Inventory and preliminary study of Lutetian fossil mammals from the "Oberbuchsiten" collection of the Olten Museum of Nature: focus on perissodactyls

The locality of Oberbuchsiten, situated in close proximity to the renowned Middle Lutetian site of Egerkingen (Solothurn, Switzerland), hosts a diverse and extensive fossil mammal assemblage. A project to inventory and update the so far unpublished fossil collection from Oberbuchsiten at the Olten Museum of Nature (Solothurn, Switzerland) was carried out as part of the SwissCollNet project in collaboration with the JURASSICA Museum (Jura, Switzerland). This recent collection is of interest due to its provenance from the same karst fill, which renders it homogeneous in comparison to the oldest collections of Egerkingen/Oberbuchsiten for which the origin of a significant part remains uncertain. The collection found in the second part of the 19th century (Stehlin, 1903) is more homogeneous as it was referred to specific quarries or lenses (e.g. "St. Verena" quarry for a large part of Stehlin collection in NMB), nevertheless the evolution of the quarries during the last century makes it difficult nowadays to identify the specific fissure filling which provided this collection. The fauna of Oberbuchsiten at the Olten Museum of Nature is predominantly composed of paleotheres (Perissodactyla, Mammalia), whose abundance demonstrates a high degree of morphological and dietary diversity, indicating adaptation to multiple strata and ecological niches. The composition of the assemblage confirms the correlation with MP14 reference level and indicates a dense forest environment in a humid tropical to subtropical climate. Further study of this collection, alongside a comparison with other assemblages from Egerkingen/Oberbuchsiten, will confirm whether there are any significant differences that could be attributed to the “Oberbuchsiten” collection at the Museum of Olten Nature.