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Recent data on the enigmatic family Raoellidae: how aquatic…how cetacean?
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At the beginning of the 21st century, the discovery of an involucrum on the auditory bulla of Indohyus, a small raoellid artiodactyl from the Indian subcontinent, triggered the phylogenetic gathering of Raoellidae with the Cetacea clade, making them pivotal in addressing questions surrounding the land-to-water transition in Artiodactyla. Micro CT scan investigations and newly collected material from the Kalakot area (Jammu and Kashmir, India), recently greatly increased our knowledge of the cranial and dental features of this group. Here we present new data on cranial morphology of Raoellidae deriving from micro CT scan investigations of Indohyus indirae and Khirtharia inflata. This new body of data comprises investigations of the endocast of the braincase, the complete middle ear including the ossicles and auditory bulla, the petrosal bone, and the cast of the bony labyrinth. It also includes the reconstruction of the complete anterior dentition. This study gives us a comprehensive picture of the features of the Raoellidae head and improves our understanding of their semiaquatic habits. This increased knowledge of raoellids further extends the list of features they share with the first archeocetes, calling into question the definition of the clade Cetacea.
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RBINS Staff Publications 2025 OA
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First crocodyliform fossils from the Eocene of Indonesia
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The Paleogene crocodyliform record is rich in taxonomic diversity, preserving crown and stemeusuchians alongside late-surviving neosuchians and notosuchians. This richness is mainly known from the extratropical latitudes of the New World and Eurasia, contrasting a poorly sampled tropical record. Within the tropics, the Paleogene of low-latitude southeast Asia is comparatively undersampled, with the Eocene Krabi Formation of Thailand representing the southernmost fauna. This crocodyliform fauna is composed of orientalosuchins and gavialoids, consistent with more northern records from southern Asia. Here we describe the first crocodyliform fossils from the Eocene of Indonesia, collected from the middle-late Eocene Talawi Member of the Sawahlunto Formation, west Sumatra. The Talawi Member represents a coastal swamp environment, preserving invertebrates, fish, and turtles along with rare frog, snake, and mammal fossils. Recovered crocodyliform fossils are often isolated and disarticulated, consisting of cranial remains including a partial braincase and jaw fragments, as well as relatively abundant teeth and osteoderms, vertebrae, and at least two autopodial elements. Procoelous vertebrae indicate eusuchian affinities. Osteoderms are diverse, with keeled and keelless squared and subrectangular forms. High and low-crowned fluted tooth morphotypes compare favorably to coeval gavialoids and orientalosuchins. A ziphodont form is present, potentially a planocraniid or sebecosuchian. External morphology of the braincase, such as narrow basioccipital tubera, a basioccipital plate bearing a crest, and a large basisphenoid exposure suggest a non-gavialoid identity. This is supported by preliminary observations of highresolution microCT scans, which imply a lateral carotid foramen ventral to the metotic foramen and laterally aligned medial and lateral eustachian foramina. The Sawahlunto fauna extends the southernmost geographical range of the Eocene southeast Asian crocodyliform fauna and represents the first multitaxon crocodyliform fauna from equatorial Asia. The ziphodont teeth either represent the last-occurring Asian planocraniids in a tropical refugium, or an incursion of Gondwanan sebecosuchians from India into the Asian tropics.
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RBINS Staff Publications 2025 OA
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The biodiversity of the Eocene Messel vertebrates based on the Belgian Collections
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The paleontological collections of the Royal Belgian Institute of Natural Sciences include a beautiful collection of 393 vertebrate specimens from the Messel Pit: 58 fish, 18 amphibians, 79 reptiles, 108 birds and 130 mammals. This collection is the largest Messel collection outside Germany and belongs to the „big four” (Smith et al. 2024). It results from a fieldwork partnership with the Seckenberg Research Institute, Frankfurt between 1982 and 1988, so a few years before the Messel pit was listed in 1995 as UNESCO World Heritage site. With a few exceptions, most of the specimens have been collected by the Belgians. However, most of the specimens have been prepared by German preparators. Here we show the Messel biodiversity based on the Brussels collection. The collection is relatively well diversified and contains 24 type and figured specimens. Among them are remarkable specimens such as the holotype of the hyaenodont carnivorous mammal Lesmesodon edingeri, the paratypes of the trogon bird Masillatrogon pumilio and embalonurid bat Tachypteron franzeni, the exquisitely 3-D prepared turtle lovers Allaeochelys crassesculpta and armored crocodylia Diplocynodon deponiae, and the only skeleton of the basal perissodactyl Hallensia matthesi housed in a public collection. The archives related to this collection are currently being digitized and several new studies are now based on micro-CT scan technology allowing to „discover” hidden characters.
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RBINS Staff Publications 2025 OA
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Do diversification and dispersals of early Eocene perissodactyls differ from those of other modern mammals?
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Perissodactyls make their first appearance in the fossil record during the Paleocene-Eocene Thermal Maximum (PETM), 56 Ma ago, at the same time as most modern placental mammal orders. However, their early diversification remains unclear since all main groups (Equidae, Isectolophidae, Ceratomorpha, Ancylopoda and Brontotheriidae) appear at the same time with numerous genera and are already diverse, contrary to other modern mammal orders, which have a much lower diversity. Moreover, several early perissodactyl genera seem endemic to each of the three Holarctic continents, rather than cosmopolitan as is the case for other mammal groups. We investigate the early evolution of perissodactyls by analyzing a new dataset focusing on early species to obtain a new expansive phylogeny. This large-scale phylogeny shows that the number of early perissodactyl genera was over-estimated and supports the synonymy of several genera. In addition, many species that were named as “Hyracotherium” in the past (or sometimes “Eohippus”, the “dawn-horse”) are not actually closely related to horses, including Hyracotherium itself, but can be considered as basal perissodactyls. Among the latter, at least Pliolophus and Cardiolophus experienced vast and fast dispersals between North America, Europe and Asia, during the PETM. This paleobiogeographic scenario much resembles the one of other earliest Eocene mammals, which comprise genera that are often found in at least two continents, such as in artiodactyls, primates, carnivorans, hyaenodontids, hyopsodontids, phenacodontids or rodents. Here, we show that the paleobiogeographic distribution of earliest perissodactyls does not differ from that of other modern mammals.
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RBINS Staff Publications 2025 OA
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Tomography of three articulated perissodactyl skeletons from Messel
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The perissodactyls from the UNESCO World Heritage site of Messel (MP11; around 47 Ma) are among the most well-known fossils from this site, and belong to at least five different genera: three equoids (Propalaeotherium, Eurohippus, and Hallensia) and two tapiromorphs (Lophiodon and Hyrachyus). Here, we investigated by X-ray microtomography at the DTHE (MateIS Laboratory, Lyon) the anatomy of three articulated skeletons from the Royal Belgian Institute of Natural Sciences collection: two specimens of Eurohippus messelensis, as well as the only accessible skeleton of Hallensia matthesi. The segmented 3D models allow us to visualize for the first time some cranial, dental and postcranial features that were previously concealed. Surprisingly, the tooth rows of the two specimens of E. messelensis show two different morphologies. One is typical of E. messelensis whereas the other shows all the diagnostic characters of E. parvulus expressed by Franzen (2006). However, based on the monograph on equoids from Messel by Franzen (2007), E. messelensis was only recognized in Messel, whereas E. parvulus was known from several other localities, notably in the Geiseltal, but not in Messel. We thus suggest that E. parvulus may have also been present in Messel, which raises the question of their potential synonymy. Finally, the preservation of the skeleton of Hallensia matthesi does not permit to observe the fine anatomy of the skeleton, but still permits to discuss important characters such as the number of fingers.
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RBINS Staff Publications 2025 OA
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Abc Taxa, Field guide to the brittle and basket stars (Echinodermata: ophiuroidea) of South Africa.
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Brittle and basket stars (ophiuroids) are one of five extant classes of the phylum Echinodermata and have a fossil record dating back almost 500 million years to the Early Ordovician. Today they remain diverse and widespread, with over 260 described genera and over 2 000 extant species globally, more than any other class of echinoderm. Ophiuroid species are found across all marine habitats from the intertidal shore to the abyss. In southern Africa, the ophiuroid fauna has been studied extensively by a number of authors and is relatively well-known. The last published review of the southern African Ophiuroidea however was by Clark and Courtman-Stock in 1976. It included 101 species reported from within the boundaries of South Africa. In the 40 years since that publication the number of species has risen to 136. This identification guide, which is the nineteenth volume of the series Abc Taxa includes a taxonomic key to all 136 species, and gives key references, distribution maps, diagnoses, scaled photographs (where possible), and a synthesis of known ecological and depth information for each. The guide is designed to be comprehensive, well-illustrated and easy to use for both naturalists and professional biologists. Taxonomic terms, morphological characteristics and technical expressions are defined and described in detail, with illustrations to clarify some aspects of the terminology. A checklist of all species in the region is also included, and indicates which species are endemic (33), for which we report significant range extensions (23), which have been recorded as new to the South African fauna (28) since the previous monograph of Clark and Courtman-Stock (1976) and which have undergone taxonomic revisions since that time (28). This contribution delivers a copiously illustrated overview of the volume and details how it has been diffused in South Africa and beyond.
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RBINS Staff Publications 2021
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Varanidé, Saniwa orsmaelensis, de l'Eocène basal du Nord-Ouest de l'Europe
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Saniwa est un genre éteint de lézard varanidé de l’Eocène européen et nord-américain et taxon frère du groupecouronne Varanus. Jusqu’à maintenant, seule une espèce, Saniwa orsmaelensis était rapportée en Europe, dans l’Eocène basal de Dormaal, Belgique. Cette espèce, originellement nommée par Louis Dollo il y a presqu’un siècle, est le plus ancien varanidé d’Europe. Malheureusement, le matériel diagnostique était limité à quelques vertèbres, décrites assez brièvement et non figurées, si l’on excepte une vertèbre dorsale désignée comme lectotype. Nous décrivons et illustrons ici de nouveaux spécimens de Dormaal ainsi que du Quesnoy, Bassin de Paris, France, incluant des restes crâniens (maxillaire, dentaires et pariétal), permettant de confirmer la validité de ce taxon européen. Ces nouveaux spécimens permettent en effet de nouvelles comparaisons avec l’espèce-type Saniwa ensidens, de l’Eocène moyen des formations de Bridger et de Green River, Wyoming, Etats-Unis et permettent d’amender la diagnose de S. orsmaelensis. La présence de S. orsmaelensis est restreinte à l’Eocène inférieur du Nord-Ouest de l’Europe et son origine géographique n’est pas encore certaine car Saniwa apparait simultanément en Amérique du Nord en Europe. La présence relativement brève des lézards varanidés dans le Paléogène Européen pourrait résulter des rapides changements environnementaux aux alentours du Paleocene Eocene Thermal Maximum qui ont permis de nombreux échanges fauniques dans l’hémisphère nord. Cependant, le sens de ces migrations n’est pas encore connu. Par ailleurs, les considérations paléogéographiques liées à la distribution du genre Saniwa suggèrent une origine asiatique bien qu’une origine africaine ne puisse être complètement exclue. Ce résumé est une contribution au projet réseau Belspo Brain BR/121/A3/PalEurAfrica financé par le Bureau de la Politique Scientifique Belge.
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RBINS Staff Publications 2019
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La locomotion des mésonychidés européens (Mesonychia, Mammalia): Born to run ?
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Les Mesonychia appartiennent à un groupe éteint de mammifères prédateurs à sabots. Diversifiés (plus de 20 genres actuellement répertoriés ; Szalay et Gould 1966 ; Rose 2006), ils sont connus dans l’ensemble de la Laurasia (Asie, Europe, Amérique du Nord), du Paléocène inférieur à l’Oligocène inférieur. Les Mesonychia sont séparés en deux familles : Hapalodectidae et Mesonychidae (Szalay et Gould 1966; Solé et al. 2018). Ces derniers ont connu deux événements radiatifs : au Paléocène, avec la diversification des clades de « Dissacus », et au début de l’Éocène, avec l’apparition de mésonychidés spécialisés regroupés, notamment, dans le clade Mesonyx (Solé et al., 2018). Les Mesonychidae étaient présents en Europe à partir du Paléocène supérieur (Thanétien) jusqu’à la fin de l’Éocène inférieur (Yprésien). Deux genres, « Dissacus » et Pachyaena, y ont été identifiés. Mis à part Pachyaena gigantea (Vaugirard, France, début de l’Yprésien) et « Dissacus » europaeus (Cernay et Berru, France, Thanétien tardif), décrits respectivement par Boule (1903) et Thewissen (1991), les mésonychidés européens ont été décrits à partir d’éléments dentaires. Cependant, ces dernières années, plusieurs éléments dentaires et postcrâniens ont été découverts dans les localités de l’Éocène inférieur de Palette (France ; MP7) et de La Borie (France ; MP8+9). Nous avons récemment étudié ces nouveaux restes, mais également révisé ceux du P. gigantea de Vaugirard, décrits mais uniquement partiellement représentés au début du 20ème siècle (Boule 1903). Leur description comparative permet de reconstruire l’évolution de la locomotion des mésonychidés européens et d’inclure ces nouvelles données morphologiques dans la matrice portant sur les parentés au sein des Mesonychia récemment améliorée par Solé et al. (2018). Les analyses phylogénétiques (en parcimonie standard et en bayésien « tip dating » mettent en évidence un clade regroupant la plupart des espèces européennes : ceci permet d’imaginer qu’un groupe de mésonychidés a évolué de manière endémique en Europe. Nous proposons de réutiliser un nom de genre proposé par Lemoine (1891) pour l’une des espèces de ce clade : Hyaenodictis. Il regroupe dorénavant cinq espèces auparavant référées au genre « Dissacus ». Concernant l’écologie, nous concluons que Hyaenodictis raslanloubatieri (La Borie) et Hyaenodictis rougierae (Palette) étaient dorsostables, digitigrades spécialisés et coureurs, alors que P. gigantea était plantigrade – bien qu’également coureur. Les différences de posture et de masse corporelle de ces deux genres reflètent une différence de niche écologique ne corroborant pas l’hypothèse selon laquelle Pachyaena aurait pu être remplacé écologiquement par Hyaenodictis au cours de l’Yprésien. Ce nouveau matériel postcrânien de mésonychidés européens permet de constater une convergence avec certains mésonychidés nord-américains appartenant au clade Mesonyx. Des similitudes morphologiques (e.g., disparition du foramen de l’astragale) liées à une même locomotion sont en effet observées sur les deux continents.
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RBINS Staff Publications 2019
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Apports de la chémostratigraphie "long-terme" (isotopes stables du carbone sur la matière organique) à la datation de mammifères durant le Paléogène
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Depuis quelques décennies, les rapides (« court-terme » - quelques dizaines à quelques centaines de milliers d’années) excursions d’isotopes stables (δ13C et δ18O) sur différents types de supports (roche totale carbonatée, nodules de paléosols, certaines espèces animales et végétales, matière organique totale ou spécifique) servent de jalons chémostratigraphiques éprouvés durant le Paléogène (Late Danian Event, PETM ou ETM-1, ETM-2, ETM-3, MECO, Oi-1, Oi-1a, etc). Récemment, les tendances isotopiques des mêmes éléments, utilisées à « long-terme » (quelques centaines de milliers d’années à quelques millions d’années) montrent une certaine utilité, particulièrement dans les coupes dépourvues d’autres informations stratigraphiques. Des coupes strictement continentales peuvent être ainsi corrélées avec les échelles chronostratigraphiques marines. A partir de plusieurs études de cas spécifiques au Maroc, Sud de la France (Corbières, Minervois, région de Montpellier, Provence), Angola et Belgique, la présente communication illustrera les contraintes, biais et perspectives de la chémostratigraphie (appelée également chimiostratigraphie) « long-terme » du carbone sur la matière organique totale. Des corrélations inter-régionales, voire inter-continentales (notamment avec le Wyoming, USA), sont mises en évidence en couplant bio- et chémo-stratigraphie, autorisant une discussion de l’évolution des mammifères dans différentes régions, y compris celles contenant des faunes strictement endémiques.
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RBINS Staff Publications 2019
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Five adjacent Aquifer Thermal Energy Storage (ATES) systems in Cenozoic and Paleozoic aquifers in Brussels: numerical simulation of their possible interactions
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RBINS Staff Publications 2023
