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Seed plant evolution around the Devonian/Carboniferous boundary : reproductive vs. vegetative disparity.
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The origin of the ovule during the Devonian period represents one of the most significant events in the history of life on Earth that allowed seed plants to colonise new habitats and to successfully reproduce without available free water. Their evolution however remains tantalising, as no convincing transitional character states with free-sporing ancestors have been found. The first evidences of “extreme” heterospory are found in the Givetian with the occurrence of seed-megaspores such as Spermasporites allenii or Granditetraspora zharkovae. Another type of dispersed organ occurs in coeval deposits: the controversial proto-ovule Runcaria heinzelinii. This taxon is composed of a rounded apically modified megasporangium surrounded by two whorls of tissue. The earliest “true” ovules are found in the Upper-Devonian. They were cupulate, presented a dissected integument and a hydraperman type nucellus. Based on variation of these organs, up to 17 species have been described in Famennian deposits where they already show a wide morpho-anatomical disparity. Because they are most often found dispersed, the available information on the corresponding vegetative systems is very scarce. Based on material from Belgium and from the literature, we here document the vegetative systems of almost all types of Devonian seed plants for which ovules have been described. They show a very narrow diversity when compared to fertile parts, as only one morphology was found. It consists in a “zig-zag”-shaped main axis bearing helically arranged dichotomous branching systems. These new results will be compared with the data available for the Lower Carboniferous. Multivariate analyses indicate that the morpho-anatomical disparity of ovules during that time was comparable to that of the Devonian. In contrast, we observe a much higher disparity for the vegetative parts, with the apparition of various growth habits and new characters of the primary and secondary vascular system. This apparent decoupling between the diversification of seed plants reproductive and vegetative systems will be discussed.
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Selective representation of sediment sources in tsunami deposits from the Shetland Islands (UK)
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RBINS Staff Publications 2019
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Selective representation of sediment sources in tsunami deposits from the Shetland Islands (U.K.)
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RBINS Staff Publications 2019
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Semi-optimised pipeline routing for CO2 Capture and Storage
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RBINS Staff Publications
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Sentinel-1 data and PSI Techniques for Monitoring Inter-Seismic Earth Deformation
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RBINS Staff Publications
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Séquences polliniques en Flandre Sableuse (Nord-Ouest de la Belgique) : apport du paléoenvironnement à la compréhension des systèmes d’occupations préhistoriques
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Après trois décennies de recherches archéologiques en Flandre Sableuse (Nord-Ouest de la Belgique), une des régions actuellement les plus intensivement prospectées de l’Europe du Nord-Ouest, des cartes de répartitions archéologiques détaillées ont pu être établies. Celles-ci montrent une occupation préhistorique importante dès ca 12000 cal BC, couvrant les périodes du Paléolithique Final, du Mésolithique et du Néolithique, mais aussi et surtout un patron de distribution distinct des sites tant au niveau spatial que temporel. Dans le but d’expliquer les changements observés dans la localisation des sites, un projet interdisciplinaire faisant intervenir archéologie, géographie, paléoécologie, sédimentologie et prospection géophysique a été entrepris. L’idée sous-jacente est que, outre les facteurs humains, les conditions environnementales ont pu avoir une influence sur les conditions d’occupation au cours du temps. L’objectif de cette recherche est donc d’analyser l’histoire du peuplement de cette région en termes de potentiels environnementaux. En effet, depuis la fin du dernier Pléniglaciaire, le paysage de la Flandre Sableuse a été sujet à des changements importants dus à des fluctuations climatiques abruptes, et de nombreux lacs peu profonds et de dunes de sables ont été formés, jouant certainement un rôle majeur dans la dynamique d’occupation du territoire. Lors d’une importante campagne de terrain, 15 sondages mécaniques et une tranchée ont ainsi été réalisés à 5 emplacements différents selon un transect Nord-Sud : sur une crête sableuse, au sein de dépressions lacustres fossiles et d’anciennes petites ravines incisant ces dernières, dans de larges paléochenaux. Ces profils ont été intensivement échantillonnés en vue d’analyses paléoécologiques et sédimentologiques et pour les datations OSL et 14C. Nous présentons ici les résultats polliniques obtenus pour 4 de ces séquences sédimentaires. Ils aboutissent à une vison nouvelle de l’évolution des paléopaysages locaux et régionaux en Flandre Sableuse au cours du Tardiglaciaire et du début de l’Holocène, et permettent d’évaluer en détail comment et dans quelle mesure cette évolution a pu déterminer les occupations préhistoriques de cette région.
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Sex and transposable elements in ostracods (Crustacea, Ostracoda)
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Shastasaurid ichtyosaurs and other lost critters from the French Rhaetian
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RBINS Staff Publications
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Sheep and goat birth seasonality at Early Byzantine Sagalassos
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The seasonality of birth, a key parameter when addressing past domestic livestock management, can be investigated through serial stable oxygen isotope analysis in tooth enamel. The assessment of the season of births requires furthermore the availability of modern reference data set, existing for cattle, sheep, pigs or llamas. The ancient site of Sagalassos, in the Taurus Mountains (SW Turkey), has delivered a large assemblage of sheep and goat remains. The osteological analysis revealed a predominance of goat over sheep, with a ratio varying between 65 and 90% over time. Goats and sheep were kept at an old age for the production of milk, wool/hair, as well as for horn-working and hide exploitation. A stable oxygen isotope (δ18O) analysis focussing on mandibular M2s was undertaken to investigate goat and sheep livestock demographic management during the Early Byzantine period (450-680 CE). ZooMS was used to confirm specific attribution of selected specimens (ten goats, eight sheep). Ten modern hair goats collected in the late 1990s in the context of a research project on small ruminant herd management in the Eastern Mediterranean were also sampled to provide a modern comparative for the assessment of birth season. The modern goat δ18O sequences were modelled according to Balasse et al. (2012) and compared with the existing sheep reference data set. The comparison suggests a different timing in the isotope record between sheep and goats and argues for the use of species-specific comparative for the assessment of birth season in archaeological herds. The comparison of the modern and archaeological goat δ18O sequences indicate a quite restricted season of births in spring for the latter. On the contrary, sheep births were spread out over roughly six months, from late winter/early spring to early-/mid-summer. More modern goat comparatives are needed to enrich this dataset. Keywords: Stable oxygen isotope, tooth enamel, birth seasonality, goat, Sagalassos.
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RBINS Staff Publications 2023
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Shell morphology and reproductive anatomy of the genera Bensonies, Khasiella, Oxytesta and Macrochlamys (Pulmonata: Ariophantidae: Macrochlamydinae) from Nepal
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