First Clarkforkian Equivalent Land Mammal Age in the Latest Paleocene Basal Sparnacian Facies of Europe: Fauna, Flora, Paleoenvironment and (Bio)stratigraphy

Thierry Smith (1) , Florence Quesnel (2, 3) , Gaël de Plöeg (4) , Dario de Franceschi (5) , Grégoire Metais (5) , Eric de Bast (1) , Floréal Solé (1) , Annelisse Folie (1) , Anaïs Boura (5) , Julien Claude (6) , Christian Dupuis (7) , Cyril Gagnaison (8) , Alina Iajovleva (9) , Jérémy Martin (10, 11) , François Maubert (12) , Judicaël Prieur (4) , Emile Roche (13) , Yves Storme (14) , Romain Thomas (5) , Haiyan Tong (15) , Johan Yans (14) , Eric Buffetaut (16)

1 Direction Ope'rationnelle Terre et Histoire de la Vie
2 BRGM - Bureau de Recherches Géologiques et Minières (BRGM)
3 ISTO - Institut des Sciences de la Terre d'Orléans - UMR7327
4 Centre Permanent d'Initiatives pour l'Environnement des Pays de l'Oise
5 CR2P - Centre de recherche sur la Paléobiodiversité et les Paléoenvironnements
6 UMR ISEM - Institut des Sciences de l'Evolution de Montpellier
7 Ge'ologie GFA
8 Institut Polytechnique LaSalle Beauvais
9 Geological Institute of the Russian Academy of Sciences
10 School of Earth Sciences [Bristol]
11 LGL-TPE - Laboratoire de Géologie de Lyon - Terre, Planètes, Environnement
12 Lafarge Granulats Seine Nord
13 Département de Géologie
14 Département de Géologie
15 Palaeontological Research and Education Centre
16 LGENS - Laboratoire de géologie de l'ENS

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.

Domains: Continental interfaces, environment; Global Changes

Thierry Smith, Florence Quesnel, Gaël de Plöeg, Dario de Franceschi, Grégoire Metais, et al.. First Clarkforkian Equivalent Land Mammal Age in the Latest Paleocene Basal Sparnacian Facies of Europe: Fauna, Flora, Paleoenvironment and (Bio)stratigraphy. PLoS ONE, 2014, 9 (1), pp.1-20. ⟨10.1371/journal.pone.0086229⟩. ⟨insu-00985646⟩