The end-Cretaceous extinction triggered the collapse of ecosystems and a drastic turnover of mammalian communities. During the Mesozoic, mammals were ecologically diverse, but less than extant species. Modern ecological richness was established by the Eocene, but questions remain about the ecology of the first wave of mammals radiating after the extinction. Postcranial fossils are often used to determine locomotor behavior; however, the semicircular canals of the inner ear also represent a reliable proxy. These canals detect the angular acceleration of the head during locomotion and transmit neuronal signals to the brain to allow stabilization of the eyes and head. Accordingly, vestibular sensitivity to rapid rotational head movements is higher in species with a larger canal radius of curvature and more orthogonal canals. We used high-resolution computed tomography scanning to obtain inner ear virtual endocasts for 30 specimens. We supplemented these with data from the literature to construct a database of 79 fossils from the Jurassic to the Eocene and 262 extant mammals. We compared data on canal morphology and another lifestyle proxy, the size of the petrosal lobules, which have a role in maintaining eyes’ movements and position. We find that Paleocene mammals exhibited a lower average and more constricted range of Agility Indices (AI), a new measure of canal radius size relative to body size, compared to Mesozoic, Eocene and extant taxa. In the early Paleocene, body mass and canal radius increased, but the former outpaced the latter leading to an AI decline. Similarly, their petrosal lobules were relatively smaller on average compared to other temporal groups, which suggests less ability for fast movements. Additionally, Paleocene mammals had similar AIs to extant scansorial and terrestrial quadrupeds. In contrast, the lack of canal orthogonality change from the Mesozoic to the Paleocene indicates no trend toward lower vestibular sensitivity regardless of changes in body size. This result may reflect functional differences between canal orthogonality and radius size. Our results support previous work on tarsal morphology and locomotor behavior ancestral state reconstruction suggesting that ground dwelling mammals were more common than arboreal taxa during the Paleocene. Ultimately, this pattern may indicate that the collapse of forested environments immediately after extinction led to the preferential survivorship of more terrestrially adapted mammals. Funding Sources Marie Sklodowska-Curie Actions: IF, European Research Council StG, National Science Foundation, Belgian Science Policy Office, DMNS No Walls Community Initiative.
Located in
Library
/
RBINS Staff Publications 2022 OA
Arranged in strings, the plastic clay deposits from Andenne are fillings of cryptokarsts of white and colored clays associated with three layers of Dinantian Frasnian limestone oriented EW. Sands, brown coal and Tertiary (Neogene) clays have accumulated according to thekarstic dissolution forming a pocket of up to 100m deep. The sulphuric acid stemming from the oxidation of sulphides of brown coals is the main responsible for the formation of kaolinitic clays at the expense of clay minerals and the feldspathic sands. The circulation of water induced the leaching of the iron and their accumulation in certain horizons. White clays rich in alumina and of low iron and alkali content were the most looked for their refractory properties. Exploitedat first on surface then in subterranean galleries, the extraction reached its maximal development around the 19 and 20th centuries to stop definitively in 1970. The clay and the white sand were used in the industries of fire: glassware, crystal, metallurgy... and fed the pottery, brick, tile, earthenware factory, porcelain factories, pipe factory and the industrial refractories. The white clay first and then the final products have been exported since the Middle Ages in Holland, Germany and France, contributing to the international reputation of the clays from Andenne. Depressions generated by the subsidence as a consequence of the underground extractions form a string of pools and ponds, sources of biodiversity. Finally, the Ceramics Museum preserves the traces of this remarkable geological, mining, industrial and artistic with its outstanding collections of pottery, porcelain and pipes. Living museum holder of memory, it provides educational and cultural functions from its exhibitions.
Located in
Library
/
RBINS Staff Publications
