Here we review the fossil record of European mesonychids, which are known only through the genera Dissacus and Pachyaena from Thanetian and Ypresian localities (from MP6 to MP10 reference-levels). We describe two new species, Dissacus rougierae, sp. nov., and Dissacus raslanloubatieri, sp. nov., respectively from Palette (Ypresian, ≈MP7) and from La Borie (Ypresian, ≈MP8 + 9). We also describe new specimens of D. europaeus from Berru (Thanetian, ≈MP6). The evolution of the geographic distribution of the European mesonychids is characterized by three phases: (1) the mesonychid Dissacus appeared in Europe during the Thanetian (≈ 57–58 Mya), probably due to dispersal from North America; D. europaeus survived the PETM event (≈ 56 Mya) and possibly experienced a dwarfism; (2) the large mesonychid Pachyaena migrated into Europe shortly after the Paleocene-Eocene boundary (≈ 55 Mya), but it was restricted to northwestern Europe, while Dissacus is recorded at this time only in southwestern Europe (Palette); and (3) Pachyaena rapidly disappeared from European environments, while Dissacus subsequently dispersed into northwestern Europe (≈ 54–52 Mya). We performed phylogenetic analyses in order to identify the relationships of the new species among mesonychids. It seems that the mesonychids went through two radiative events: the first during the Paleocene, the second mostly during the early Eocene. The first one corresponds to the diversification of Dissacus, while the latter resulted in the appearance of the most specialized mesonychids, such as Pachyaena and Mesonyx.
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RBINS Staff Publications 2017
The Democratic Republic of the Congo has the highest diversity of ant species in the Afrotropical region, even though it remains largely understudied in the modern era. The aim of this study is to report on an inventory of the litter ants from the Yangambi Biosphere Reserve in the Tshopo Province, north of the Congo River. Three habitats (fallow, secondary forest and primary forest) were sampled at six localities. A total of 190 ant species belonging to 50 genera and 8 subfamilies, have been recorded in the Yangambi biosphere region. Besides, 96 species were added to Tshopo Province, bringing the total to 306, a 44% increase; and we added 55 species to the already diverse Democratic Republic of the Congo, raising the total record to 791 species, a 7% increase. At least 10% of the collected species are new to science.
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RBINS Staff Publications 2025
