Abstract The Ordovician of North and West Africa comprises three main transgressive–regressive sequences understood as ‘second-order’ cycles of 10–15 myr duration. Tide- to wave-dominated shallow-marine clastic successions, preserving incidental bryozoan carbonates to the north, include fluvial deposits over the most proximal southern stretches of the platform. The boundary with Cambrian strata remains unclear but the latter are progressively less represented to the south in the undifferentiated ‘Cambro-Ordovician’. To the north, graptolites, brachiopods and trilobites combined with palynomorphs provide a robust biostratigraphic frame. Maximum flooding intervals occurred in the early to middle Tremadocian, middle Darriwilian and middle to late Katian. Two events interfered with an overall long-term transgressive trend. The ‘intra-Arenig’ (late Floian?) tectonic event highlighted palaeohighs coinciding with Paleoproterozoic basements. Gondwanan drainage basins were reorganized, which had an impact on sediment sourcing and distribution of detrital material (e.g. zircons) feeding the pre-Variscan Europe. The second event is the end-Ordovician glaciation. The domain supported the greatest part of the Hirnantian glaciers and may also have preserved pre-Hirnantian glacial archives. It is not until the very latest Ordovician that offshore conditions developed far inland; it is however suspected that this inundation benefited from a transient postglacial isostatic flexure.

Abstract The Ordovician documented in southeastern Europe reflects different sedimentary environments, from shallow water to basin, belonging to diverse palaeogeographical domains. Some of these geological sectors and their palaeontological content have been well described for a long time such as the Carnic Alps, which represent one of the most continuous Paleozoic sequences in the world. For some other areas, the quality of the data is variable and the knowledge is less detailed, sometimes with lithostratigraphic units still to be formalized, which also reflects the fragmentary nature of the outcrops. The Ordovician stratigraphy of southeastern Europe with its diverse successions has been revised herein and integrated with new data in an attempt to develop a global scenario for this critical time interval in the evolution of life.

Abstract The extensive, predominantly siliciclastic deposits of the Upper Ordovician of the Tafilalt have long been the subject of scientific investigation. In the past 25 years, intensified collecting for commercial purposes has resulted in the discovery of several exceptionally-preserved faunas (Konservat-Lagerstätten) in the Tafilalt region, preserving a range of non-biomineralized and soft-bodied organisms. The preservation of these fossils in the coarse clastic sediments of the Tafilalt is surprising, and in the case of soft-bodied organisms, remarkably similar to the preservational mode of typical Ediacaran biotas. These relatively recent discoveries have increased the scientific significance of the Tafilalt Biota, providing an unparalleled insight into the composition and temporal evolution of the shallow, open-marine ecosystems and their denizens during the later stages of the Great Ordovician Biodiversification Event. At least nine different phyla, in addition to several soft-bodied problematica are represented in the Tafilalt. While the highly diverse and remarkably well-preserved echinoderm and euarthropod faunas are most emblematic for the Tafilalt Biota, further studies have revealed a relatively high diversity of molluscs and brachiopods. Among soft-bodied fossils, the problematic paropsonemid eldonids are iconic for the Tafilalt and stand out both through their abundance, and their wide temporal and geographical range throughout the area.

Abstract The Anti-Atlas contains a thick, volcanic-free Ordovician succession that originally deposited in a passive-margin basin. Three main sedimentary packages are bounded by major unconformities: (i) the Tremadocian–Floian Lower Fezouata and Upper Fezouata formations, which unconformably overlie a palaeorelief of Cambrian rifting volcanosedimentary complexes, and are subsequently topped by a Dapingian paraconformable gap; (ii) the Darriwilian–Katian Tachilla Formation and First Bani and Ktaoua groups, the latter unconformably overlain by a Hirnantian glaciogenic succession; and (iii) the Second Bani Group, which subsequently infilled the former glaciogenic palaeorelief. Due to the scarcity of carbonate interbeds for etching analyses, leading to rare references of conodonts, the global Ordovician chart is interpolated on the basis of microphytoplancton (acritarchs and chitinozoans), regional graptolites and brachiopods. The Ordovician counter-clockwise rotation of Gondwana led its Moroccan margin from mid- to high-latitude positions, leading to the onset of a siliciclastic, wave- and storm-dominated platform. Flooding surfaces are marked by shelly silty carbonate interbeds that reflect the episodic development of echinoderm–bryozoan meadows during Katian times; in areas protected from siliciclastic input, they reached massive and bedded bioaccumulations (Khabt-el-Hajar Formation). The Hirnantian glaciation controlled the incision of numerous tunnel channels, infilled with both alluvial to fluvial sediments and glaciomarine diamictites. The Hirnantian palaeorelief was definitively sealed during Silurian times.

Abstract The fossil trade of Paleozoic material from southern Morocco was estimated by some North American media to reach about US$ 40 million a year, and it supplies fossil shows and shops all over the world. In its initial stages of extraction, preparation and export, this trade constitutes the main source of income to more than 50 000 people in an area basically conscribed within the triangle made by Alnif–Erfoud–Taouz (eastern Anti-Atlas), and generated a true ‘fossil industry’. This includes diggers and miners, artisans that prepare and restore fossils (and others dedicated to making replicas with decorative purposes), quarries working on fossiliferous ornamental rocks, and numerous middlemen and Moroccan wholesalers who annually attend the large fossil fairs of Europe and the USA. More than 25 years of intensive exploitation of fossil resources in the Anti-Atlas has also produced important scientific discoveries, such as world-renowned fossil biotas like Fezouata and Tafilalt, and hundreds of new Paleozoic fossil taxa, in parallel with a worrying destruction of outcrops and many palaeontological sites. The new mining legislation also deals with the extraction, collection and trade of geological specimens, and a future specific legal framework for fossils and geological heritage will try to manage the existing industry. It will aim to restrain the constant deterioration of the rich Moroccan geological heritage, while enabling strategies of sustainable development so that the local population is not negatively affected.

Abstract The early Late Ordovician (Sandbian 1) representatives of the Tafilalt Biota in the locality of Bou Nemrou (Jbel Tjarfaïouine) provide examples of fossil preservation in medium-grained sandstones with abundant microbially induced sedimentary structures. The recorded trilobite assemblage comprises 11 species of ten genera, among which one is new ( Placoparia africana Pereira & Gutiérrez-Marco, sp. nov.) and four others previously regarded as endemic to the locality are considered to be synonymys of species already described from Bohemia. The oldest representative of the illaenid genus Cekovia is recorded, revised diagnosis proposed for the genus Mytocephala Struve and for Uralichas tardus Vela & Corbacho. Parvilichas Corbacho & Vela is considered to be a junior synonym of Uralichas Delgado. From a palaeobiogeographical point of view, the Bou Nemrou locality shows strong relationships with trilobite assemblages from the Dobrotivian and with the lower Berounian sandstone facies of Bohemia, reinforcing the correlation of both regions. Some soft-bodied structures are recognized here, including the digestive tracts of Uralichas and the traces of paired, metameric axial bands in the anterior thoracic segments of the trilobite Selenopeltis preserved in apatite and interpreted as intersegmental musculature.

Abstract Storm-dominated siliciclastic shelf deposits in the upper half of the Upper Tiouririne Formation (Upper Ordovician, upper Berounian– c. Katian 1–2) of southern Morocco contain large specimens of at least two species of Archaeoconularia ( A . aff. consobrina and A . cf. imperialis ). Pseudoconularia cf. grandissima occurs in basal beds of the formation, but is far less abundant than Archaeoconularia . The large size of the Archaeoconularia (>500 mm long in some cases) suggests gigantism induced by cold, nutrient-rich waters. Specimens preserving the apical end terminate in a schott, indicating that the conulariids were severed near the apex prior to final burial. Many of the Archaeoconularia occur in monospecific aggregations in which the component specimens exhibit preferential alignment, probably owing to entrainment and burial by storm currents or flows. Some Archaeoconularia are encrusted by edrioasteroids and/or craniid brachiopods, which in certain cases are so closely spaced as to interfere with growth. The edrioasteroids and brachiopods were probably epibionts attached to living, erect or semi-erect conulariids that were partially infaunal. More generally, Late Ordovician conulariid assemblages of South Polar Gondwana and adjacent terranes exhibit low generic diversity relative to those of low- to mid-latitude terranes (Baltica and Laurentia), and are dominated numerically by Archaeoconularia .

Abstract Upper Ordovician planktic and benthic graptolites are generally rare in North Africa. Four localities in southern Morocco have yielded graptolitic material from the top of the First Bani Group and the Lower Ktaoua, Upper Tiouririne and Upper Ktaoua formations, the lithostratigraphic units that contain the Tafilalt Biota. Three species of planktic graptolite (in the genera Climacograptus , Diplograptus ? and Neodiplograptus ), six species of benthic graptolite (in the genera Dendrograptus , Callograptus , Ptilograptus and ‘ Dictyonema ’) and one probable hydroid ( Webbyites ? sp.) are described from these sites. Two species are new: ‘ Dictyonema ’ khadijae sp. nov. and ‘ Dictyonema ’ villasi sp. nov. Another probable hydroid, a Plumalina -like form from the Lower Ordovician Fezouata Formation, is also illustrated. Some of the Tafilalt graptolites are similar to Bohemian species, indicating faunal links between the regions during the Late Ordovician. The graptolite dating of some isolated localities helps to evaluate the chronostratigraphic and lithostratigraphic assignment of those outcrops, implying an earlier appearance of the ‘ Dendrocystites fauna’ (echinoderm-dominated: c. Sandbian 2–Katian 1) and a late placement for the ‘ Declivolithus fauna’ (trilobite-dominated: c. Katian 2).

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.

Abstract Cornute stylophorans are a minor, although typical, component of Middle–Late Ordovician echinoderm assemblages adapted to soft siliciclastic substrates in high-latitude peri-Gondwanan regions. All previously reported occurrences of Darriwilian–Katian cornutes from the Czech Republic, France, Morocco and Spain are revised and their plate homologies reassessed. The genera Beryllia and Juliaecarpus are reinterpreted as junior synonyms of Domfrontia , and Thoralicystis is synonymized with Bohemiaecystis . Several Mediterranean scotiaecystids previously assigned to Bohemiaecystis and/or Scotiaecystis are placed within Thoralicarpus gen. nov., and cornute taxa originally left in open nomenclature by Chauvel are formally described as Bohemiaecystis chouberti sp. nov. (AVI) and Destombesicarpus izegguirenensis gen. et sp. nov. (AVIII). Other new Mediterranean taxa include Arauricystis clariondi sp. nov., Destombesicarpus budili gen. et sp. nov., Milonicystis reboulorum sp. nov., Thoralicarpus bounemrouensis gen. et sp. nov., and T . prokopi gen. et sp. nov. The six cornute genera identified in Darriwilian–Katian Moroccan echinoderm Lagerstätten are also present in coeval assemblages of at least one other Mediterranean region, thus supporting the existence of strong faunal affinities between the Anti-Atlas, the Armorican Massif, the Barrandian area and the Iberian Peninsula.

Abstract New Upper Ordovician Echinoderm–Lagerstätten from the Anti-Atlas of Morocco have provided large collections of blastozoan echinoderms. The echinosphaeritid Echinosphaerites dianae n. sp. preserves the oral region, stem and brachioles, characteristics absent in many species of the same genus. Homocystites adidiensis n. sp. is represented by almost 50 specimens that provide details on the growth in this taxon. This is the only species of Homocystites with granules in the external ridge of the outer proximal stem columnals. The genus Rhombifera is recognized for the first time in Morocco based on one partially preserved thecal plate. Assemblages are characterized by low diversity of rhombiferan blastozoan echinoderms that provide further palaeogeographical links at genus level with Gondwana, Baltica and Avalonia.

Abstract The Iberian Peninsula comprises the most extensive outcrops of Ordovician rocks in Europe. They are mainly situated within the different ‘zones’ of the Variscan Iberian Massif (also referred to as the Hesperian Massif), except the South Portuguese Zone, as well as in the Palaeozoic massifs of the Iberian Cordillera (an isolated part of the Iberian Massif), the Catalonian Coastal Ranges, the Pyrenees and the Betic Cordillera (Fig. 4.1 ). Geological sketch map of the Iberian Peninsula showing the distribution of Ordovician rocks (in black) with reference to the main Precambrian and Palaeozoic exposures (stippled). Key: A–G, Hesperian (Iberian) Massif: A, Cantabrian Zone; B, West Asturian-Leonese Zone; C, Iberian Cordillera; D, Galicia–Trás-os-Montes Zone; E, Central Iberian Zone; F, Ossa Morena Zone; G, South Portuguese Zone (dotted lines indicate zone boundaries); H, Betic Cordilleras; I, Catalonian Coastal Ranges; J, Pyrenees. 1–42, Main Ordovician reference sections and fossil localities in Spain: 1, Cabo Peñas; 2, ‘folds and nappes region’; 3, Sueve area; 4, Rececende and Villaodrid synclines (Mondoñedo Nappe); 5, Los Oscos thrust-sheet; 6, Vega de Espinareda synclinorium; 7, Caurel–Peñalba syncline; 8, Castrillo syncline; 9, Eastern Iberian Chains; 10, Albarracín anticlinorium (Western Iberian Cordillera); 11, Serranía de Cuenca anticlinorium; 12, Cabo Ortegal area; 13, Sil and Truchas synclines; 14, Alcañices synclinorium; 15, Guadarrama area (eastern ‘Central System’); 16, Verín-Bragança region; 17, Tamames syncline; 18, Sierra de San Pedro and Cáceres syncline; 19, Cañaveral-Monfragüe syncline; 20, Guadarranque syncline; 21, Herrera del Duque syncline; 22, Corral de Calatrava syncline; 23, Almadén syncline; 24, Torre