Abstract A review of the literature shows that the Famennian global Annulata Event(s) can be recognized as a transgressive, often hypoxic and eutrophic, interval that interrupts an overall regressive eustatic trend in more than 40 regions of North America, Europe, North Africa, Asia and Australia. According to differences in palaeogeography, sedimentology and biota, these occurrences are assigned to 10 event settings. The first detailed data on facies, ammonoid and conodont faunas are presented for the Rheris Basin of the eastern Anti-Atlas (southern Morocco) and compared with previously studied sections of the adjacent Tafilalt Platform, Tafilalt Basin and Maider Basin. The rather argillaceous succession at El Gara resembles the Tafilalt Basin (Hassi Nebech section) in its lack of black shales/limestones and similar ammonoid and conodont assemblages. However, the Sulcoclymenia sulcata Zone (Upper Devonian III-C2) below the Annulata Events contains ammonoid taxa that are unique for all of the Anti-Atlas and North Africa: Protornoceras ornatum Dybczynski, 1913 , Genuclymenia aff. angelini ( Wedekind, 1908 ), Protactoclymenia aff. implana ( Czarnocki, 1989 ) and ? Pleuroclymenia sp. juv. The first regional record of the marker conodont Pseudopolygnathus granulosus Ziegler, 1962 also distinguishes the pre-event assemblage. As in many other regions, there is a major decline in ammonoids well before the Lower Annulata Event, which suggests an episode of extreme oligotrophy. Both Annulata Events at El Gara are whitish-weathered marly shales with only small specimens of Platyclymenia and Prionoceras ( sensu lato ), which are also typical for the annulata Zone (UD IV-A) of other Tafilalt sections, but benthonic organisms are nearly absent. This suggests local low-oxygen conditions, but only a moderate production of organic carbon, insufficient for black shale formation, unlike many German sections or in the Maider Basin (section Mrakib). The latter region represents a deeper shelf basin that had much higher productivity and a unique ‘ Gundolficeras – Erfoudites – Protactoclymenia – Stenoclymenia – Guerichia biofacies’ of the Lower Annulata Shale. The upper part of the annulata Zone at El Gara is characterized by Platyclymenia ( Platyclymenia ) levata n. sp. Other new taxa of the same zone in the Anti-Atlas are Posttornoceras ascendens n. sp. and Stenoclymenia rectangula n. sp. Whilst the ammonoid faunal overturn between UD III-C and UD IV-A was severe, the strong reduction in conodont diversity with the two Annulata Events was mostly (apart from two taxa) a palaeoecologically triggered, only episodic, feature. The comparison of the various Anti-Atlas Annulata Event beds and assemblages enables the distinction of event biofacies types, which reflect local differences of bathymetry, trophic conditions and seafloor ventilation.

Abstract In Belgium, the Lower Kellwasser Event (LKW) corresponds to the relative sea-level maximum of the first (‘Aisemont sequence’ (AS)) of the two late Frasnian third-order sequences that are recognized here, but the Upper Kellwasser Event (UKW) may have been triggered by a series of tsunamites. The end of the middle Frasnian carbonate platform and reefs is caused by the sea-level drop and emersion of the last middle Frasnian third-order sequence (‘Lion sequence’) in the Lower rhenana Zone. The end of the ‘Petit-Mont’ mudmound growth during the transgressive (TST) and highstand (HST) systems tracts of the AS was caused by sea-level fall and emersion at the top of this sequence. The coral and brachiopod extinction in the Upper rhenana Zone, during the second late Frasnian third-order sequence (‘Lambermont sequence’ (LS)), is progressive and due to the widespread development of the dysoxic and anoxic facies, before the UKW. Only the LS TST has been identified. No sea-level fall has been recognized in relation to the UKW or near the Frasnian–Famennian boundary. The late Frasnian extinctions are more likely to be related to the decrease in the atmospheric oxygen rate and its impact on marine environments and, to complete, the UKW.

Abstract The global Hangenberg Crisis near the Devonian–Carboniferous boundary (DCB) represents a mass extinction that is of the same scale as the so-called ‘Big Five’ first-order Phanerozoic events. It played an important role in the evolution of many faunal groups and destroyed complete ecosystems but affected marine and terrestrial environments at slightly different times within a short time span of c. 100–300 kyr. The lower crisis interval in the uppermost Famennian started as a prelude with a minor eustatic sea-level fall, followed rather abruptly by pantropically widespread black shale deposition (Hangenberg Black Shale and equivalents). This transgressive and hypoxic/anoxic phase coincided with a global carbonate crisis and perturbation of the global carbon cycle as evidenced by a distinctive positive carbon isotope excursion, probably as a consequence of climate/salinity-driven oceanic overturns and outer-shelf eutrophication. It is the main extinction level for marine biota, especially for ammonoids, trilobites, conodonts, stromatoporoids, corals, some sharks, and deeper-water ostracodes, but probably also for placoderms, chitinozoans and early tetrapods. Extinction rates were lower for brachiopods, neritic ostracodes, bryozoans and echinoderms. Extinction patterns were similar in widely separate basins of the western and eastern Prototethys, while a contemporaneous marine macrofauna record from high latitudes is missing altogether. The middle crisis interval is characterized by a gradual but major eustatic sea-level fall, probably in the scale of more than 100 m, that caused the progradation of shallow-water siliciclastics (Hangenberg Sandstone and equivalents) and produced widespread unconformities due to reworking and non-deposition. The glacio-eustatic origin of this global regression is proven by miospore correlation with widespread diamictites of South America and South and North Africa, and by the evidence for significant tropical mountain glaciers in eastern North America. This isolated and short-lived plunge from global greenhouse into icehouse conditions may follow the significant drawdown of atmospheric CO 2 levels due to the prior massive burial of organic carbon during the global deposition of black shales. Increased carbon recycling by intensified terrestrial erosion in combination with the arrested burial of carbonates may have led to a gradual rise of CO 2 levels, re-warming, and a parallel increase in the influx of land-derived nutrients. The upper crisis interval in the uppermost Famennian is characterized by initial post-glacial transgression and a second global carbon isotope spike, as well as by opportunistic faunal blooms and the early re-radiation of several fossil groups. Minor reworking events and unconformities give evidence for continuing smaller-scale oscillations of sea-level and palaeoclimate. These may explain the terrestrial floral change near the Famennian–Tournaisian boundary and contemporaneous, evolutionarily highly significant extinctions of survivors of the main crisis. Still poorly understood small-scale events wiped out the last clymeniid ammonoids, phacopid trilobites, placoderms and some widespread brachiopod and foraminiferan groups. The post-crisis interval in the lower Tournaisian is marked by continuing eustatic rise (e.g. flooding of the Old Red Continent), and significant radiations in a renewed greenhouse time. But the recovery had not yet reached the pre-crisis level when it was suddenly interrupted by the global, second-order Lower Alum Shale Event at the base of the middle Tournaisian.

Abstract The Silurian-Devonian (mid-Paleozoic), a time of periodic, exceptional sea level highstands, vast epicontinental sea lanes, and global greenhouse climates well above Holocene norms, also identifies ihe ma ximal extent of Phanerozoic metazoan reef development and the acme of coral and sponge reef biodiversity Two peaks are identified for reef distribution, a mid-Silurian (Wenlock) maximum and a Mid- to Late Devonian (Eifel-Givet-middle Frasne) maximum, with reefs spread to latitudes as high as 45 lo 60 degrees, and major barrier-platform tropical reef belts stretched over more than 2000 km. Reef abundance broadly matched patterns of rise and fall in generic biodiversity for (he major cneiazoan reef builders (corals and stromatoporoids) and algae during this 80 million year episode. The mid-Paleosoic reef community originated in the Late Ordovician, taking over from the Cambro-Ordovician mud mound-dominated reef spectrum. It was only modestly affected by the glaciation-induced end-Ordovician(Hirnantian) mass extinction events Late Devonian reef extinction losses were initiated al the Givetian-Frasnian boundary by major declines in coral, stromatoporoid, and brachiopod bentliic components Reefs then experienced a second global expansion in the middle Frasnian, but with reduced faunal diversity. Catastrophic reef declines began in the late Frasnian rhenana conodont Zone and continued through the final lingurformis Zone, with events probably lasting ca.l Myr.Thecorat-stromatopofoid reef community was eliminated worldwide, with surviving patch reefs and reefalrnud mounds in ihe Famennian constructed by consortia of catcimicrobes, lifhisrid sponges, green and red algae, and foraminiferans. The surviving Famennian corals were primarily solitary, deep-water forms that played no major reef role. The last stramatoporoids died out within the Strunian praesuicata Zone, at the Devonian -Carboniferous boundary Widespread organic-rich carbonates of Civetian through Famennian age, normally taken as indicative of anoxia, do not show any correlation with local or global reef declines The Frasnian-Famennian extinction events foi reefs and reef faunas appear to have been second only to the end-Permian reef losses in terms of severity Metazoan reef extinction in the Late Devonian best parallels evidence for Famennian glaciarions, loss of reef accommodation space assealevels fell, 3nd increasing oxygenation of the atmosphere via the evolution of the first pteridophyte rainforests, forcing the terminal Famennian icehouse phases