Si le registre fossile des lézards est assez bon pour l’Eocène moyen et supérieur en Europe, il n’en va pas de même pour l’Eocène inférieur. Seule la localité de Dormaal, datant de l’Eocène basal (niveau-repère MP7,Belgique) semble faire exception. Parmi les nombreux fossiles de lézards de cette localité, nous présentons ici pour la première fois quelques rares éléments appartenant à un gecko. Ce dernier vivait donc dans nos régions durant le Maximum Thermique Paléocène-Eocène (PETM), climat le plus chaud des 66 derniers millions d’années. Ce nouveau taxon, daté de 56 Ma, est le plus ancien gecko cénozoïque connu en Europe. Avec Laonogekko lefevrei de Prémontré (MP 10, Bassin de Paris), plus jeune d’environ 5 millions d’années, ces taxons forment la radiation du Paléogène inférieur de ce clade. Aujourd’hui, les geckos sont répartis dans le monde entier, principalement dans les zones tempérées chaudes à tropicales, bien que certaines espèces puissent atteindre des régions plus froides dans les hémisphères Nord et Sud. Le nouveau gecko de Dormaal représente un élément thermophile, confirmant les préférences thermiques actuelles des geckos. Par ailleurs, la distribution de ce groupe dans des latitudes aussi septentrionales (au-dessus de 50° Nord) n’est pas surprenante durant cette période particulièrement chaude. Bien que le nouveau taxon décrit ici ne soit représenté que par un frontal et des dentaires (deux des éléments les plus fréquemment préservés chez les geckos fossiles), il fournit un nouveau record de diversité des squamates à la base de l’Eocène. Avec Yantarogekko de l’ambre éocène de la Baltique (district de Kaliningrad, nord-ouest de la Russie), ces geckos documentent la distribution septentrionale des geckos en Europe pendant l’Éocène.
Located in
Library
/
RBINS Staff Publications 2022 OA
The sustainable use and management of natural resources in border regions require unambiguous geological information from neighbouring countries. However, the available data often lack compatibility and the same level of detail across borders. Aim of the Belgian-Dutch H3O projects is to produce seamless, cross-border, 3D geological and hydrogeological models of the Cenozoic deposits across the border between Belgium and The Netherlands. “H3O – De Voorkempen” is the third consecutive project, focusing on the Noorderkempen (Flanders) and the western part of Noord-Brabant (The Netherlands). The project started in 2020 and the final results will be delivered in 2023. A crucial step in any cross-border geological modelling task is to establish the correlation between lithostratigraphic units on both sides of the border. In this project, the correlation is initially based on the available knowledge of regional lithostratigraphy (including chronology, depositional environment, sedimentological characteristics) and then further fine-tuned based on the interpretation of high-quality boreholes, geophysical well logs and seismic lines that cover the main geological complexities and cross the international border. The correlations are graphically presented in a chrono-lithostratigraphic correlation chart and cross-section profiles. The established correlation scheme will be used as a base for converting or reinterpreting the available data. In the final stage, the harmonized datasets will be used to create a geometrically and stratigraphically consistent 3D model of “De Voorkempen”. The result will be a state-of-the-art reference for the subsurface structure of the project area, which can be used as a base for scientific research and cross-border management of natural resources. The Belgian-Dutch H3O projects are carried out by a partnership between TNO – Geological Survey of the Netherlands, VITO and RBINS – Geological Survey of Belgium, with support from the Flemish Bureau for Environment and Spatial Development (VPO), Flanders Environment Agency (VMM), Province of Noord-Brabant and drinking water company Brabant Water. The geological models are/will be available in the public domain via the online data portals of DOV (Database of the Subsoil in Flanders) and DINOloket (Data and Information on the Dutch Subsurface). For the technical reports of previous H3O projects, see Deckers et al., 2014 and Vernes et al., 2018. References Deckers, J., Vernes, R.W., Dabekaussen, W., Den Dulk, M., Doornenbal, J.C., Dusar, M., Hummelman, H.J., Matthijs, J., Menkovic, A., Reindersma, R.N., Walstra, J., Westerhoff, W.E. & Witmans, N., 2014. Geologisch en hydrogeologisch 3D model van het Cenozoïcum van de Roerdalslenk in Zuidoost-Nederland en Vlaanderen (H3O-Roerdalslenk). VITO/TNO report, Mol/Utrecht, 208 pp. (incl. 8 appendices). Vernes, R.W., Dekkers, J., Bakker, M., Bogemans, F., De Ceukelaire, M., Doornenbal, J., den Dulk, M., Dusar M., Van Haren, T., Heyvaert, V., Kiden, P., Kruisselbrink, A., Lanckacker, T., Menkovic, A., Meyvis, B., Munsterman, D., Reindersma, R., Rombaut, B., ten Veen, J., van de Ven, T., Walstra, J. & Witmans N., 2018. Geologisch en hydrogeologisch 3D model van het Cenozoïcum van de Belgisch-Nederlandse grensstreek van Midden-Brabant / De Kempen (H3O – De Kempen). TNO/VITO/KBIN-BGD report, Utrecht/Mol/Brussel, 109 pp. (+8 appendices).
Located in
Library
/
RBINS Staff Publications 2021
Placentals are by far the most diverse group of mammals today, with 6,111 species. They occupy a plethora of ecological niches worldwide and display a broad range of body masses. The vacant niches left by non-avian dinosaurs and other vertebrates after the end-Cretaceous mass extinction provided a crucial opportunity for placentals to diversify; however, intrinsic factors also may have played a role. The general neurosensory organization exhibited by extant mammals has been maintained since the early Mesozoic. Much later, early members of extant placental groups from the Eocene and Oligocene including rodents, primates and artiodactyls—display neurosensory innovations such as a proportionally larger neocortex and higher encephalization quotient compared to their Mesozoic ancestors. However, between these two well-known intervals of mammalian neurosensory evolution, there is a gap: few studies have focused on the brains of the oldest placentals living during the early Paleogene, in the Paleocene. We focus on the ‘Arctocyonidae’, a likely polyphyletic group of ‘condylarths’, including species potentially implicated in the origins of some extant orders. ‘Arctocyonids’ were among the first placentals to diversify after the end-Cretaceous extinction. They have been reconstructed as small-tomedium sized, mainly omnivorous and terrestrial. We obtained cranial and bony labyrinth endocasts for Chriacus baldwini and C. pelvidens from the lower Paleocene of the San Juan Basin, New Mexico, and Arctocyon primaevus from the upper Paleocene of the Paris Basin, France, via high resolution computed tomography. Both share plesiomorphic brain features with previously described early Paleocene mammals. They have small lissencephalic brains with an EQ range of 0.12-0.43 and 0.16-0.31, respectively. The olfactory bulbs and the paraflocculi represent 6% and less than 1% of the total endocranial volume, respectively and the neocortical height ratio represents ~25% of the total endocranial height. Based on cochlear measurements, both taxa had hearing capabilities similar to those of extant wild boars. Agility scores between 2 and 3 were obtained for both taxa, similar to the modern American badger and crab-eating raccoon, suggesting that C. pelvidens and A. primaevus were ambulatory. These results support growing evidence that early placentals had lower EQs and less expanded neocortices compared to Eocene and later taxa, potentially indicating that high intelligence was not key to the placental radiation after the End-Cretaceous extinction. Grant Information: Marie Sklodowska-Curie Actions: Individual Fellowship, European Research Council Starting Grant, National Science Foundation, and Belgian Science Policy Office.
Located in
Library
/
RBINS Staff Publications 2019
