New insights into the early evolution of horizontal spiral trace fossils and the age of the Brioverian series (Ediacaran-Cambrian) in Brittany, NW France

In northwestern France, the Brioverian series is a thick siliciclastic succession deposited during the Cadomian cycle (c. 750-540 Ma). In the uppermost Brioverian beds, previous studies unravelled an assemblage dominated by simple horizontal trace fossils associated with microbially stabilized surfaces. Here, we report Spirodesmos trace fossils - one-way, irregular and regular horizontal spirals - from Crozon (Finistère, Brittany), Montfort-sur-Meu and St-Gonlay (Ille-et-Vilaine, Brittany). After reviewing the literature on horizontal spiral trace fossils, an Ediacaran-Fortunian Spirodesmos pool is identified from marginal-marine to shelf settings, while an Ordovician-Recent trend formed in the deep-marine realm. These results suggest that an onshore-offshore migration in Spirodesmos took place during Ediacaran-Fortunian to Ordovician time, similar to what happened in graphoglyptids. In addition, the age of the uppermost Brioverian beds (Ediacaran or early Cambrian) is still a pending question. Here, we report two new U-Pb detrital zircon datings from sandstone samples in St-Gonlay, giving maximum deposition ages of 551 ± 7 Ma and 540 ± 5 Ma. Although these results do not discard an Ediacaran age for the uppermost Brioverian beds, a Fortunian age is envisioned because the new dating corroborates previous dating from Brittany, Mayenne and Normandy. However, the intervals of error of the radiometric dating, and the dominance of non-penetrative trace fossils associated with matgrounds (an ecology more typical of the Ediacaran Period), do not allow definitive conclusions on the age of the uppermost Brioverian beds

New sharks and rays from the Cenomanian and Turonian of Charentes, France

New or so far poorly known neoselachians from the Cenomanian and Turonian of SW France are described. The material studied herein comes from nine localities in the Charentes region, comprising palaeoenvironments ranging from coastal to open marine environments, and consists of two orectolobiforms, six lamniforms, and four rajiforms. The new taxa are Squalicorax coquandi sp. nov. and Roulletia bureaui gen. et sp. nov. within lamniforms, and Hamrabatis bernardezi sp. nov., Archingeayia sistaci gen. et sp. nov., and Engolismaia couillardi gen. et sp. nov. within rajiforms. New specimens of Odontaspis rochebrunei Sauvage, 1880 from the type area allow redescription of this taxon, assigned herein to the genus Cenocarcharias. Occurrences of Squalicorax baharijensis, S. cf. intermedius, and Archaeolamna sp., previously unrecorded from this region, and Almascyllium, a genus generally described from younger strata, are also noted, and improve knowledge of mid−Cretaceous selachian faunas from Western Europe

Thermal analysis of Cretaceous ambers from southern France

Thermal properties of French Cretaceous ambers were investigated and compared with other ambers from various sites of the world. The amber samples came from 10 different localities in southern France, in the Charentes, Languedoc, and Provence regions, ranging from Late Albian to Santonian in age. Thermo- gravimetric (TG) and Differential Thermogravimetric (DTG) profiles were obtained at heating rate of 10 K/min in air, starting from room temperature (20\ub0C) and reaching a maximum temperature of 700\ub0C. Elemental Analysis for total Carbon, Hydrogen, Nitrogen and Sulphur was also carried out. The TG combustion profile of the resins started after 200\ub0C and complete combustion took place near 600\ub0C. The DTG behaviour is characterized by a main exo- thermal peak situated between 394 and 420\ub0C, accompanied by minor peaks and shoulders. The increasing value of the main exothermal peak correlates well to the increase of the age of the specimens, with a significant correlation coefficient (r = 0.7721, p = 0.0089). A significant correlation (r = 0.6728, p = 0.0004) is also found with other samples of different age and origin. By con- sidering the whole pattern of DTG peaks, a possible fingerprinting model of the French ambers is evaluated by multivariate analysis. Cluster Analysis and Principal Component Analysis show the presence of several clusters, according to the geological age and possibly to the palaeobotanical origin. The elemental analysis is consistent with that of other Cretaceous samples from different sites of the world. Carbon and hydrogen are the main constituents (range 73-80% and 9.5-11.5% respectively). Sulphur is detected in small amounts (0.8-2.4%). Nitrogen is absent or appears as traces only (0-0.008%). Oxygen and other ele- ments range from 4.6 to 16.8%. No successful clustering was possible according to the elemental composition. Thermal analysis, completed with multivariate statistics, is a useful source of information also for French ambers, as a help for identification of the age, diagenetic processes and palaeobotanical origin

Schizopterid bugs (Insecta : Heteroptera) in mid-cretaceous ambers from France and Myanmar (burma)

International audienceBugs of two new genera and species are described as Buzinia couillardi and Tanaia burmitica. They are preserved in mid-Cretaceous amber from south-west France and northern Myanmar (Burma), respectively (c. 100 Ma). These are the first formally described fossils of the heteropteran family Schizopteridae. Both belong to the subfamily Hypselosomatinae and are very similar to the extant genus Hypselosoma Reuter, providing evidence for the antiquity and morphological stability of this small bug family and the infraorder Dipsocoromorpha. Given the putative ecology of the fossils, a discussion is provided on the French and Burmese amber forest ecosystems. The geological setting of La Buzinie, a new amber deposit in south-west France that yielded the two specimens of Buzinia couillardi, is outlined

Early human occupation of the Red Sea coast of Eritrea during the last interglacial

The geographical origin of modern humans is the subject of ongoing scientific debate. The 'multiregional evolution' hypothesis argues that modern humans evolved semi-independently in Europe, Asia and Africa between 100,000 and 40,000 years ago 1, whereas the 'out of Africa' hypothesis contends that modern humans evolved in Africa between 200 and 100 kyr ago, migrating to Eurasia at some later time(2). Direct palaeontological, archaeological and biological evidence is necessary to resolve this debate. Here we report the discovery of early Middle Stone Age artefacts in an emerged reef terrace on the Red Sea coast of Eritrea, which we date to the last interglacial (about 125 kyr ago) using U-Th mass spectrometry techniques on fossil corals. The geological setting of these artefacts shows that early humans occupied coastal areas and exploited near-shore marine food resources in East Africa by this time. Together with similar, tentatively dated discoveries from South Africa(3) this is the earliest well-dated evidence for human adaptation to a coastal marine environment, heralding an expansion in the range and complexity of human behaviour from one end of Africa to the other. This new, widespread adaptive strategy may, in part, signal the onset of modern human behaviour, which supports an African origin for modern humans by 125 kyr ago