Denise Pons

Signification des caractères partagés entre Bennettitales et Cycadales. Implications de la découverte d'une Cycadale nouvelle du Cénomanien de l'Anjou (France)

Abstract The lagoonal Cenomanian formation (Lower Cretaceous) of clays of the region of Baugeois (north of Angers) has supplied an exceptionally well-preserved fossil flora: leaves, woody structures or/and reproductive organs of pteridophyta, gymnosperms and angiosperms. A well-preserved fossil plant found in a quarry “Le Brouillard” (8 km from Angers), has allowed a detailed morphological and structural study of this species. A comparative study with extant plants has confirmed an undoubted link between the contemporary genus Dioon (an endemic cycad from Mexico) and the fossil species. However, features observed on the lower epidermis of the leaflets, present a similarity with some Jurassic Bennettitales. This discovery, added to other common features shared by these two orders, raises questions about their relationships, thought to be different from a phylogenetic viewpoint.

Distribution and paleoecology of freshwater algae and stromatolites: IV, some examples from the Tertiary of the Parisian Basin and the Alsace Graben (France)

Abstract In the Tertiary deposits of the Parisian Basin and the Alsace Graben, many encrusting spring deposits and shallow lakes revealed remains of algae and stromatolites. Among the 15 species encountered, 5 are new. One of them belongs to a new genus ( Gallella ) and a new group, that of algae with pseudoparenchym.

Singular taphonomic record of a wildfire event from middle Albian deposits of Escucha Formation in northeastern of Spain

A fossil plant assemblage composed of a great amount of macro, meso and microscopical charcoalifed remains occur in a single layer in Albian deposits of the Escucha Formation in northeastern Spain. This assemblage consists fundamentally of fragments of pinnae and pinnules corresponding to the Matoniaceous ferns Weichselia reticulata and Phlebopteris dunkeri also with some gymnosperm wood remains. The features of both the fossil plants and the deposit itself indicate accurate paleoenvironmental conditions related to the action of wildfires over the vegetation growing in freshwater swamp plains during Albian in Southwestern Eurasia.

Paleoenvironmental reconstruction of an Albian plant community from the Ariño bonebed layer (Iberian Chain, NE Spain)

The AR-1 layer, corresponding to the Escucha Formation (Lower Cretaceous) in the Santa Maria Mine of Ariño, has supplied rich and well-preserved macrofloral and palynological assemblages showing interesting data about both taphonomic and environmental conditions. This single layer is located in the Oliete Sub-Basin from the Maestrazgo Basin in northeastern Spain, and it represents one of the most outstanding single layer fossil sites in the world. This site shows abundant and diverse fauna containing exquisitely preserved vertebrate and invertebrate fossils (dinosaur bones, turtles, crocodiles, fishes, molluscs and ostracods) and also plant remains of Albian age. The assemblage is especially significant for dinosaur phylogenetic analysis. The sedimentary environment corresponds to a freshwater swamp plain with sporadic marine inputs within a deltaic–estuarine system under subtropical–tropical climate.

Palaeobotanical remains associated with dinosaur fossils from the Camarillas Formation (Barremian) of Galve (Teruel, Spain)

A well-preserved macroflora and rich palynological assemblages corresponding to the Camarillas Formation (early-middle Barremian) in the San Cristóbal and Galve Mine sites from the Galve sub-basin in northeastern Spain are presented here. These remains represent the first fossil plant evidence from these deposits. Within plant macroremains, the cheirolepidiacean Pseudofrenelopsis aff. varians (Fontaine) Watson has been found. The palynological assemblage yielded well-preserved spores and pollen grains, mainly dominated by the genus Classopollis. Spores are also abundantly represented by schizaeacean spores (Cicatricosisporites and Plicatella). This spore assemblage supports an early-middle Barremian age for these localities. It is noteworthy that small basal angiosperm pollen grains of the genera Crassipollis and Retimonocolpites, together with other indeterminate grains, have been reported here. This flora constitutes the primary food producer for dinosaur at that time, and thus the information of the flora is important for the understanding of the ecological background for the dinosaur evolution during the Early Cretaceous.

Lower Cretaceous (upper Barremian-lower Aptian?) palynoflora from the Kitadani Formation (Tetori Group, Inner Zone of central Japan)

Abstract The Tetori Group, which crops out in the Inner Zone of central Japan, has been extensively studied for its rich floral and vertebrate fossil assemblages. The authors provide the first contribution to the palynoflora of the Kitadani Formation, which has been dated as late Barremian to early Aptian on the basis of the freshwater bivalves recorded from it. The studied assemblage yields 45 genera and 41 species of spores and gymnosperm pollen grains, some freshwater algae, one epiphyllous fungus, and various plant fragments. No angiosperm pollen grains were observed. Some forms described here in detail are not yet known from the literature. They probably correspond to new species, but the scarcity of the specimens has caused us to place them temporarily in open nomenclature. This palynological study adds new data to the present knowledge on the Barremian-Aptian Tetori-type Paleoflora of eastern Asia. The authors compare the palynological inventory with recently published data obtained from the Barremian strata of the Choshi Group, the Outer Zone of Southwest Japan. Then, they situate the results among the previous paleoenvironmental reconstructions of the Tamodani Flora, and confirm a warm temperate and moderately humid climate, with locally drier conditions. Even if some elements of the assemblage suggest transportation, all of them are of continental origin and confirm a fluvio-lacustrine environment for the deposition.

Barremian palynofloras from the Ashikajima and Kimigahama formations (Choshi Group, Outer Zone of south-west Japan)

ABSTRACT The Choshi Group, which crops out in the Outer Zone of south-west Japan, has been extensively studied for its rich macroflora by Makoto and Harufumi Nishida, among others, and was attributed to the Ryoseki-type Floristic Province by Kimura (1987). New microfloras were discovered in muddy, very fine-grained sandstones and mudstones of the marine Ashikajima and Kimigahama formations, representing the base of the Choshi Group. The authors provide a palynological inventory for these lithological units, which have been dated as Barremian on the basis of the ammonites recorded from them, and compare them with the paleofloristic associations of the South-Laurasian Province (Brenner 1976) and Euro-Sinian Region (Vakhrameev 1991). The studied assemblages yielded 53 genera and 89 species of spores and gymnosperm pollen grains, and also marine or freshwater algae and some epiphyllous fungi. No angiosperm pollen grain was observed. Four new species are described: Manumia japonica n. sp., Foveosporites ryosekiensis n. sp., Nodosisporites choshiensis n. sp. and N. makotoi n. sp. Other forms, probably new species, are described here in detail, but the scarcity of the specimens has led us to place them temporarily in open nomenclature. The spatio-temporal distributions of the genus Manumia Pocock, reported for the first time in Asia, and Cicatricosisporites sinuosus Hunt, 1985 are plotted on paleogeographical maps. With this palynological study, we add new data to the present knowledge of Barremian floras. This assemblage probably corresponds to a taphocenose. The authors suggest that the climate indicated had marked dry and more humid seasons, in accordance with the hypothesis of a moderate migration of the oceanic islands of the Outer Zone before their collision with the Eurasian continent, or moderate climatic change during the Early Cretaceous in Japan.

New reconstruction of Weichselia reticulata (Stokes et Webb) Fontaine in Ward emend. Alvin, 1971 based on fertile remains from the middle Albian of Spain

Exceptionally well-preserved specimens from the middle Albian of Spain corresponding to a nearly complete fertile frond and fragments of pinnae containing soral clusters of the tree fern Weichselia reticulata have provided new data about the structure and arrangement of pinnae and their associated fertile reproductive structure. This new material has been compared with the previous studies, and recostructions of this fern and the new data indicate the segregation of vegetative and fertile fronds within the main stipe of this fern.