Abstract >The Early Palaeozoic history of England and Wales was substantially influenced by the separation of Avalonia from Gondwana and its subsequent migration towards Laurentia. At the start of the Early Palaeozoic, the vast palaeocontinent of Gondwana straddled the South Pole and extended northwards into low latitudes. On the margin that hosted North Africa and North and South America there were areas of crust that were later to become detached terranes. The largest of these was Avalonia, the remnants of which now extend from NE USA, through the Atlantic Provinces of Canada and through England and Wales to Belgium and North Germany ( Cocks 2000 ). Elsewhere, at lower latitudes on the Gondwana margin, there were crustal segments that were later to become the terranes of Armorica (Britanny, Normandy and the Massif Central regions of France), Perunica (much of central Europe, but mainly preserved in the Bohemian part of the Czech Republic) and Iberia (Spain). In addition there are some smaller continental fragments whose history is difficult to establish. The area of England and Wales lay within Eastern Avalonia, which consisted of an initial crustal fragment that separated from Gondwana ( Fig. 3.1a ) and then accreted smaller terranes as it moved towards Laurentia. The core Avalon Terrane was probably assembled by accretion of crustal fragments on the Gondwana margin in the Late Precambrian or early Cambrian. At about the same time, this terrane accreted both the basement of the Welsh Basin ( Woodcock & Gibbons 1988 ) and an amalgamation

Abstract More than 30 species of tergomyan, gastropod, bivalve and cephalopod molluscs are described from the Late Ordovician of central and eastern Anti-Atlas, Morocco. For the cephalopods this represents the first systematically known taxa of the region. Tergomyans and gastropods are most common in the more shaly part of the Lower Ktaoua Formation, while bivalves are more frequent in the sandy part of the Lower Second Bani Formation. A southern Gondwana aspect is evident for the tergomyan, gastropod and bivalve assemblages, sharing many taxa with Bohemia, while no clear signal is present for the cephalopods. The latter reflects insufficient knowledge of the fauna of large parts of these areas. The widely recognized Holopea ? antiquata is transferred to the genus Radvanospira gen. nov.; other new gastropod taxa include Allossospira gen. nov., Tritonophon grandis sp. nov., Radvanospira baniensis sp. nov. and Lophospira latilabra sp. nov. Most of the diverse bivalve fauna and the few cephalopods are left in open nomenclature but new taxa include the bivalve Praenucula pojetai sp. nov. and the cephalopods Wadema tattai sp. nov. and Tafadnatoceras tiouririnense gen. et. sp. nov. The Late Ordovician bivalves from Morocco are dominated by pteriomorphs and protobranchs, inhabiting infaunal, semi-infaunal and epifaunal niches.