During the late middle Oxfordian, patch reefs grew on the northern margin of the Paris Basin. According to the facies analysis of the reef and inter-reef sediments, the environment was a warm, clear and agitated sea with highly episodic sedimentation. The bioherms were a short-lived phenomenon during the third phase of regional reefal development. Sequence stratigraphically, they are associated with a highstand system tract. Volumetrically and trophically dominant organisms were microbes now represented by massive clotted leiolite; ‘stalactitic’ hemispheroids with purely thrombolitic texture are restricted to open caves. <br /><br />Corals were of structural, reef-building importance due to their rapid upward growth. The patch reefs are characterised by thickets of ramose corals which developed a very open framework. In the vicinity of these patch reefs, though in hydrodynamically higher-energy environments, grew thickets of more stoutly branched corals; however, they are rarely preserved in situ and are generally represented as abundant coral rubble. The reef taxa are characterised by the notable absence of several groups (e.g. oysters, serpulids, bryozoans, pectinids) occurring at other localities where reefs of similar age developed in similar environmental conditions. The reefs also have strikingly modern aspects to them, in particular the presence of cryptic elements within caves and a sponge-dominated borer association. Dwellers belong to various life-form types although encrusting taxa are exceedingly rare. This may be explained by the presence of soft microbial films on most surfaces. <br /><br />The palaeoecological analysis suggests that the major controls on faunal composition and high diversity were elevated nutrient levels, highly episodic sedimentation and probably seasonal environmental disturbances. Structural and functional aspects of the reef community (grazers trigger framebuilders, borers trigger binders, binders hamper borers) allow ecological comparisons to be made with contemporaneous, as well as Recent, reefs. The unique combination of ecological factors resulted in a specialised, previously undescribed, community which differs from both Tethyan and northern localities in various aspects; these include cavities with cryptofauna, prominence of grazing gastropods and high faunal diversity in a microbially dominated build-up.
The late Variscan evolution of the Saar-Nahe Basin in southwest Germany is closely controlled by the kinematics of the Hunsrück Boundary Fault, which also separates two main tectonostratigraphic units of the Variscides. The Saar-Nahe Basin comprises a half-graben structure, which formed due to extensional reactivation of a Variscan thrust. Between the early Westphalian and late Rotliegend, about 8.5 km of alluvial fan, fluvial and lacustrine sediments accumulated. During the Permo-Carboniferous, W-E oriented extension was accommodated by a system of NW-SE trending transfer faults and orthogonal normal faults. Balanced cross-section construction and subsidence analyses suggest a 35% extension of the previously thickened crust in the late stage of the orogeny. The subsidence analyses show discontinuous depth-dependent extension, with laterally varying extension factors in the crust and mantle. The offset between syn- and post-rift depocentres is explained by a mantle stretching zone, shifted laterally with respect to the area of maximum crustal extension. Finally, a geodynamic model for the evolution of the Saar-Nahe Basin, with special reference to the earlier Variscan development and the general evolution of Permo-Carboniferous basins in Central Europe is presented.
Numerous isolated cynodont teeth have been collected from the Late Triassic of Saint-Nicolas-de-Port (north-eastern France). The material is very diversified and the following taxa are recognized: <em>Pseudotriconodon wildi</em> Hahn, Lepage et Wouters, 1984, <em>Tricuspes tuebingensis</em> E. v. Huene, 1933; <em>Tricuspes sigogneauae</em> Hahn, Hahn et Godefroit, 1994; <em>Tricuspes tapeinodon</em> n.sp.; <em>Meurthodon gallicus</em> Sigogneau-Russell et Hahn, 1994; <em>Hahnia obliqua</em> n.g., n.sp.; <em>Gaumia longiradicata</em> Hahn, Wild et Wouters, 1987; <em>Lepagia gaumensis</em>, Hahn, Wild et Wouters, 1987; <em>Maubeugia lotharingica</em> n.g., n.sp.; <em>Rosieria delsatei</em> n.g., n.sp. and aff. Microscalenodon. This cynodont fauna mainly includes small insectivorous forms, more particularly represented by Dromatheriidae; tiny herbivorous are represented by rare dwarf Traversodontidae. The study of the palaeogeographical and stratigraphic distribution of the Late Triassic to Early Jurassic cynodonts indicates that the fauna discovered in Saint-Nicolas-de-Port is characteristic of the Late Norian-Rhaetian period and is actually the most representative of this period for Western Europe. Granulomatric analysis of the bone-bed reveals that they accumulated in a nearshore shallow marine environment.
