CONODONT BASED TRILOBITE BIOZONATION IN THE LATE DEVONIAN OFF-SHORE REALM

The thirteen-fold Montagne Noire conodont zonation is a world-wide standard for correlation and fine-scaled subdivision of the Late Devonian Frasnian stage. The stratotypic sections of this zonation in the south-eastern Montagne Noire (southern France) were investigated for trilobite communities. A succession of 10 trilobite assemblages recognized between the Late Givetian through the Frasnian-Famennian boundary can be integrated into the conodont zones. The first proposed trilobite assemblage-zones in the Late Devonian are mainly based on the following three independent phyletic lines each characterized by evolutionary trends towards eye-reduction: i. Longicoryphe-Pterocoryphe-Pteroparia lineage (Tropidocoryphidae), ii. Palpebralia palpebralis-P. brecciae lineage (Proetidae) and iii. Acuticryphops morphotypic line (Phacopidae). The palaeogeographic extension of some of these trilobite assemblages from Montagne Noire and Morocco (North Gondwana margin) to NW Australia (NE Gondwana), Thuringia (Armorican Assemblage) and to the Rhenan region of North-Central Europe (Avalonian margin of Laurussia) demonstrate their importance for possible international correlations of outer shelf areas in the early Late Devonian.