and phaceloid. This structure is interpreted as the result of a partial death of the colony.
An incomplete chimaeroid (<em>Holocephali, Chimaeroidei</em>) mandibular dental plate from the early Bajocian (<em>Humphriesianum</em> Zone) of Ottange-Rumelange, on the Luxembourg-French border, is described as a new genus and species of callorhinchid fish <em>Ottangodus lotharingiae</em> gen. et sp. nov. Comparison of the described plate with other Jurassic chimaeriform fish (both myricanthid and chimaeroid) mandibular plates shows relationships with callorhinchids and in turn close relationships with the genus <em>Pachymylus Woodward</em>, known from the Callovian of England. The plate of the new genus shows a set of primitive characters for chimaeroids (very high descending lamina, low oral part of the plate, large centrally placed median tritor occupying most of the oral part of the plate and an absence of mesio-labial system of the tritors) and could thus belong to a basal <em>Chimaeroidei</em> taxon. This is the first record of the <em>Chimaeroidei</em> from the Jurassic of Lorraine and the fourth chimaeriform genus known from the Mesozoic of the region.
In this paper a new taxon of Kuehneotheriidae is described and diagnosed, mainly by comparison with the genus Kuehneotherium. By its greater age and its more primitive evolutionary state, Woutersia mirabilis gen. et sp. nov. is a particularly interesting element of the fauna and enlarges the concept of the Kuehneotheriidae.
Dans cet article est décrit et défini un nouveau taxon de Kuehneotheriidés, Woutersia mirabilis gen. et sp. nov., par comparaison avec Kuehneotherium. Son âge plus ancien et son stade d'évolution considéré comme plus primitif en font un élément particuliérement intéressant, qui élargit en outre le concept des Kuehneotheriidés.
The origin of perylene, a five-ring polycyclic aromatic hydrocarbon (PAH), in sediments has been a matter of constant debate and its formation mechanisms remain unclear. A perylene record in sediment was described and could support a clear link between perylene and terrigenous organic matter (OM) input. The distributions of PAHs, the variations of organic proxies such as the ratio of terrigenous to aquatic n-alkanes (TAR₍HC₎) and 5α(H)-stanols/Δ⁵-sterols ratio in sediments have been investigated. Sediments were sampled from a pond artificially created during the Middle Ages from a swampy area. In the period prior to the pond creation, for which high contributions of terrigenous OM were evidenced, perylene was found to be the predominant PAH. Furthermore, perylene content was shown to increase in response to the establishment of more reducing conditions. This result supports the common idea that the main source of perylene is natural and derives from biogenic precursors under reducing conditions. The creation of the pond in this wetland is marked by the deposition of a wood rich level characterized both by more oxygenated conditions and higher concentrations of perylene. These high concentrations could result from the introduction of high concentrations of biogenic precursors of perylene under oxidative conditions. Subsequently, the progressive burial of the woody level could have allowed the establishment of oxygen depleted conditions and the formation of perylene. These results validate the use of perylene as a paleoenvironmental marker of terrigenous sources but it must be carefully used as a marker for syn- or post-depositional oxygen depleted conditions in lacustrine environments.
