Gaël De Ploëg

Un gisement sparnacien exceptionnel à plantes, arthropodes et vertébrés (Éocène basal, MP7): Le Quesnoy (Oise, France)

A new fossil locality is reported from the argiles a lignite du Soisonnais (Early Ypresian, MP7) of the Oise region (France). After the preliminary survey of the flora and the vertebrate and arthropod faunas, we propose a reconstruction of a fluvio-lacustrine palaeoenvironment with a forest, under a warm and wet seasonal climate. This site is outstanding because of the richness, diversity and the state of preservation of the fossils. The present discovery opens a unique window on terrestrial life during the Earliest Eocene.

First Clarkforkian equivalent Land Mammal Age in the latest Paleocene basal Sparnacian facies of Europe: fauna, flora, paleoenvironment and (bio)stratigraphy.

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.

Extraction du pollen inclus dans l'ambre [Sparnacien du Quesnoy (Oise), bassin de Paris] : vers une nouvelle spécialité de la paléo-palynologie

Some amber fragments from Le Quesnoy (Oise) yield pollen, confined in this fossil resin. An extraction method has been devised in order to observe it under light and scanning electron microscopes. This method consists of a partial dissolution of the amber by organic solvents, which softens it and enables dissection of the fragments. The extracted pollen appears to be in an excellent state of preservation. The three-dimensional shape of the pollen grains is well preserved and their cell contents are still present. Thus, this method opens numerous study fields of this peculiar palynoflora. The diagnoses of the morphographic taxa observed, as well as their botanical relationships with modern taxa, can be re-examined. Other developments are explored, such as the study of the cell contents.Abstract Some amber fragments from Le Quesnoy (Oise) yield pollen, confined in this fossil resin. An extraction method has been devised in order to observe it under light and scanning electron microscopes. This method consists of a partial dissolution of the amber by organic solvents, which softens it and enables dissection of the fragments. The extracted pollen appears to be in an excellent state of preservation. The three-dimensional shape of the pollen grains is well preserved and their cell contents are still present. Thus, this method opens numerous study fields of this peculiar palynoflora. The diagnoses of the morphographic taxa observed, as well as their botanical relationships with modern taxa, can be re-examined. Other developments are explored, such as the study of the cell contents.

Le contenu cellulaire du pollen fossilisé dans l'ambre, préservé à l'état organique

The cell contents are still present inside almost every fossil pollen grain embedded in amber of two different origins (Lower Eocene amber from Paris Basin, Tertiary Baltic amber): they are here described after the observation of numerous extracted grains. Some structures are identified, among which probably the nucleus. Because of their confining in this very peculiar fossilization medium, the cell contents were not permineralized but remained somewhat close to the original organic condition, hence offering a field of research about fossil intracellular structure and palaeo-biochemistry, some organic molecules remaining potentially preserved.

Eosialis, a new alderfly genus in French Lowermost Eocene amber (Insecta, Megaloptera, Sialidae)

A new genus and species of Sialidae, Eosialis dorisi nov. gen., nov. sp. is described from the Lowermost Eocene amber of Oise (France). Its phylogenetic affinities within this family remain uncertain.

New fossil non−cyclostome braconid wasps from the lowermost Eocene amber of Paris Basin

Two braconid wasp taxa with enlarged eyes and ocelli indicative of probable nocturnal activity are discussed and described from the lowermost Eocene amber of the Paris Basin.The new tribe Palaeocharmontini nov., for new genus Palaeocharmon with type species Palaeocharmon basalis sp. nov. is described and illustrated in the subfamily Charmontinae. The similarity of this taxon with members of subfamilies Helconinae, Homolobinae, and Brachistinae is shown and the peculiar character [presence of hind wing recurrent vein (m-cu)] unknown previously in non-cyclostome braconids is discussed. A third fossil species of the genus Phanerotoma (Ph. menieri sp. nov.) is described and compared with known species from the Baltic amber.