Abstract The Anti-Atlas contains a thick, volcanic-free Ordovician succession that originally deposited in passive-margin basin. Three main sedimentary packages are bounded by major unconformities: (i) the Tremadocian–Floian Lower Fezouata and Upper formations, which unconformably overlie palaeorelief of Cambrian rifting volcanosedimentary complexes, subsequently topped Dapingian paraconformabl...

BACKGROUND During the Ordovician the global diversity increased dramatically at family, genus and species levels. Partially the diversification is explained by an increased nutrient, and phytoplankton availability in the open water. Cephalopods are among the top predators of today's open oceans. Their Ordovician occurrences, diversity evolution and abundance pattern potentially provides informa...

Magnetostratigraphic studies of the Ordovician provide evidence for nature core-mantle boundary interactions, and means dating correlation across differing environmental regimes. We new magnetostratigraphic data from Middle Upper Ordovician, compiling this into a polarity chronostratigraphic scale Dapingian to Hirnantian interval. The are derived Backside Beck Cheney Longville sections in Brita...

Two new mitrate stylophorans are described from the upper part of Santa Rosa Formation (Lochkovian) in Central Subandean Zone Bolivia and Jupiter (Cybèle Member, late Llandovery) Anticosti Island (Canada). Both identified as allanicytidiine anomalocystitids. The Bolivian mitrate, Perikefalea racheboeufi gen. sp. nov. is characterized by a strongly reduced number plates (five) on its thecal surf...

The excellent preservation of the acritarchs, their great abundance, diversity and good stratigraphic control permit establishment of a detailed Middle and Late Cambrian acritarch biozonation. A total of 56 palynomorph species form the basis of 10 local acritarch assemblage zones. Assemblage zones I-II occur in the lower and middle parts of the Member C of the Mila Formation and suggest Early-m...

Distinctive uppermost Ediacaran–Ordovician rocks (Avalonian overstep sequence) were key in definition of Avalonia, which comprises large areas the NE Appalachians and Caledonian Variscan mountains (Britain western Europe). This siliciclastic-dominated cover succession unconformably overlies a Neoproterozoic pre-Avalonian basement collage (arc, continental, oceanic fragments; Gwna-type melanges ...