Bernard Mottequin

Kellwasser horizons, sea-level changes and brachiopod–coral crises during the late Frasnian in the Namur–Dinant Basin (southern Belgium): a synopsis

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.

Late Middle Frasnian to Early Famennian (Late Devonian) Strophomenid, Orthotetid, and Athyridid Brachiopods from Southern Belgium

Abstract Brachiopods of the orders Strophomenida, Orthotetida, and Athyridida from the late middle Frasnian–early Famennian interval (hassi to triangularis conodont zones) in the Namur-Dinant Basin (southeastern margin of Laurussia; southern Belgium) are described. Nine genera and subgenera represented by 12 species are recognized here. One new genus, Retrorstrophia, and one new species, Douvillina area, are erected. Crinisarina stainbrooki is proposed to solve the homonymy between C. reticulata (Gosselet, 1877) and Cleiothyridina reticulata Stainbrook, 1947, the type species of Crinisarina Cooper and Dutro, 1982. A lectotype is selected and illustrated for C. reticulata. A new name is also proposed for Athyris reticulata Chen and Xu, 2000, which is assigned here to Crinisarina: C. shashishanensis nom. nov. In southern Belgium, the last representatives of the families Douvillinidae and Leptostrophiidae (Strophomenida) are from the Upper rhenana Zone (late Frasnian). Athyridid brachiopods, especially the representatives of the subfamily Cleiothyridininae constituted a significant part of the early Famennian recovery faunas with spiriferids and rhynchonellids, just after the late Frasnian mass extinction.

Biostratigraphic significance of brachiopods near the Devonian–Carboniferous boundary

The biostratigraphic significance of selected uppermost Famennian (Upper Devonian) and lower Tournaisian (Mississippian) brachiopod genera, belonging to the orders Rhynchonellida (e.g. Araratella ), Spiriferida (e.g. Sphenospira , Prospira ), Spiriferinida ( Syringothyris ) and Productida (except Chonetidina), is discussed. Owing to the difficulties of identifying productidine and strophalosiidine genera, in contrast to rhynchonellides and spiriferides, the biostratigraphic potential of the former has generally been overlooked. Brachiopods flourished in neritic environments that were unfavourable for conodonts and ammonoids. In the absence of the latter traditional marker fossils, they are potentially important for locating the Devonian–Carboniferous boundary in shallow water depositional settings in conjunction with rugose corals and foraminifers. On a worldwide scale, further work is required to reach a better assessment of the aftermath of the Hangenberg biological Crisis on brachiopods, notably in revising the faunas from the classical areas of the Famennian and Tournaisian stages in Western Europe.

Famennian rhynchonellides (Brachiopoda) from deep-water facies of the Ougarta Basin (Saoura Valley, Algeria)

In the Saoura Valley (Ougarta Basin, Saharan Algeria), the lower–upper Famennian part of the essentially shally Marhouma Formation is characterized by deep-water facies and includes horizons rich in ammonoids (goniatites and clymeniids) and blind to eye-reduced phacopide trilobites. They are also rich in small-sized and smooth rhynchonellide brachiopods, investigated here for the first time in order to detail their post-Kellwasser recovery. Rhynchonellides clearly predominate in the brachiopod assemblages (representing 90% of the whole assemblage, with 10 species) composed otherwise of athyridides, orthides and spiriferides. Rhynchonellides are mostly represented by relatively flat leiorhynchids and rozmanariids consistent with poor oxygenation on the sea floor. One new species is described ( Evanidisinurostrum saouraense sp. nov.); four genera, previously known only from the south-eastern margin of Laurussia, are reported for the first time from the northern margin of Gondwana: the leiorhynchid Sphaeridiorhynchus and the rozmanariids Leptoterorhynchus, Pugnaria and Novaplatirostrum .

New data on the incertae sedis biota and foraminifera of the mid-Famennian Baelen Member (Late Devonian, eastern Belgium)

The Baelen mud mounds in eastern Belgium represent a local member of the mid-Famennian Souverain-Pré Formation (an important carbonate interval within the Condroz Sandstone Group). The lower part of this member contains silty bioclastic wackestones and packstones that are particularly rich in the problematical protists Serrisinella and Dreesenulella. Plurilocular foraminifera (Septabrunsiina and Baelenia) and rare solitary rugose corals (Neaxon? sp.) occur within crinoidal grainstones (tempestites) interfingering with the latter bioclastic wacke-/packstones and with red-stained stromatactoid spiculitic mudstones (carbonate mud mound core facies). Although Serrisinella is quite common in other mid-Famennian limestones of Belgium, Dreesenulella is almost endemic of the Baelen Member. Both genera apparently inhabited the muddy sediment-water interface, constituting meadows probably in zones of intermittently strong bottom currents. The taxonomic similarities between Dreesenulella and Saccamminopsis are discussed, as well as their possible affinities with the Xenophyophora and Kokomiacea. The first stages of the Septabrunsiina–Baelenia foraminiferal lineage are analysed in detail. The taxonomic and palaeoecological positioning of Serrisinella and Dreesenulella adds to the discussion about the palaeobathymetry of the Baelen mud mounds and corroborates sedimentological evidence for their relatively shallow carbonate ramp depositional setting.

Increasing knowledge on biodiversity patterns and climate changes in Earth’s history by international cooperation: introduction to the proceedings IGCP 596/SDS Meeting Brussels (2015)

Current and future climate change is a global issue that can be addressed only by international cooperation. Climate modelling is a useful tool for a better understanding of climatological processes but is significantly enhanced by the knowledge of organisms and changing biodiversity in deep time. The midPalaeozoic was a time of rapid, fundamental change in Earth’s climate systems resulting in significant sea-level fluctuations and catastrophic changes in ocean chemistry producing global oceanic anoxia. Ecosystems were severely impacted by a series of mass extinctions and ecological perturbations (e.g. virtual loss of reef ecosystems) that fundamentally changed the trajectory of life on Earth. Fluctuations in the physical environment during these biotic crises are usually (but not always) revealed in the sedimentary record as black shales and as geochemical excursions in Devonian sediments. Regardless of methodology, all the analyses conclude that the midPalaeozoic was a time of multiple anoxic events and associated biotic crises that spanned many millions of years. Thus, an understanding of the major abiotic and biotic factors that shaped our planet and its ecosystems in the past is essential to the understanding of natural processes and the effects of human-induced global change at present and for forecasting possible future developments. In other words, knowledge on past systems is essential if we want to model future climate with confidence. Furthermore, it seems important to increase knowledge in areas and countries which are underrepresented in terms of climate change and event research in the midPalaeozoic. In that respect, IGCP projects, supported by IUGS and UNESCO, serve as door-opener in many countries. In the framework of the IGCP 596, we visited many countries in several continents. Fieldwork was often difficult and a real challenge (Figs. 1 and 2). Regardless of methodology such as geochemistry, geophysics or facies analysis, the detailed knowledge of fossils is crucial. Thus, alpha taxonomy remains the fundamental basis for any investigation of the evolution of life on Earth, including fields of phylogenetic analysis, historical biodiversity, biogeography and biostratigraphy. Today, there is a lack of awareness of the fundamental importance of systematics and/or biostratigraphy. Taxonomy is crucial to high-resolution biostratigraphy. The ongoing decline in research and expertise in that special field in palaeontology jeopardises future macroevolutionary and biostratigraphic studies. Thus the collabora t ion between IGCP 596 and the in terna t ional Subcommission on Devonian Stratigraphy (SDS) also tried to involve specialists working on different fossil groups to the extent possible. In that sense, many progress reports related to the revision and erection of new taxa were linked with the Palaeobiology Database (http://paleodb.org/). This article is a contribution to the special issue ‘Climate change and biodiversity patterns in the mid-Palaeozoic’

A reappraisal of the genus Tethyrhynchia Logan, 1994 (Rhynchonellida, Brachiopoda): a conflict between phylogenies obtained from morphological characters and molecular data

The genus Tethyrhynchia Logan in Logan Zibrowius, 1994 is revised on the basis of different methods of analysis including SEM observations, detailed ontogenetic study of the crural development, transverse serial sections, and shell microstructure. Some morphological characters cited in the original diagnosis are analysed and contested by the ontogenetic results. The type of crura of Tethyrhynchia, often placed in the arcual group, appears to be of the raducal group, instead. Paedomorphosis and heterochronic development offer the possibility of opening a dialogue between morphological and phylogenetic approaches to classification of rhynchonellide brachiopods.

Extreme reduction of morphological characters: a type of brachidial development found in several Late Cretaceous and Recent brachiopod species—new relationships between taxa previously listed as incertae sedis

Size reduction and development of a simplified brachidial structure occurred several times during the long evolution of the Phylum Brachiopoda. Even Recent forms may be micromorphic and paedomorphic with reduced brachidia or none at all. A revision of the Maastrichtian (Late Cretaceous) Terebratella (Morrisia?) suessi Bosquet, 1859 has allowed us to erect a new genus, Jagtithyris gen. nov., because its singular brachidium development does not match any platidiid structure. Such a brachidium has also been observed in another European Late Cretaceous brachiopod, which indicates that this type was not a unique morphological curiosity. This species is the micromorphic Campanian-Maastrichtian Leptothyrellopsis polonicus Bitner Pisera, 1979, which has brachidial structures in common with Jagtithyris suessi comb. nov., although a number of differences have been observed. The genera Leptothyrellopsis and Jagtithyris gen. nov., are included in a new family, Jagtithyrididae fam. nov. During an ongoing revision of extant brachiopod faunas we have been led to recognize a link between this family and representatives of the genus Simplicithyris Zezina, 1976. The taxonomic position of this peculiar group is also discussed.

Late Devonian (Frasnian) phyllopod and phyllocarid crustacean shields from Belgium reinterpreted as ammonoid anaptychi

The taxonomic affinities of fossils from the Frasnian succession of Belgium previously described as phyllopod and phyllocarid crustacean shields are discussed. The rediscovery of the holotype of Ellipsocaris dewalquei, the type species of the genus Ellipsocaris Woodward in Dewalque, 1882, allows to end the discussion on the taxonomic assignation of the genus Ellipsocaris. It is removed from the phyllopod crustaceans as interpreted originally and considered here as an ammonoid anaptychus. Furthermore, it is considered to be a junior synonym of the genus Sidetes Giebel, 1847. Similarly, Van Straelen’s (1933) lower to middle Frasnian record Spathiocaris chagrinensis Ruedemann, 1916, is also an ammonoid anaptychus. Although ammonoids can be relatively frequent in some Frasnian horizons of Belgium, anaptychi remain particularly scarce and the attribution to the present material to peculiar ammonoid species is not possible.

New insights on Tournaisian–Visean (Carboniferous, Mississippian) athyridide, orthotetide, rhynchonellide, and strophomenide brachiopods from southern Belgium

Twelve selected Carboniferous species belonging to seven genera of the orders Athyridida, Orthotetida, Rhynchonellida, and Strophomenida (Brachiopoda) from southern Belgium are revised and/or discussed, and sometimes photographed for the first time since their first description dating back to the 19th century. The investigated material originates from the historical type areas of the Tournaisian and Visean stages (Tournai and Visé, respectively) and from the Waulsortian carbonate buildups developed in the Namur–Dinant Basin. Two species are new (Leptagonia franca sp. nov., Serratocrista scaldisensis sp. nov.), and a new name is proposed (Nucleospira hannoniae nom. nov.) to solve the primary homonymy between Athyris globulina de Koninck and A. globulina Waagen. Taxonomic discussion involves selection of the holotype of Retzia intermedia de Koninck (definitely not an athyridide) and of lectotypes for several species of athyridides (Athyris globulina de Koninck, A. vittata de Koninck, and Retzia davidsoni de Koninck), and strophomenides (Orthis cylindrica M’Coy, Schellwienella radialiformis Demanet, and S. ornata Demanet). The palaeoecology of the investigated species and their biotic interactions with other organisms (e.g., drill holes, epizoans) are described. The analysis of the published data on the athyridides, orthotetides, and strophomenides occurring in southern Belgium during the Devonian–Mississippian reveals that our knowledge of these suspension-feeders in this part of the southern margin of Laurussia is currently insufficient to assess the aftermath of the different biological crises that took place during this time span, notably the Hangenberg Crisis at the end of the Famennian. Bernard Mottequin. Royal Belgian Institute of Natural Sciences, Operational Directorate Earth and History of Life, rue Vautier 29, B 1000 Brussels, Belgium. bmottequin@naturalsciences.be Eric Simon. Royal Belgian Institute of Natural Sciences, Operational Directorate Earth and History of Life, rue Vautier 29, B 1000 Brussels, Belgium. ericsimon98brach@gmail.com