The Paleocene-Eocene Thermal Maximum (PETM) is correlated with the first occurrences of earliest modern mammals in the Northern Hemisphere. The latest Paleocene Clarkforkian North American Land Mammal Age, that has yielded rodents and carnivorans, is the only exception to this rule. However, until now no pre-PETM localities have yielded modern mammals in Europe or Asia. We report the first Clarkforkian equivalent Land Mammal Age in the latest Paleocene deposits of the basal Sparnacian facies at Rivecourt, in the north-central part of the Paris Basin. The new terrestrial vertebrate and macroflora assemblages are analyzed through a multidisciplinary study including sedimentologic, stratigraphic, isotopic, and palynological aspects in order to reconstruct the paleoenvironment and to evaluate biochronologic and paleogeographic implications. The mammals are moderately diverse and not abundant, contrary to turtles and champsosaurs. The macroflora is exceptional in preservation and diversity with numerous angiosperms represented by flowers, fruits, seeds and wood preserved as lignite material, revealing an abundance of Arecaceae, Betulaceae, Icacinaceae, Menispermaceae, Vitaceae and probably Cornaceae. Results indicate a Late Paleocene age based on carbon isotope data, palynology and vertebrate occurrences such as the choristoderan Champsosaurus, the arctocyonid Arctocyon, and the plesiadapid Plesiadapis tricuspidens. However, several mammal species compare better with the earliest Eocene. Among these, the particular louisinid Teilhardimys musculus, also recorded from the latest Paleocene of the Spanish Pyrenees, suggests a younger age than the typical MP6 reference level. Nevertheless, the most important aspect of the Rivecourt fauna is the presence of dental remains of a rodent and a ‘‘miacid’’ carnivoran, attesting to the presence of two modern mammalian orders in the latest Paleocene of Europe. Interestingly, these two groups are also the only modern groups recorded from the latest Paleocene of North America, making Rivecourt the first direct equivalent to the Clarkforkian Land Mammal Age outside of North America.
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Background In the Western Palaearctic, many species of Darwin wasps exhibit a form of diapause known as free-living adult diapause, similar to hibernation in certain beetle, bumblebee and butterfly species. This study provides a first comprehensive overview of all known hibernating species and aims to improve the current ecological knowledge. New information We reviewed 439 species, confirming free-living adult diapause in 340; 81 remain unverified and 18 are excluded, which have been incorrectly reported as hibernators in the past. The validated dataset includes 7443 records from 27567 specimens, spanning over 235 years of both published and unpublished observations. We report 29 species as hibernators for the first time. Amongst the records, 388 provide the first evidence of hibernation for a species in a given country, with 67 also representing the species' first national record. We highlight the value of field-based data and caution against relying solely on collection dates to study diapause. The observed variability in diapause strategies and hibernacula underscores the importance of nature management for biodiversity conservation, especially preservation of microhabitats.
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RBINS Staff Publications 2025
