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
Micrometeorites are dust-sized (i.e., 10 to 2000 µm in size) extraterrestrial particles reaching the Earth’s surface [1]. We report the discovery of hundreds of micrometeorites during the 2017-2018 BELAM (Belgian Antarctic Meteorites) expedition that took place in the south to south-east area up to 40 km away from the Belgian Princess Elisabeth Station (71°57Ļ00ļS; 23°20Ļ49ļE). Two types of micrometeorite traps were targeted on the glacially eroded tops of Vengen, Walnumfjellet, Widerøfjellet, Svindland and Smalegga Mountains, consisting of 1/ seven samples of soils that have potentially been exposed for long periods of times (up to several Ma), similarly to samples collected in the Atacama Desert [2] and 2/ five samples of wind catchment areas, such as the base of large boulders or within cracks. The lee-sides of three lateral and supraglacial moraines were also sampled, totalling eleven samples. In all cases, the sampled material, weighing 80 kg, consisted of moderately sorted finegrained rock detritus. Preliminary results suggest that the distribution of micrometeorites varies according to the type of trap, with glacial moraines exhibiting the lowest concentrations, followed by wind-catchment areas and soils from the top of the glacially eroded summits of mountains. Samples exposed on the border of the Sør Rondane Mountains with the Antarctic Plateau exhibit concentrations one order of magnitude greater than in moraines. Similarly to the Larkman Nunatak micrometeorite collection [3], the micrometeorite accumulation mechanism in moraine and wind-catchment areas seems to be mainly controlled by wind. Conversely, direct infall of micrometeorites may contribute significantly as an accumulation mechanism in exposed soil samples, as evidenced by the presence of large micrometeorites (>400 µm in size). Thus, this new collection, comprising various sampling site types, may serve as the basis to understand micrometeorite distribution patterns in Antarctica.
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RBINS Staff Publications 2018
