The biota of the Upper Cretaceous site of Lo Hueco (Cuenca, Spain)

The Late Cretaceous (Campanian-Maastrichtian) fossil site of Lo Hueco was recently discovered close to the village of Fuentes (Cuenca, Spain) during the cutting of a little hill for installation of the railway of the Madrid-Levante high-speed train. To date, it has yielded a rich collection of well-preserved Cretaceous macrofossils, including plants, invertebrates, and vertebrates. The recovered fossil assemblage is mainly composed of plants, molluscs (bivalves and gastropods), actinopterygians and teleosteans fishes, amphibians, panpleurodiran (bothremydids) and pancryptodiran turtles, squamate lizards, eusuchian crocodyliforms, rhabdodontid ornithopods, theropods (mainly dromaeosaurids), and titanosaur sauropods. This assemblage was deposited in a near-coast continental muddy floodplain crossed by distributary sandy channels, exposed intermittently to brackish or marine and freshwater flooding as well as to partial or total desiccation events.The Konzentrat-Lagerstatt of Lo Hueco constitutes a singular accumulation of fossils representing individuals of some particular lineages of continental tetrapods, especially titanosaurs, eusuchians and bothremydid turtles. In the case of the titanosaurs, the site has yielded multiple partial skeletons in anatomical connection or with a low dispersion of their skeletal elements. A combination of new taxa, new records of taxa previously known in the Iberian Peninsula, and relatively common taxa in the European record compose the Lo Hueco biota. The particular conditions of the fossil site of Lo Hueco and the preliminary results indicate that the analysis of the geological context, the floral and faunal content, and the taphonomical features of the site provide elements that will be especially useful for reassess the evolutionary history of some lineages of European Late Cretaceous reptiles.Peer reviewe

Adaptations xéromorphes chez des Gymnospermes du Mésozoïque. Une revue avec des implications paléoclimatiques

La cuticule des plantes s’est révélée être un proxy à haute résolution des paléo-variations de la pCO2. Toutefois, la gamme des adaptations xéromorphes est plus large chez les Gymnospermes mésozoïques que chez leurs représentants actuels et ceci pourrait expliquer les différences de DS et IS entre les différents taxa d’un même assemblage fossile. Quatre principales réponses adaptatives aux pertes hydriques sont connues : réduction du rayonnement solaire, des circulations d’air asséchantes, de l’évapotranspiration et piégeage de l’eau de surface. Nous suggérons de compléter les mesures de la densité et de l’indice stomatique par des observations qualitatives des adaptations des microstructures cuticulaires.Plant cuticles have proved to be a high-resolution proxy of palaeo- pCO2 variation. Mesozoic gymnosperms, however, show a wider range of xeromorphic adaptations than their living relatives, and these may explain stomatal density/stomatal index differences between taxa within the same fossil assemblage. Four main adaptive responses to water loss are pointed out: reduction of solar radiation, reduction of drought-air circulation, reduction of evapotranspiration, and trapping of surface external water. In conclusion, we recommend supplementing quantitative estimates of stomatal density and index by qualitative observations of cuticular adaptive macro- and microstructures.</p

The conifer Glenrosa falcata sp nov from the Lower Cretaceous of Spain and its palaeoecology

International audienceBased on short shoots and isolated leaves collected from the upper Barremian coaly clays of the La Huerguina Formation (Una-Las Hoyas basin, Iberian Ranges, Spain) a new species of the fossil conifer genus Glenrosa Watson et Fisher emend. Srinivasan is here described for the first time in Europe. Glenrosa falcata sp. nov. displays the characteristic stomatal crypts and papillae projecting into the crypt neck, however it is differentiated from other Glenrosa species by its falcate leaf morphology with a long free part (over 50% of the leaf length), an acute and recurved leaf tip and robust epidermal cell papillae. Based on comparisons with living angiosperms possessing stomatal crypts (Nerium Linnaeus (Apocynaceae) and Blossfeldia Werdermann (Cactaceae)) and an assessment of the palaeoenvironment we conclude that G. falcata was a xerophytic shrub, that grew on well drained substrates in a seasonally dry and warm climate and formed a minor part of a vegetation dominated by the Cheirolepid Frenelopsis (Schenk) emend. Watson. This habitat was alkaline and oligohaline and therefore expands the previously reported environmental tolerances of Glenrosa

CO2 and temperature decoupling at the million-year scale during the Cretaceous Greenhouse

International audienceCO2 is considered the main greenhouse gas involved in the current global warming and the primary driver of temperature throughout Earth's history. However, the soundness of this relationship across time scales and during different climate states of the Earth remains uncertain. Here we explore how CO2 and temperature are related in the framework of a Greenhouse climate state of the Earth. We reconstruct the long-term evolution of atmospheric CO2 concentration ( pCO(2)) throughout the Cretaceous from the carbon isotope compositions of the fossil conifer Frenelopsis. We show that pCO(2) was in the range of ca. 150-650 ppm during the Barremian-Santonian interval, far less than what is usually considered for the mid Cretaceous. Comparison with available temperature records suggest that although CO2 may have been a main driver of temperature and primary production at kyr or smaller scales, it was a long-term consequence of the climate-biological system, being decoupled or even showing inverse trends with temperature, at Myr scales. Our analysis indicates that the relationship between CO2 and temperature is time scale-dependent at least during Greenhouse climate states of the Earth and that primary productivity is a key factor to consider in both past and future analyses of the climate system

Leaf architecture and ecophysiology of an early basal eudicot from the Early Cretaceous of Spain

Iterophyllum lobatum gen. et sp. nov. is reported from the late Barremian lithographic limestones of Las Hoyas, Spain. It consists of a simple, petiolate leaf, with a pinnately lobed lamina. The dentate thickened margin bears chloranthoid-like glands at lobe apices and sinuses. The venation is pinnate and craspedodromous, with three discernible vein orders. Based on the low regularity of vein course and angles and the low leaf rank, such a venation pattern may represent an early evolved leaf archetype in early basal eudicots. An acropetal leaf development mode in I. lobatum is similar to that in several living Papaveraceae. The leaf architecture and ecophysiology, particularly the vein widths and the glands, indicate that I. lobatum leaves were aerial. The plant grew close to water in the wetland terrestrial ecosystem of Las Hoyas. Iterophyllum lobatum might have been an opportunist species in early ecological succession stages after wildfires

Diversity and histology of a plant litter bed from the Cenomanian of Archingeay-Les Nouillers (southwestern France

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Effects of chemical preparation protocols on delta C-13 values of plant fossil samples

International audienceFor over a half-century, studies of the stable carbon isotope compositions of plant fossils have provided noteworthy conclusions about the evolution of Earth climate. However, different preparation protocols were used prior to carbon isotope analysis of plant fossils and the accuracy of measured C-13/C-12 ratios may strongly depend on them. We have applied the most frequently used chemical preparation protocols to Frenelopsis leaves from four Cretaceous localities of Western Europe. Our results indicate that procedures to extract plant fossils from sediments are not adequate to retrieve the original plant delta C-13 values. The use of Schulze's reagent to bleach cuticles in paleobotany allows misleading delta C-13 values of specimens from a same locality with positive shifts of up to 13.6%. and increases intra-specimen and inter-specimen variances. Sample treatment involving HCI or HCl + HF gives consistent delta C-13 mean values for a same leaf and for leaves from a same sedimentary bed. However, although HF does not provide any advantage in removing potential contamination sources, it alters plant fossil tissues, slightly increasing the intra- and inter-leaf variances of delta C-13 values. Our results indicate that processing plant fossils with HCl only is the most accurate and conservative way to retrieve original delta C-13 values. (C) 2015 Elsevier B.V. All rights reserved

Inflorescences of Mauldinia sp. (Lauraceae) and associated fruits from the Cenomanian of Languedoc Roussillon, France

International audienceInflorescences of Mauldinia (Lauraceae) are described from the middle Cenomanian Pauletian facies of Gard, Languedoc-Roussillon, south-eastern France. This is the first record of the genus from this part of Europe. Mauldinia sp. is described based on peduncles and lateral units. Isolated, slender peduncles show spirally arranged scars or rarely attached lateral units. Isolated lateral units consist of cladode-like structures showing up to seven flower/fruit scars. Some isolated fruits were found associated with peduncles and lateral units. Fruits are ovoid fruits contain a single, elongated seed. The pericarp consists of epicarp, mesocarp and endocarp. The seed consists of two cotyledons containing well-developed reserve cells. Mauldinia sp. from Gard differs from known Mauldinia species by having longer internodes along the peduncle and by the shape of the lateral units. Sedimentological and palaeontological evidence suggests that Mauldinia sp. from Gard grew in a protected, littoral environment with limited marine influence. This report provides new information to the relatively poorly known Cretaceous record of angiosperms in France. The occurrence of Mauldinia in the lower Upper Cretaceous of Gard corroborates the widespread occurrence of the genus in marginal littoral environments during the mid-Cretaceous

Montsechia vidalii, an early aquatic angiosperm from the Barremian of Spain

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