Diplocynodon is an enigmatic extinct genus that is generally considered to be part of the Alligatoroidea, Crocodylia. While Alligatoroidea potentially originated in North America, Diplocynodon only has a fossil record in Europe, dating from the middle Eocene to middle Miocene (c. 45–15 Ma). The study of Diplocynodon remains curated in palaeontological collections could aid research on the morphology, phylogeny, evolution and biogeography of this large and widespread genus. We describe the Diplocynodon material in the historical Filhol collection of KU Leuven, collected at Saint-Gérand-le-Puy (early Miocene) and Ronzon (early Oligocene), from central France in the late 19th century. The aim was to identify which remains reside in the Filhol collection and to deduce the systematics behind these remains, making the collection more accessible to future research. A total of 781 skeletal elements were catalogued, including both cranial and post-cranial bones. The most complete and anatomically representative specimens were photographed. Based on characteristic features, the remains from Saint-Gérand-le-Puy were confirmed as D. ratelii, a taxon that has previously been described from that locality. The remains from Ronzon could not be confidently determined in the present study.
In the loess stratotype of Belgium, in Romont quarry (Bassenge), minerals of a volcanic ash-fall deposit are dispersed in large quantities as a cryptotephra within a fossil humic horizon dating back to the end of the Weichselian Early Glacial. Chemical analysis of pyroxenes and amphiboles indicates that those minerals belong to the Rocourt Tephra as described in another four reference localities. The stratotype of this tephra is thus maintained in this quarry, as it is the only site of high chronostratigraphic value where it is still accessible.
The merit of the low-field magnetic susceptibility as proxy parameter is concisely reviewed. In many geological samples it is a composite consisting of a diamagnetic, paramagnetic, and ferromagnetic (sensu lato) contribution that varies with rock type. For weakly magnetic samples, the diamagnetic and paramagnetic contributions are an appreciable portion of the measured susceptibility. In such materials equating the measured susceptibility with the ferromagnetic susceptibility is not warranted. Before a susceptibility record is geologically interpreted, the underlying drivers of its variation must be understood. This is achieved by integrating susceptibility data with an extended magnetic property analysis, geochemical information, and a paleomagnetic assessment of the timing of the acquisition of the natural remanent magnetization as the magnetic minerals may post-date the sedimentation age. Measuring the susceptibility at several frequencies and in varying low applied fields provides important information on the grain-size distribution in the ultrafine grain end and, to a lesser extent, on the magnetic mineralogy. Examples discussed include research into loess/paleosol records and high-resolution time scale development. Variable surficial oxidation of magnetite particles and potential remagnetization complicate the interpretation of a susceptibility record in terms of paleoclimate.
Three tests of the holasteroid echinoid Hemipneustes striatoradiatus from the Belgian-Dutch type area of the Maastrichtian Stage preserving evidence of vertebrate-invertebrate interactions are documented and analysed. One specimen exhibits adoral pentagonal puncture marks and a large aboral scar from a mosasaur attack, with Mosasaurus hoffmannii as the presumed predator. A second test preserves evidence of two separate attacks, the first by a mosasaur, presumably Plioplatecarpus marshi, leaving both a pentagonal adoral scar and a large aboral one, and the second by a shark, leaving nonpenetrating small, deep triangular pits with tapering tails. A similar pitting is seen on the third test, arranged in clusters and here interpreted as a shark bite from above followed by a second bite subsequent to a 90 degrees rotation of the echinoid. These finds provide the first unambiguous evidence of mosasaur predation on Hemipneustes and add to the sparse record of shark-echinoid interactions, suggesting that predation on large holasteroids by vertebrates was more frequent than previously recognised. All three tests also exhibit syn vivo and postmortem invertebrate interactions, including also an undescribed serpulid.
Three drill holes in the Mons Basin yield together 350 m of Coniacian to Campanian chalk cores. Detailed geological logging was conducted on the well-known Trivi & egrave;res Chalk, SaintVaast Chalk, and Maisi & egrave;res Chalk formations. A thorough sedimentological characterization was performed, from macrofacies to SEM microtexture. Petrographic observations and geochemical analysis indicate eogenetic calcite cementation and phosphatization in two benchmark levels, already known for their high glaucony content, namely in the Trivi & egrave;res Chalk Formation and the Maisi & egrave;res Chalk Formation. Upwelling currents, prevalent during the Late Cretaceous, are likely the source of the phosphates, and the cause of reduced sedimentation rates. Strong anoxic currents resulted in the formation of hardgrounds, the development of glaucony pellets and pyrite formation within shallow subtidal sediments. Multiple conglomeratic chalk intervals were identified in the Trivi & egrave;res Chalk Formation. They likely result from local sediment destabilization due to extensional tectonic activity. Moreover, the identification of deformation bands attests to synsedimentary tectonic activity within the basin. Overall, this research unravels various phenomena, including marine currents, sea-level fluctuations, and tectonic activity, that influenced chalk deposition in the Mons Basin. This research enables enhanced comprehension and forecasting of the heterogeneities in chalk and its spatial variability.
The elasmobranch fauna of the middle Lutetian Asse Clay Member (the lower part of the Maldegem Formation) has been updated and complemented with new material from a temporary outcrop at Papenboskant (Wolvertem), about 20 km north of Brussels. This faunal assemblage, which exclusively comes from its coarse-grained glauconitic base, traditionally known as the bande noire, comprises 22 taxa. Fourteen are mentioned for the first time in this horizon, including Abdounia lapierrei, which has never been recorded in Belgium before, and Casierabatis spp. The latter comprises dental morphologies deviating from these of the two nominal Casierabatis species known to date, although it is currently unclear if these reflect intraspecific variability or represent taxonomic novelties. The new records from Papenboskant consist predominantly of small-toothed taxa, mainly batoids, which are absent from the historical handpicked museum collections of the Wemmel Sand and Asse Clay members reviewed in this study. The composition of the elasmobranch fauna indicates that during the middle Lutetian, the area north of Brussels was covered by a tropical to warmtemperate shallow sea with sandy to muddy bottoms and an open connection to deeper waters. The pronounced similarities between the assemblages of the Belgian, Hampshire, and Paris basins indicate that, during the middle and late Lutetian, these three subareas of the southern North Sea remained interconnected and maintained marine exchange with the Atlantic Ocean, not only through the northern seaway but also via the southwestern English Channel. Virtually all of the newly recovered elasmobranch taxa existed over a considerable period of time and were reported from several Ypresian and/or Lutetian deposits across the North Sea Basin. Abdounia lapierrei appears to possess biostratigraphic significance, being so far confined to Lutetian strata. This may also apply to certain representatives of the Casierabatis species group, although this remains to be confirmed. The single tooth of Notorynchus figured in Leriche (1905) and recovered from the Wemmel Sand Member at Neder-Over-Heembeek is re-examined and refigured. This specimen represents the first occurrence of Notorynchus kempi in Belgium.
Two Devonian asteropygine trilobite specimens exhibiting rare cases of encrustation are recorded. An almost fully articulated exoskeleton of Rhenops australocustos from the lower Emsian in Luxembourg carries hederelloid colonies on its cephalon and thorax. The colonies are interpreted to have attached syn vivo (i.e. to the living trilobite) and the relation with their host was likely commensal. A cephalon of Philonyx philonyx from the upper Emsian in Germany exhibits five putative morphotype encrusters identified as hederelloids, auloporid corals, cornulitids, bryozoans and foraminifers. This is the first documented evidence of a foraminifer on a trilobite host. This cephalon is either a moult or a carcass.
In the Neufchâteau–Eifel Synclinorium (southern Belgium), remnants of the spoil heap of the disused and now flooded underground Sainte-Barbe Quarry (Warmifontaine) yielded an invertebrate Pragian assemblage occurring in the dark monotonous slates of the La Roche Formation (Martelange Member). This locality is considered as a new Belgian Konservat-Lagerstätte (fossil conservation deposit) due to the presence of both biomineralised and soft-bodied organisms. Two specimens from the Sainte-Barbe Quarry Biota are described and assigned to two distinct classes of extinct echinoderms. The first one corresponds to an almost complete, flattened and distorted dendrocystitid solutan, which is tentatively identified as Dehmicystis? sp., based on similarities with D. globulus from the Hunsrück Slate (Emsian) of Germany. The second echinoderm specimen is a well-preserved, flattened, fully articulated and almost complete mitrate stylophoran, morphologically close to Mitrocystites? styloideus-like peltocystidans from the Lower and Middle Devonian of Germany. Taphonomic attributes of the two echinoderms from Warmifontaine (e.g. both fully articulated; mitrate with its aulacophore preserved in feeding position) suggest they were probably killed and entombed by obrution deposits in an otherwise quiet and deep setting. Other echinoderms (asteroids, crinoids, blastoids, cyclocystoids, ophiuroids) reported from the Lower Devonian of Belgium are also briefly discussed and illustrated (e.g. holotypes).
Though the Neogene deposits of northern Belgium yielded many marine vertebrate remains, including cetaceans, the fossil record of several clades remains scarce. Among echolocating toothed whales (Odontoceti), cranial fossils of early delphinidans generally referred to the family Kentriodontidae are surprisingly rare in the Miocene units of the Antwerp area. Recently, a large construction pit excavated in the city centre of Antwerp allowed for the lithostratigraphic description of a section in the Kiel and Antwerpen members of the Berchem Formation. In addition to an elasmobranch assemblage of 13 species, a well-preserved, tiny odontocete cranium was discovered in the lower part of the Antwerpen Member (Middle anatomical similarities with the small kentriodontid Kentriodon pernix, originally found in such a young individual, highly unusual anatomical traits, especially in the orbit region, are interpreted as resulting from a malformation that occurred relatively early during cranial
The homalonotid trilobite Burmeisterella delattrei is recorded from the early Emsian Ruisseau de la Forge Formation in Belgium (southern limb of the Dinant Synclinorium), somewhat lower than its previously recorded first occurrence in the overlying Vireux Formation. The species may be considered an index fossil for the German Singhofen and Vallendar groups along with the homalonotids Burmeisterella armata and Digonus ornatus ornatus. A pygidium of B. delattrei from the Clervaux Formation in Luxemburg with one of the dorsal spines in place on the first pleural rib, allows a minor modification of current reconstructions of the dorsal exoskeleton to be proposed. The holotype and two paratypes (pygidia) of B. delattrei from the Vireux Formation in northern France are refigured. In total, four species of Burmeisterella, namely B. aculeata, B. armata, B. delattrei (= B. vixarmata) and B. quadrispinosa, are now recognised in the upper Pragian to lower Emsian of Belgium.
Twelve species and four forms of Middle Devonian rugose corals from Morocco are described and illustrated. The material comes from four localities of the Ma’der Basin whose age from the Late Eifelian to the base of the middle Givetian is based on conodonts. Three taxa are new: Marennophyllum kaufmanni n. sp., Stringophyllum pedderi n. sp. and Siphonophrentis subaequalis n. sp. Heliophyllum moghrabiense Le Maître, 1947 is the only taxon common to the four outcrops and it suggests an Eastern North American influence at the level of the genus. Siphonophrentis cantabrica Birenheide, 1978, first described from Spain, is also a North Gondwanan species whereas Stringophyllum acanthicum (Frech, 1885), Acanthophyllum heterophyllum (Milne-Edwards & Haime, 1851), A. vermiculare (Goldfuss, 1826) and Spinophyllum blacourti (Rohart, 1988) are interesting for correlations with Western Europe and sometimes with Eastern Europe. Enallophrentis corniformis (Gürich, 1896) was defined in Poland, also in the Old World Realm. Farther to the east, there is a link with China where Siphonophrentis cantabrica is present. Finally, it must be mentioned that Australophyllum Stumm, 1949 is observed for the first time in Morocco.
Borehole log correlations provide the first evidence for >15 m deep channel incision in the base of the Quaternary at the southern margin of the North Sea Basin. The coarse sand of the lower Quaternary Merksplas Formation fills up the channels that were cut into the top of the subjacent fine, glauconite-bearing shelly sand of the upper Pliocene Lillo Formation. Channel erosion was locally able to remove the entire upper sandy unit (Merksem Member) of the Lillo Formation. The interpretation of a seismic line in the area shows that the channel erosion reached even deeper at some locations. The very coarse, poorly sorted infill of the channels, with plenty of reworked material, testifies to deposition under tidal or tidally enhanced currents. The channel incisions probably cut into the Lillo Formation during the earliest Quaternary sea-level lowstands. During a subsequent sea-level rise, tides entered the paleo-valleys and widened them. Channel lag deposits were formed with abraded shells and other intraclasts. The latter are overlain by a thicker fining-upward sequence, which is indicative of channel fills and mainly composed of coastal environment-sourced quartz sand.
The Strunian regional substage corresponding to the uppermost Famennian of Belgium and northern France (Avesnois area) is marked by the occurrence of trilobites after an almost complete absence that began at the top of the Frasnian. The Strunian phacopid trilobites represented by Omegops, i.e., O. accipitrinus and O. maretiolensis, are recorded and illustrated from two Belgian sections (Spontin and Chansin) situated in the central part of the Dinant Synclinorium. These belong to the youngest known phacopids and they rank among the victims of the Hangenberg Crisis that took place near the Devonian–Carboniferous boundary. The phacopid fauna formed a trilobite association inhabiting a shallow shelf together with diverse brachiopod but also coral, crinoid, mollusc communities. These Belgian trilobites are compared with Omegops bergicus encountered in the northern France (Avesnois area).
Damaging earthquakes happened in the Hainaut coal basin (Belgium) in the 19th and 20th centuries but stopped after coal mining. We relocated 54 Hainaut earthquakes of the period 1965 and 1985 by using regional and local seismic phase measurements from recordings in and around Belgium. These new results finalise the Hainaut earthquake catalogue, derived from macroseismic data for the 1887-1965 period and instrumental records after 1965. This updated database allows us to discuss the origin of this intriguing seismicity. Computed focal depths show that the strongest earthquakes before 1985 occurred inside the Upper Palaeozoic part of the Brabant Parautochton, probably below the deepest parts of the coal mines. The shallowness of this seismicity, its spatial link with the coal basin, the compressive to strike-slip focal mechanisms of the stronger earthquakes between 1965 and 1985 and the large quantity of coal mass removal all match with worldwide observations of mining-triggered earthquakes. The earthquake mechanisms agree with the local, compressive to transpressive stress regime derived from differences in upper crustal density and topography that make the Hainaut area more sensitive to fault reactivation at shallow depths, as observed in similar tectonic settings elsewhere in the world.
The revision of the lithostratigraphic scale of southern Belgium, based on the revised geological map of Wallonia and recent stratigraphic and sedimentological works, has led to the re-definition of 63 lithostratigraphic units for the Middle Devonian Series. Although most of the units described in the present overview are classical subdivisions of the Belgian lithostratigraphic scale, updates on their definition, boundaries and age were required and are provided herein. New terms are introduced for remarkable beds and facies. Groups are introduced to gather formations that are difficult to separate on geological maps, whereas some previously described formations are here retrograded to member status. The Middle Devonian units recorded the development of the carbonate factory in the Eifelian, interrupted by siliciclastic deposits followed by the development of a wide carbonate shelf during the Givetian. Reefs occur both in the Eifelian (offshore bioherms, biostromes on platforms) and in the Givetian (biostromes). The vertical succession and lateral correlation of the lithostratigraphic units allow to reconstruct the evolution of the shelf from the early Eifelian to the demise of the carbonate shelf at the end of the Givetian.
The lithostratigraphic scale of Belgium, which is the cradle of several global Devonian stages, has been revised after completion of the update of the Geological Map of Wallonia (Carte g & eacute;ologique de Wallonie) at a scale of 1/25,000 and recent stratigraphic and sedimentological research. As a result, 100 lithostratigraphic units (groups, formations, members, facies, horizons) for the Upper Devonian Series have been re-defined. Whereas most of the units discussed in this overview are traditional divisions of the Belgian lithostratigraphic scale, this update includes revisions to their definitions, boundaries, and ages. New terms have been introduced essentially for notable horizons and facies. Additionally, some previously described formations have been reclassified as members as they are difficult to distinguish and separate on geological maps. The Frasnian lithostratigraphic units reflect the development of mixed argillaceous-carbonate deposits during the major transgressions that culminated at the end of the stage. This was followed by the gradual emergence of littoral siliciclastic facies that took place during the Famennian regression. Re-installation of carbonate deposits was recorded during the latest Famennian (Strunian transgression), heralding the lower Carboniferous carbonate succession to come. Reefs occur in the Frasnian remarkable.
The revision of the lithostratigraphic scale of southern Belgium, based on the revised Geological Map of Wallonia and recent stratigraphic and sedimentological works lead to the re-definition of 79 lithostratigraphic units for the Lower Devonian Series. Most of the units described in the present paper are classical subdivisions of the lithostratigraphic scale but updates on their definition, boundaries and age are provided here. New terms are introduced for remarkable beds and facies. Groups are introduced to gather formations than are rarely separated on geological maps whereas some units previously described as formations are here retrograded to members. The dominant lithologies of the Lower Devonian of Belgium reflect siliciclastic sedimentation in various depositional settings ranging from fluviatile conglomerate to estuarine and deltaic sandstone, tidal siltstone and distal delta-front shale on the southern margin of the London-Brabant Massif and around other Caledonian inliers (e.g. Rocroi, Stavelot-Venn). The vertical succession and lateral correlation of the lithostratigraphic units allow to reconstruct the evolution of the shallow basin from the latest Silurian (Pridoli) to the latest Emsian.
The northeastern coastal plain of Belgium was a well-developed region during the late medieval period when Bruges and a series of smaller harbours became connected to the North Sea via the Zwin tidal channel. Yet, ecological data related to the evolution of the regional environment of the former Zwin region are still lacking. Diatoms, pollen, and macrobotanical remains have been studied for the first time from two cores drilled in the surroundings of the lost harbour of Hoeke. The sediments in both cores were deposited in four successive tidal channel systems spanning the pre-Roman to late medieval periods. Marine tychoplanktonic and planktonic diatoms were dominant and confirmed the presence of open marine tidal channels, while marine epipsammic diatoms were specific to channel deposits (systems 1 and 4) and marine epipelic diatoms characterised channel and accretion deposits (systems 2 and 3). The sediments of the late medieval Zwin main channel and tributary (system 4) are both characterised by marine tychoplanktonic and epipsammic species. The palynomorphs were typical of marine tidal deposits and (reworked) peat, while macroremains pointed to freshwater plants growing in the vicinity. The palynomorphs (system 4) suggest a more open landscape associated with the extensive reclamation and embankment of the Zwin region. Diatoms in the superjacent tidal deposits indicate that the late medieval Zwin silted up rapidly.
