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International audience; Further to the work published by Néraudeau et al. six years ago, palynological matter recovered from the lignitic bone bed of Angeac in Charente (south-west France) has been re-examined in order to provide more evidence of its age, the previous Hauterivian–Barremian interpretation being regarded as controversial. The samples come from four sedimentological units, An2–An5, which together yielded an assemblage of 34 species, taxonomically dominated by palaeoecologically significant lygodiaceous verrucate spores, including eight species attributable to the genus Concavissimisporites and three species of Trilobosporites. A few bisaccate pollen grains, including Vitreisporites pallidus, have been recovered, but the gymnospermous pollen spectrum is clearly dominated by the cheirolepidiaceous genus Classopollis, its abundance diminishing progressively upwards from units An4 to An2. The great abundance and diversity of verrucate forms, along with the presence of other spores typical of Lower Cretaceous deposits, such as Aequitriradites verrucosus, and the scarcity of specimens referable to Cicatricosisporites, render this assemblage most similar to those of the Hastings Group of southern England, and the Bückeberg Formation in north-western Germany. The time of deposition is, therefore, more likely to have been Berriasian–Valanginian rather than Hauterivian–Barremian, as previously stated. The associated small assemblage of megaspores is consistent with this determination. Except for Trilobosporites and Concavissimisporites, the use of several other genera commonly applied to Mesozoic verrucate spores, such as Converrucosisporites and Impardecispora, is considered unnecessary. To support this assertion, a Principal Components Analysis has been carried out on 120 verrucate spores from sedimentological units An2–4, taking into account ten morphological variables. The results show that specimens attributable to Trilobosporites are well be separated from the main cluster, which corresponds to Concavissimisporites, underlining the futility of using more than two genera for the species concerned.

In order to improve our knowledge regarding the evolution of Lower Cretaceous plant paleoecosystems, being a fundamental period of their evolutionary history, here is presented the first bibliographical, paleoclimatic, palaeoenvironmental, stratigraphic, and taxonomic synthesis of continental palynological assemblages from French Lower Cretaceous deposits. This study is based on the observation of palynofloras recovered from 20 French sites (mostly Charentes, north of the Paris Basin, and subalpins massifs), and four sites from England, the age of deposits, mostly continental, ranging from Tithonian to Cenomanien. 446 palynological species were identified following the observation of 120 samples, mainly corresponding to spores and pollen grains, but algae and dinocysts were also recovered. A Morpho-statistical analysis of Lower Cretaceous verrucate spores was carried out in order to determine precisely the diagnostic features of the morpho-species, and improve their stratigraphic and palaeoenvironmental resolution in the long run. The palaeoenvironmental and paleoclimatic evolution inferred from palynological observations suggests the existence of arid to semi-arid climatic conditions between late Tithonien and mid-Berriasian (sebkhas-type environments), followed by an abrupt change marked by a pronounced humid phase during late Berriasien and earliest Valanginian, and by a progressive decrease of the humidity from the mid Valanginian to early Aptian (floodplains and humid forests-types environments). Albian and Cenomanian ages are characterized by generally humid conditions, thus less so than the humid phase associated with the late Berriasian (mangrove-type environments). Several aridification phases are noted between late Berriasian and late Albian : at the end of early Valanginian, between late Barremian and early Aptian (thus not very pronounced in northern France), and to a lesser extent during the mid Albian in northern France. Lower Cretaceous continental palynomorphs are rarely considered as strong briostratigraphic markers. Thus, two complementary dating methods have been developed herein, in order to facilitate the dating process of continental deposits. Their validity was tested using Lower Cretaceous continental assemblages from Purbeck and Wealden strata of England, and they were used to determine precisely the age of deposition of Angeac (Charente), and Pays de Bray (Normandie) strata., Afin d’améliorer les connaissances, jusqu’alors lacunaires en France, quant à l’évolution des paléoécosystèmes végétaux durant le Crétacé Inférieur, période fondamentale de leur histoire évolutive, il est ici proposé de dresser la première synthèse bibliographique, paléoenvironnementale, paléoclimatique, stratigraphique, et taxonomique des assemblages palynologiques continentaux du Crétacé Inférieur de France. Cette étude s’appuie sur l’analyse des palynoflores provenant de 20 sites français (principalement Charentes, nord du Bassin de Paris, et massifs subalpins), et de quatre sites d’Angleterre, dont l’âge des dépôts, pour la plupart continentaux, s’échelonne entre le Tithonien et le Cénomanien. L’observation de 120 échantillons a permis l’identification de 446 espèces correspondant principalement à des spores et à des grains de pollen, mais également à quelques kystes d’algues et de dinoflagellés. L’analyse morpho-statistique de spores verruquées rapprochées de la famille des Lygodiaceae, très abondantes au Crétacé Inférieur, a permis de caractériser plus précisément les caractères taxonomiques discriminants, dont l’application pourra, à terme, améliorer la résolution stratigraphique et paléoenvironnementale de ces espèces. L’évolution paléoenvironnementale et paléoclimatique inférée des observations palynologiques suggère l’existence de conditions arides à semi-arides durant la fin du Tithonien et le début du Berriasien (environnements de type sebkhas), suivies par un changement abrupt marqué par une phase humide prononcée au Berriasien supérieur et au Valanginien inférieur, puis par une diminution progressive de l’humidité du Valanginien moyen à l’Aptien (environnements de types plaines d’inondation, forêts humides). L’Albien et le Cénomanien sont caractérisés par un retour à des conditions généralement humides, cependant moins marquées qu’à la fin du Berriasien (environnements de types mangroves). Plusieurs phases d’aridification ont été notées entre le Berriasien supérieur et l’Albien supérieur : à la fin du Valanginien inférieur, au Barrémien supérieur/Aptien inférieur (généralisée à l’Europe de l’Ouest, mais peu marquée dans le nord de la France), et à moindre échelle durant l’Albien moyen au nord du Bassin de Paris. Les palynomorphes continentaux du Crétacé Inférieur n’étant pour la plupart pas considérés comme des marqueurs stratigraphiques fiables, deux méthodes de datation complémentaires s’appuyant uniquement sur les assemblages continentaux ont été développées, afin de faciliter la datation des dépôts continentaux. Leur validité a été testée sur des assemblages de référence d’Angleterre, et elles ont ainsi permis de préciser l’âge des dépôts d’Angeac (Charente) et du Pays de Bray (Normandie).

International audience; Further to the work published by Néraudeau et al. (2012), palynological matter recovered from the lignitic bone bed of Angeac (Charente, SW France) has been re-examined, an additional sample having been processed in order to provide more evidence of its age, the previous determination being regarded as controversial (Benoit et al., in press). The samples come from four sedimentological units (An2–An5), which together yielded an assemblage of 31 species, taxonomically dominated by verrucate spores, including Concavissimisporites montuosus, Concavissimisporites verrucosus, Trilobosporites apiverrucatus, Trilobosporites canadensis, Verrucosisporites major, and other taxa. The criteria for their identification commonly being regarded as problematic, a PCA has been carried out on 60 well-enough preserved specimens from the most productive unit An2, taking into account eight morphological variables. The results show one group consisting of specimens referred to Trilobosporites, and a second larger group comprising Concavissimisporites, Verrucosisporites, and various morphologically intermediate forms, thus underscoring the subjectivity of their generic and specific attributions. A few bisaccate pollen grains, including Vitreisporites pallidus, have been recovered, but the gymnospermous pollen spectrum is clearly dominated by the cheirolepidiaceous genus Classopollis, representing 60% of the total assemblage. This dominance, coupled with the great abundance of Trilobosporites and Concavissimisporites, along with the presence of other spores typical of Lower Cretaceous deposits, such as Aequitriradites spinulosus, renders this assemblage most similar to those of the Hastings Group of southern England, and the Bückeberg Formation in north-western Germany. The time of deposition is therefore more likely to be Berriasian–Valanginian than Hauterivian–Barremian, as previously stated (Néraudeau et al., 2012; Allain et al., 2014).Benoit, R-A., Néraudeau, D., Martín-Closas, C.,. A review of the Upper Jurassic-Lower Cretaceous charophytes from the northern Aquitain Basin. Cretaceous Research, in press.Allain, R., Vullo, R., Le Loeuff, J., Tournepiche, J.F., 2014. European ornithomimosaurs (Dinosauria, Theropoda): an undetected record. Geologica Acta 12(2), 127-135.Néraudeau, D., Allain, R., Ballèvre, M., Batten, D.J., Buffetaut, E., Colin, J.P., Dabard, M.P., Daviero-Gomez, V., El Albani, A., Gomez, B., Grosheny, D., Le Loeuff, J., Leprince, A., Martín-Closas, C., Masure, E., Mazin, J.-M., Philippe, M., Pouech, J., Tong, H., Tournepiche, J.F., Vullo, R., 2012. The Hauterivian–Barremian lignitic bone bed of Angeac (Charente, south-west France): stratigraphical, palaeobiological and palaeogeographical implications. Cretaceous Research 37, 1–14.