Search publications of the members of the Royal Belgian institute of natural Sciences
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New species, Combinations and records of Jumping Spiders in the Galapagos Islands (Araneae: Salticidae)
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Crassostrea gigas or Magallana gigas: A Community-based Scientific Response
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Stratigraphy and depositional environments of the Late Famennian (Late Devonian) of Southern Belgium and characterization of the Strud locality
- The Famennian (Upper Devonian, c. 372 to 359 Ma) strata of Belgium have recently received much attention after the discoveries of early tetrapod remains and outstandingly preserved continental arthropods. The Strud locality has yielded a diverse flora and fauna including seed-plants, tetrapods, various placoderm, actinopterygian, acanthodian and sarcopterygian fishes, crustaceans (anostracans, notostracans, conchostracans and decapods) and a putative complete insect. This fossil assemblage is one of the oldest continental – probably fresh-water – ecosystems with a considerable vertebrate and invertebrate diversity. The study of the palaeoenvironment of the Strud locality is crucial because it records one of the earliest and most important phases of tetrapod evolution that took place after their emergence but before their terrestrialization. It raises the question of environmental and ecological conditions for the Devonian aquatic ecosystem and the selection pressures occurring at the onset of tetrapod terrestrialization. The present study characterized the fluvial facies of the Upper Famennian sedimentary rocks of Strud and the surrounding areas. The exceptional preservation of arthropods and plants in the main fossiliferous layers is explained by rapid burial in the fine-grained sediment of the quiet and confined flood plain environment. Newly investigated fossiliferous sections in the Meuse–Samson area led to the description and correlation of key sections (Strud, Wierde and Jausse sections, complemented by the less continuous Haltinne, Huy and Coutisse sections). Moreover, the investigated sections allowed a review of the age of the fossiliferous horizon, which is now definitely considered to be Late Famennian in age.
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Brabantophyton, a new genus with stenokolealean affinities from a Middle to earliest Upper Devonian locality from Belgium
- A new taxon with stenokolealean affinities, Brabantophyton runcariense gen. et sp. nov., is described from seven pyrite permineralized axes collected from the mid Givetian to earliest Frasnian (late Middle to earliest Upper Devonian) locality of Ronquières (Belgium). The specimens include stems and lateral organs. The stems are characterized by a protostele dissected into three primary ribs, each of them dividing into two secondary ribs. The protostele shows a central protoxylem strand and numerous strands distributed along the midplanes of the ribs. The vascular supply to lateral organ is composed of two pairs of traces, produced at the same time by the two ribs issued from a single primary rib of the protostele. Within each pair, the shape and the size of the traces are unequal: one is T-shaped and the other is oval to reniform. The T-shaped traces of each pair face each other. The inner cortex of the lateral organs is parenchymatous and the outer cortex is sparganum-like. The specimens of Brabantophyton runcariense show many similarities with the stenokolealean genus Crossia virginiana Beck and Stein, but the vascular supply of lateral organs of the latter consists of a more symmetrical and distinctively simpler pair of traces. Brabantophyton represents the first report of the Stenokoleales in southeastern Laurussia. The characteristics of the Brabantophyton protostele compare better with the anatomy of the radiatopses, and, within the latter, particularly with basal seed plants.
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New information, including anatomy of the secondary xylem, on the genus Brabantophyton (Stenokoleales) from Ronquières (Middle Devonian, Belgium)
- Two pyrite permineralized stems and one root are reported from the upper Middle to lowermost Late Devonian (middle Givetian to lowermost Frasnian) locality of Ronquières (Belgium) and identified as Brabantophyton runcariense Momont et al. (Stenokoleales). The stems include a three-ribbed protostele with a central protoxylem strand and other strands disposed along the midplanes of the ribs; each specimen shows secondary xylem. Tracheids of both primary and secondary xylem show circular to elliptical, multiseriate bordered pits. Rays are 1–seriate to 4–seriate; their height is highly variable, ranging from 3 to more than 100 cells. The root includes a four-ribbed protostele. Each rib shows two exarch protoxylem strands. The root also comprises a ring of secondary xylem identical to that of the stems. The characteristics of the secondary vascular anatomy of Brabantophyton appear closer to the seed plants than to any other Devonian plant lineage. However, the presence of a bifacial vascular cambium is not demonstrated, which precludes a definitive assignment of the genus to the lignophytes. A hypothesis about the ontogenetic development of Brabantophyton is proposed on the basis of the different characteristics observed in the different stem specimens of the plant.
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Disrupted continental environments around the Devonian-Carboniferous Boundary: introduction of the tener event
- Recent refinements of the palynological stratigraphic scheme around the Devonian-Carboniferous Boundary in southern Belgium result in new questions on the effect of the Hangenberg Biocrisis on spores and on the validity of some ‘biozones’. Verrucosisporites nitidus, the guide taxa of the last Devonian palynozone (LN zone) is lacking in many sections and its presence is only acknowledged in proximal settings. Hence the LN zone is considered as an ecozone rather than a biozone. Moreover, investigation of the uppermost part of the uppermost Famennian shows that the palynological assemblages is dominated by abnormal forms of Retispora lepidophyta, notably by R. lepidophyta var. tener which seems to be characteristic of this interval in Western Europe. It is thus proposed to introduce the global tener event as a potential marker of the Hangenberg Biocrisis on land and in proximal marine settings. This profusion of abnormal spores is thought to be related to climatic variation possibly in link with global cooling below the Devonian-Carboniferous Boundary.
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Philippine mossy forest stick insects: first record of the genus Otraleus Günther, 1935 in the country, with four new species, and the new genus Capuyanus gen. nov. (Phasmida, Diapheromeridae, Necrosciinae)
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Plant-insect interactions in the Selandian (Early Paleocene) Gelinden Fossil Flora (Belgium) and what they mean for the ecosystems after the Cretaceous-Paleogene mass extinction
- This study aims to quantify the intensity and diversity of plant-insect associations observed in the fossil assemblage of Gelinden, Limburg, Belgium. The site yields a rich collection of well-preserved plant remains, mainly leaves, from a Paleocene European temperate forest. The 780 specimens presented here were scanned using standardized morphotype systems for any trace of damage. This raw data was then used to quantify the intensity and diversity of interactions in the Gelinden flora. This material showed an impressive richness of interactions, contrasting with the poor North American sites covering the period that followed the Cretaceous-Paleogene extinction. Both hosts and interaction types observed at Gelinden are two to three times more abundant than in most American floras, in raw numbers and leaf area affected. This is coherent with what has been observed in the few other studies conducted in Europe, South America and Antarctica, pointing toward more regionalized effects of the extinction than previously assumed based on American findings. This greater richness implies that these sites were either less affected or quicker to recover from the Cretaceous/Paleogene extinction, questioning its global impact, at least on the lower levels of the food web, as discussed in the following paper.
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Revisiting the Rebreuve plant assemblage from the Lower Devonian of Artois, northern France
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Revisiting the Rebreuve plant assemblage from the Lower Devonian of Artois, northern France
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Revisiting the Rebreuve plant assemblage from the Lower Devonian of Artois, northern France
- French Lower Devonian floras are rare, especially compared to certain other Western European countries. In this study, we reassess an assemblage collected in the 1930s in the Rebreuve quarry (Pas-de-Calais, northern France). We describe new features in several taxa and update taxonomic names from original descriptions. For instance, re-examination of vegetative remains previously described as Psilophyton princeps, led to the discovery of fertile structures allowing us to refer these specimens to Sawdonia. In total, this flora consists of 10 taxa, including up to four different Psilophyton species, such as P. parvulum. Other taxa include Danziella artesiana, Drepanophycus cf. spinaeformis, Sporogonites exuberans and some speci-mens of Taeniocrada and Sciadophyton, revealing a diverse Lower Devonian plant assemblage. The Rebreuve assemblage represents a typical Emsian flora from Laurussia and bears striking resemblance with coeval Belgian assemblages. Previous palynological investigations, in addi-tion to the similarities with well-dated Belgian floras, suggest an early Emsian age for this assemblage. The paleogeographical implications of findings are discussed.
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Porongodendron minitensis gen. nov. sp. nov. a new lycopsid from the Mississippian of Argentina with adaptations to tundra-like conditions
- The Mississippian is characterized worldwide by a general cooling of the environment and a climatic stratification of Earth. Argentina at that time was part of the megacontinent Gondwana. It occupied a position close to the South Pole around 60°S. Whereas paleoequatorial and paleotropical floras are relatively well known, higher latitude environments are still poorly understood. In this framework, a revision of Mississippian deposits is ongoing in Argentina. An extensive and detailed survey of the Sierra de las Minitas (La Rioja Province, western Argentina) involved drawing detailed sections and the systematic verification of all rock layers. Fossils were sampled and studied in the laboratory. We describe a new isoetalean lycopsid with a rare combination of characters. This plant presents an estimated low stature (approximately 30 cm), a branched rhizomorph, an inflated intermediary zone, a monocaulous growth form and evidence for cyclic fertility. These features are interpreted as representing specific adaptations to the harsher tundra conditions prevailing in the Lower Carboniferous Southern Polar environments.
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Morphological disparity of extant and extinct pinaceous ovulate cones: How many cones are enough?
- Abstract Premise The expansion of Pinaceae during the Cretaceous is exemplified by the numerous ovulate cone taxa found in western Europe and North America. The Belgian Wealden facies deposits have delivered hundreds of exceptionally well-preserved yet isolated pinaceous ovulate cones; these cones were placed by convention within form-genera. Ten species have been described in Belgium, representing about 20% of the known fossil record of this period. However, the validity of these taxa is questionable because their intra- and interspecific variabilities have never been thoroughly studied. Moreover, quantifying the expansion of Pinaceae in terms of morphospace occupation is desirable to reveal the dynamics of this critical radiation. Methods We used linear and geometric morphometry to quantify the shape of the extensive sample of Cretaceous cones of Belgium. These methods were also applied to extant pinaceous species to compare the morphological disparity of Cretaceous assemblages against those of today in selected ecosystems. We used ordination methods (PCA) to visualize morphospace occupation and test for species delineation. Results The morphological disparity was not higher in fossil species than in extant species we sampled. Both morphological approaches confirmed that the species Pityostrobus andraei presents high morphological variability. Our resampling tests indicate that ovulate cone morphological variability can be satisfactorily quantified with as few as 15 specimens. Conclusions The methodology used here is relevant for quantifying both the variability and the diversity of many fossil assemblages, paving the way for a more robust evaluation of Cretaceous pinaceous diversity.
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Morphological disparity of extant and extinct pinaceous ovulate cones: How many cones are enough?
- Premise The expansion of Pinaceae during the Cretaceous is exemplified by the numerous ovulate cone taxa found in western Europe and North America. The Belgian Wealden facies deposits have delivered hundreds of exceptionally well-preserved yet isolated pinaceous ovulate cones; these cones were placed by convention within form-genera. Ten species have been described in Belgium, representing about 20% of the known fossil record of this period. However, the validity of these taxa is questionable because their intra- and interspecific variabilities have never been thoroughly studied. Moreover, quantifying the expansion of Pinaceae in terms of morphospace occupation is desirable to reveal the dynamics of this critical radiation. Methods We used linear and geometric morphometry to quantify the shape of the extensive sample of Cretaceous cones of Belgium. These methods were also applied to extant pinaceous species to compare the morphological disparity of Cretaceous assemblages against those of today in selected ecosystems. We used ordination methods (PCA) to visualize morphospace occupation and test for species delineation. Results The morphological disparity was not higher in fossil species than in extant species we sampled. Both morphological approaches confirmed that the species Pityostrobus andraei presents high morphological variability. Our resampling tests indicate that ovulate cone morphological variability can be satisfactorily quantified with as few as 15 specimens. Conclusions The methodology used here is relevant for quantifying both the variability and the diversity of many fossil assemblages, paving the way for a more robust evaluation of Cretaceous pinaceous diversity.
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L’environnement de vie des premiers tétrapodes de Belgique
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Flabellopteris lococannensis gen. et sp. nov.: A new fern-like plant from the Famennian of South Africa
- A new fossil plant, Flabellopteris lococannensis Gess and Prestianni gen. et sp. nov., is described from the Famennian of South Africa. This plant is interpreted as monopodial in habit with a first order axis that only occasionally dichotomizes. The lateral organs (both branches and appendages) are borne spirally on all branching orders and a 1/3 organotaxy is suggested. The first order axes bear both second order axes and fertile appendages at the same nodes. Axes of the second and third branching orders bear appendages made of several isotomous dichotomies. Recurved paired sporangia are borne on dichotomizing appendages that are like the vegetative appendages. The plant bears some similarity to the Iridopteridales but also to the Late Devonian Rhacophytales and to the Lower Carboniferous fernlike plant Chlidanophyton dublinensis. The architecture of the plant is briefly discussed and its implication on the evolution of the frond is considered.
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The diversity of French Albian Pinaceae: a preliminary study of the Fliche (1896) material
- The Albian Gault Clay and Greensand Formation from the Argonne region (France) have yielded numerous plant remains including wood and an abundant (ca 100 specimens) collection of cones. Saporta (1880) and Fliche (1896) described some of these fossils that were attributed to seven species within Pinus. Two of these species have since been redescribed and renamed Pityostrobus oblongus Fliche 1896 and Pityostrobus argonnensis Fliche 1896 (Fliche 1896). The remaining five species, viz., Pinus praemontiloca Fliche 1896, P. wohlgemuthi Fliche 1896, P. praelepensis Fliche 1896, P. saportana Fliche 1896, and P. mammilifer Saporta 1880, still need to be restudied. We revised this material using X-ray micro-tomography and morphometry. We discuss the results of this work and try to clarify their taxonomy. In addition to the aforementioned published material, several specimens remained undescribed. Our preliminary results indicate, together with a new morphotype of pollen cone, the presence of at least two new morphotypes of ovulate cones. Some of the latter share many characters with Pinus, such as a very pronounced dorsal umbo. This high diversity matches that found in the Barremian–Aptian of Belgium and confirms the important diversity of Pinaceae in Western Europe during the Early Cretaceous.
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The benthic foraminiferal response to the mid-Maastrichtian event in the NW-European chalk sea of the Maastrichtian type area
- The mid-Maastrichtian carbon isotope event (MME), dated at ∼69 Ma, reflects a perturbation of the global carbon cycle that, in part, correlates with the enigmatic global extinction of ‘true’ (i.e., non-tegulated) inoceramid bivalves. The mechanisms of this extinction event are still debated. While both the inoceramid extirpation and MME have been recorded in a variety of deep-sea sites, little is known about their expression in epicontinental chalk seas. In order to study the shallow-marine signature of the MME in this epicontinental shelf sea, we have generated quantitative foraminiferal assemblage data for two quarries (Hallembaye, NE Belgium; ENCI, SE Netherlands) in the Maastrichtian type area, complemented by a species-specific benthic δ13C record. In contrast to deep-sea records, no significant changes in benthic foraminiferal assemblages and benthic foraminiferal accumulation rates are observed across the MME in the type-Maastrichtian area. At the Hallembaye quarry, the otherwise rare endobenthic species Cuneus trigona reaches a transient peak abundance of 33.3% at the onset of the MME, likely caused by a local transient change in organic matter flux to the seafloor. Nevertheless, high and near-constant species evenness shows that neither oxygen nor organic matter flux was limited across the extinction level or during the MME. Benthic foraminiferal data from the uppermost part of the studied section, above the MME, indicate a significant increase in food supply to the seafloor. Decreased amounts of terrigenous elements across this interval document a lesser riverine or aeolian influx, which means that the increased benthic productivity is linked to a different origin. Potentially, the continuous precipitation of chalk under nutrient-poor conditions in the Late Cretaceous chalk sea was enabled by efficient nutrient recycling in the water column. In shallower depositional settings, nutrient recycling took place closer to the seafloor, which allowed more organic matter to reach the bottom. These results provide insights in the importance of nutrient cycling for biological productivity in the NW-European chalk sea.
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Identification of Funding Priorities. Document OTSOPA 22/02/02 presented by Belgium and France at the Meeting of the Working Group on Operational, Technical and Scientific Questions Concerning Counter Pollution Activities (OTSOPA)
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Discussion document on the status of the MAVI Working Groups on Strategic and Operational aspects (MAVI-SOWG) and Technical aspects (MAVI-TWG) and possible pathways towards a MAVI project proposal. Document OTSOPA 22/02/03 (+ Add. 1+2) presented by Belgiu
