First partial cranium of Togocetus from Kpogamé (Togo) and the protocetid diversity in the Togolese phosphate basin

Earliest cetaceans (whales) originated from the early Eocene of Indo-Pakistan, but the group dispersed through most of the oceans of the planet by the late middle to late Eocene. This late Eocene global distribution indicates that important dispersal events took place during the middle Eocene (Lutetian), a globally undersampled time interval that is well documented in the Togolese phosphate series. We report here the first discovery of a partial cetacean cranium from middle Eocene deposits of Togo (West Africa). A 3D model of the cranium and teeth was reconstructed in order to reveal hidden anatomical features. The dental and cranial characteristics of the Togolese specimen recall those of protocetid taxa described in Africa, Asia, and North America, but also display significant differences. In particular, we show that the new specimen shares a number of morphological features with the Togolese taxon Togocetus. Such a hypothesis is further supported by a cladistic analysis including 45 taxa and 167 morphological characters, which recovers the new specimen close to Togocetus as the first offshoot of protocetids. Phylogenetic analysis including all the protocetids remains of Kpogamé confirms the singular diversity of the Togolese phosphate basin, and enables to examine potential connections with faunas from contemporaneous localities in Africa.     

Taphonomie des plantes et interprétations paléoécologiques. Une synthèse

The taphonomy is a powerful and requisite tool for environmental reconstructions of ancient plant communities. Necrobiotic processes, which lead to the production of plant fragments, inform us on fossil plant physiology. Among the processes that can be drawn from necrobiotic studies is the retention of leaf organs on plants, the relative quantity of pollen grains produced by different fossil species or the significance of wildfire dynamics in ancient plant communities. Biostratinomy examination is a fundamental tool for elucidating fossil plant habitats. Numerous experimental data allow paleobotanists for evaluating the role of transport in the origin of fossil assemblages. Autochthonous plant assemblages, which are characterised by the preservation of fossil rooting structures, are relatively rare in the nature. In consequence, the search for palaeoecological information from parautochthonous to allochthonous assemblages has been a priority in taphonomy. As a result, taphonomic models have been elaborated in well-known sedimentological contexts, such as small lacustrine deltas, which allow for the distinction between riparian or perideltaic plant remains. Lithospheric processes modify plant debris after burial. The differences in the degrees of transformations (or alterations) during the diagenesis provide for information about the original morphology and biochemical composition of the plant tissues, which are also paleoecologically useful. Thus, amber diagenesis modifies resin biochemistry into new molecules that are still informative from the chemotaxonomical point of view.     

Invertébrés remarquables du Callovien inférieur de la Voulte-sur-Rhône (Ardèche, France)Remarkable Invertebrates from the Lower Callovian of la Voulte-sur-Rhône (Ardèche, France)

Remarkable Invertebrates from the Lower Callovian of la Voulte-sur-Rhône (Ardèche, France). The four-excavating field expeditions from 1983 to 1986 led to collect a considerable amount of new data from this exceptional paleontological site, which was neglected, and unexplored for the essential, until now. This paper presents a synthesis of the main available results. For the first time, the succession of the lithofacies is precised from all preserved deposits thick about 12 m. These observations reveal, on the whole, a great homogeneity of lithologic, paleobiologic or taphonomic characteristics, which denote a rather great constancy of the global environmental conditions. The lithofacies are schistous marls revealing former uncemented paleosubstrates, with clay very dominating (montmorillonite for 60–70%, calcium carbonate, siderite and limonite for less than 30% or 40%). The faunas are nearly exclusively composed of pelagic, nectopelagic or mesopelagic organisms (swimming in full water or dependent on free algal environments); they include very few benthic organisms. The marine water depth in this area would be estimated to have reached roughly 200 m. The surface and middle water strata, where lived the major part of organisms, must have been usually agitated, well oxygenated and illuminated. At the opposite side, the bottom water must have been very quiet and anoxic, in aphotic zona, which is responsible for the soft tissue mineralisation.     

Occurrence of the Lower Cambrian anemone-style trace fossils in the Zabuk Formation (Mardin–Derik,SE Turkey)

The Zabuk Formation of the Derik Group exposed over much of south-eastern Turkey presents a succession composed of shallow marine and fluvial siliciclastic sedimentary rocks. The Lower Cambrian assemblages containing abundant anemone-style trace fossils are known from most major palaeocontinents such as Laurentia, Baltica, and Gondwana. These have possible affinities with semi-infaunal dwelling anemones on siliciclastic mid-latitude shelves of West Gondwana in early Fortunian deposits. Among them is Bergaueria, characterized by plug-shaped burrows as exemplified by Bergaueria perata, that is, a characteristic trace fossil of the Cambrian globally.     

Étude biostratigraphique et paléoenvironnementale des diatomées pyritisées de l'intervalle Paléocène supérieur-Éocène inférieur du sondage de Saint-Josse (France)

This paper presents the results of a biostratigraphic analysis of pyritized diatom assemblages in the Saint-Josse core (CC82) located in the northern part of the Paris basin (coordinates: X =555?000, Y =307?324 and Z =56.9 m). During the Paleocene-Eocene this locality was situated in a small bight of the North Sea Basin. The results are obtained from sediments of the Thanet and Mont-Bernon group equivalents belonging to the Paleocene-Eocene interval. Thirteen samples were studied and eleven contain pyritized diatoms. By epigenesis, the siliceous frustule of the diatom is changed into a pyritized skeleton with all the ornamentation very well preserved such as the velum, the areolae, the labiate processes, etc. Dispersive X-Ray analyses show this complete replacement of silica by pyrite. Another form of pyritization is crystallization of pyrite (in cubes, pyritohedrons, octahedrons, framboids) in internal cavities of the diatoms to produce internal moulds, also called steinkerns, which preserve the external morphology of the diatoms and some details such as the girdle. Despite pyritization, diatoms can often be recognized at the species level; brackish and marine species were observed but no fresh water specimens were encountered. Pyrite is easily altered into iron oxides. In outcrops, pyritized diatoms can be obscured or destroyed by oxidation. We have chosen borehole samples for this study to avoid the affects of weathering. Deposits from the Sorrus Unit (of the Thanet Group) have low abundances of pyritized diatoms (3 to 25 specimens per sample). This unit contains allochtonous diatom assemblages comprising Actinoptychussenarius, Coscinodiscus morsianus var. morsianus, and Coscinodiscus morsianus var. moelleri. Sample 34.31-34.45 from this unit is particularly interesting. It contains three specimens of Paralia siberica var. laevis, which is typical of an estuarine or littoral paleoenvironment, and corresponds to the more continental deposit of the Sorrus Unit. Seven samples, taken in the Argile de Saint-Aubin Unit (from the Mont-Bernon Group), contain more than 200 pyritized diatoms and between 9 to 16 different species per sample. A brackish assemblage (Actinoptychus senarius, Coscinodiscus commutatus and Stellarima microtrias) and a marine assemblage (C. morsianus var. morsianus, Coscinodiscus var. moelleri, Fenestrella antiqua, Odontellaheibergii, Rhizosolenia sp. 1 and Trinacria regina) are observed. The brackish assemblage expands in the upper part of the Saint-Aubin Unit indicating more widespread brackish paleoenvironmental conditions. Pyritized diatoms are important fossil markers in the Paris basin mainly when siliceous fossils (silicoflagellates or radiolarians) and others microfossils (foraminifers and dinoflagellates) are very poor or absent. Two diatom assemblages have been identified in the Saint-Josse borehole. The first assemblage D1, comprising C. morsianus var. moelleri (high occurrence), C. morsianus (a few) and T. regina (rare), is recorded in the Sorrus, La Calotterie, Bois Gorguette, Le Goulet and lower Saint-Aubin Units. The second assemblage D2, characterized by great abundance of F. antiqua and decreasing numbers of C. morsianus species, is found in the upper part of the Saint-Aubin Unit. These diatom assemblages can be correlated with other biozonations established in the North Sea basin and based on nannoplankton and diatoms (King, 1983), diatoms (Mitlehner, 1996) and calcareous nannoplankton (Martini, 1971). F. antiqua and C. morsianus var. moelleri are the more important diatom species encountered. F. antiqua (previously named Coscinodiscus sp. 1, King, 1983) is the fossil marker used by King to define his NSP4 biozone. The base of NSP4 corresponds to the lowest occurrence of F. antiqua and the top is marked by the highest occurrence of this species. The Sorrus, La Calotterie, Bois Gorguette, Le Goulet and Saint-Aubin (“Sparnacian” stage) Units, the last one comprising F. antiqua (increasing to acme), correspond to the NSP4 zone of King (1983). The Mont-Hulin and Château de la Bruyère Units correspond probably to the NSP5 zone of King (1983). F. antiqua and C. morsianus var. moelleri were also used by Mitlehner (1996) to differentiate the NSP4a zone (low abundance of F. antiqua and abundance of C. morsianus var. moelleri) from the NSP4b zone (great abundance and acme of F. antiqua). The abundance of C. morsianus var. moelleri is recorded in the lower part of Saint-Aubin Unit and the abundance of F. antiqua (high peak at 46% in the sample 17.87) is found in the upper part of Saint-Aubin Unit. Therefore, Sorrus, La Calotterie, Bois Gorguette, Le Goulet and the lower part of Saint-Aubin Units are correlated with the NSP4a zone and the upper part of Saint-Aubin Unit with the NSP4b zone. By correlating the calcareous nannoplankton biozonation (NP) of Martini (1971) with the biozonation of King (1983), adapted by Mitlehner (1996), the boundary between the NP9 and NP10 zones could be located in the 18.75-17.87 interval and the NP10-NP11 boundary at the top of Saint-Aubin Unit. Lithostratigraphic correlations between the units of the Saint-Josse borehole (Paris basin) and the formations of the North Sea basin can be established. The great abundance of C. morsianus var. moelleri and the great abundance (including acme) of F. antiqua are respectively recorded in the Sele and Balder Formations. Therefore, the interval Sorrus/lower Saint-Aubin Units is correlated with the Sele Formation and upper part of Saint-Aubin Unit with the Balder Formation.     

The La Voulte-sur-Rhône Lagerstätte (Middle Jurassic,France)

The La Voulte Lagerstätte (Jurassic, France) is characterized by a diverse and exceptionally well-preserved fauna. It was located along the western Tethyan margin where the submarine relief was steep. The sedimentation was dominated by marls suggesting a low energy and deep-water depositional environment. The La Voulte biota is remarkable for its biodiversity with about 60 different species. The major components are the arthropods (50% of the species), the cephalopods (10%) and the echinoderms (10%). Among the arthropods, the composition and some anatomical features suggest a relatively deep-water environment characterized by dim-light conditions. The cephalopods and other organisms (pycnogonids, asterids), have extant analogues that all live in deep-water niches always exceeding 200 m. The fauna as a whole bears the characteristic features of the present-day bathyal fauna. The La Voulte Lagerstätte may be one of the rare Jurassic Lagerstätten, if not the unique, to have fossilized a deep marine fauna.     

Un nouveau gisement à ambre insectifère et à végétaux (Albien terminal probable) : Archingeay (Charente-Maritime, France)

A layer of clay interbedded in sandstone, which age is likely uppermost Albian, yielded a new deposit with amber and fossil plants in Charente-Maritime (south-west France). A survey of the arthropods found in amber, the xylologic and palynologic determinations and the sedimentologic study are in progress. We already have datas to propose a palaeoenvironmental reconstruction of the coast of the northern Aquitain basin at the end of lower Cretaceous : an estuarine area under warm and wet climate.     

New data on the Dyrosauridae (Crocodylomorpha) from the Paleocene of Togo

Following our fieldwork in Paleogene deposits of Togo, we herein report cranial as well as postcranial elements belonging to the family Dyrosauridae. This assemblage is dated to the Late Paleocene (Thanetian) from two quarries in southern Togo. The specimens include a partial skull presenting two large supratemporal fossae and a massive occipital condyle; long and slender isolated teeth; amphicoelous vertebrae including several articulated ones; and two osteoderms devoid of carina. The morphology of the partial skull reveals similarities with some African longirostrine forms such as Rhabdognathus spp., although this attribution cannot be confirmed. Longirostrine forms, known in the late Paleocene and early Eocene of the Iullemmeden basin (Nigeria, Niger, Mali, Algeria) and in the phosphates of Morocco and Tunisia, is only represented in Thanetian levels in Togo. Different palaeoenvironmental settings seem to have characterized the various African basins during the lower Eocene, with consequences for the geographic distribution of dyrosaurids. These dyrosaurid remains confirm the presence of the family in Togo during the Paleocene and underline the fossiliferous potential of the coastal sedimentary basin in Togo and in the bay of Benin.     

Utilisation du bois de feu par les chasseurs-cueilleurs de la « Cidade de Pedra » à partir de l’Holocène moyen (Brésil Central,Mato Grosso,Rondonópolis)

Located in the south-western Mato Grosso state (Central Brazil), the vast territory of the Cidade de Pedra was continuously occupied since the mid-Holocene by several groups of hunter-gatherers. Rock paintings, lithic industries, ceramics, ornaments, combustion remains (etc.) testify their passages in the many rock art sites discovered since 1983. In this paper are presented the results of the first anthracological analyzes conducted in four of these rock shelters. The studies were realized from macro-remains carbonized from hearths, embers and concentrations. From the taxonomic identification of charcoal, the objectives are to highlight the practices of hunter-gatherers related to the collection of wood and the environment in which they evolved for nearly 5000 years. The results indicate that they practiced an opportunistic collection mainly focused on dry wood available in the vegetation around the sites. They evolved in an environment similar to that currently characterizes the region, a typical flora of the Cerrado Biome and seasonal climate.