Search results for " fossil"
showing 10 items of 85 documents
The emergence of lobsters: phylogenetic relationships, morphological evolution and divergence time comparisons of an ancient group (decapoda: achelat…
2014
Lobsters are a ubiquitous and economically important group of decapod crustaceans that include the infraorders Polychelida, Glypheidea, Astacidea and Achelata. They include familiar forms such as the spiny, slipper, clawed lobsters and crayfish and unfamiliar forms such as the deep-sea and "living fossil" species. The high degree of morphological diversity among these infraorders has led to a dynamic classification and conflicting hypotheses of evolutionary relationships. In this study, we estimated phylogenetic relationships among the major groups of all lobster families and 94% of the genera using six genes (mitochondrial and nuclear) and 195 morphological characters across 173 species of…
Trace and soft body fossils from the Pedroche Formation (Ovetian, Lower Cambrian of the Sierra de Córdoba, S Spain) and their relation to the Pedroch…
2006
The low Lower Cambrian rocks from the Sierra de Cordoba contain one of the best successions in Europe, which consists of well exposed mixed facies with abundant fossil assemblages showing long stratigraphical ranges throughout the Pedroche Formation. These assemblages include diverse Ovetian archaeocyaths, trilobites, small shelly fossils, calcimicrobes, trace fossils and stromatolites. Trace fossils are still poorly known, and thus they are the main objective of this work. Ichnological data are obtained from the Arroyo de Pedroche 1, Arroyo de Pedroche 2 and Puente de Hierro sections. Trace fossils include the ichnogenera Bergaueria, aff. Bilinichnus, Cochlichnus, aff. Cosmorhaphe?, Cylind…
Sedimentological implications of an unusual form of the trace fossil Rhizocorallium from the Lower Muschelkalk (Middle Triassic), S. Poland
2011
Specimens of the trace fossil Rhizocorallium isp. with retrusive limbs occur in 10–20-cm-thick composite beds: the bottom layers contain abundant Planolites and Thalassinoides trace fossils, and the top layers are built of horizontally bedded pelitic limestone and contain less bioturbational structures. The first specimens of Rhizocorallium isp. occur just 2–3 cm above the lower surfaces of the top layers. The horizontal protrusive sections are 1 cm high and 1 cm wide. At some sites, the horizontal tunnels end, and the limbs become first obliquely retrusive (45°) at a distance of 1.5–2.5 cm, and then vertically retrusive at a distance of 4–6 cm, or at once vertically retrusive at a similar …
Evaluation des impacts environnementaux des Techniques Culturales Sans Labour (TCSL) en France
2007
L’attrait des techniques culturales sans labour pour les agriculteurs français est croissant. Près du tiers des surfaces de grandes cultures est implanté avec ces techniques aujourd’hui, essentiellement pour des raisons d’organisation de chantier et de coût. Mais leur intérêt vis-à-vis de l’environnement, souvent mis en avant à l’étranger, est il confirmé dans les situations françaises ? Huit organismes de recherche et de développement se consacrent depuis deux ans à une vaste étude pour évaluer les impacts des techniques sans labour sur le sol, la biodiversité, l’eau, l’air et les ressources fossiles. Cette étude présente l’état de l’art, les avantages et les limites des Techniques cultura…
Early Cambrian origin of modern food webs: evidence from predator arrow worms.
2007
7 pages; International audience; Although palaeontological evidence from exceptional biota demonstrates the existence of diverse marine communities in the Early Cambrian (approx. 540-520 Myr ago), little is known concerning the functioning of the marine ecosystem, especially its trophic structure and the full range of ecological niches colonized by the fauna. The presence of a diverse zooplankton in Early Cambrian oceans is still an open issue. Here we provide compelling evidence that chaetognaths, an important element of modern zooplankton, were present in the Early Cambrian Chengjiang biota with morphologies almost identical to Recent forms. New information obtained from the lowermost Cam…
Palaeoenvironmental andstratigraphic aspects of animal traces and plant remains in Spanish Permian red beds (Peña Sagra, Cantabrian Mountains, Spain)
1997
Abstract Various vertebrate and invertebrate traces and plants remains have been discovered in the Permian of Pico Paraes (Cantabrian Mountains). They occur in the Sagra Formation, a 400 m thick unit consisting of a vertical alternation of channels with conglomeratic sandstones and fossiliferous red siltstones with a caliche horizon at the top. The most common trace is Hyloidichnus major which is attributed to approximately 50 cm long Captorhinomorphs. Other tracks provisionally assigned to Limnopus could also indicate the presence of Temnospondyls. The bedding planes with traces also show some tracks of Isopodichnus cf. minutus which is ascribed to small triopsid crustaceans. Like the foot…
Milano Parco Sud: L'Energia della Memoria
2007
Un'idea semplice e rivoluzionaria: riuscire a trasformare, in armonia con la tradizione, il “parco agricolo sud” di Milano. La proposta si sviluppa su più piani: restauro delle abitazioni e cascine del parco, lo fruttamento delle energie eco-compatibili (biomassa, energia solare e energia idraulica), e promozione del parco come meta turistica. Un lavoro simile è già in atto in diverse parti della regione Lombardia. L’area del parco del Ticino dopo due anni di lavoro è quasi tutta eco compatibile. Nella provincia di Cremona alcune aziende agricole hanno già iniziato a sviluppare e a monetizzare la biomassa.
Formation of high added value chemicals by photocatalytic treatment of biomass
2020
The depletion of fossil fuel requires the search for alternative renewable feedstock and environmentally friendly methods for the production of high value-added compounds and fuels. In this context, the efficient use of biomass has emerged as a significant research field as it represents an alternative green and renewable carbon source. Various technologies have been explored for this purpose and heterogeneous photocatalysis represents a valid alternative to the catalytic methods since it can be carried out under mild experimental conditions without the addition of harmful oxidizing agents. Different biomass components have been used as the starting materials, and many valuable chemicals h…
First record of Anisian deposits in the Betic External Zone of southern Spain and its paleogeographical implications
2023
In the External Zones of the Betic Cordillera (S Spain), upper Muschelkalk (Ladinian) facies have been known for decades; however, so far there is no stratigraphic record of Anisian deposits. In the present study, new biostratigraphic data from a carbonate succession in the easternmost Subbetic domain reveal a Pelsonian-Illyrian (Anisian) age. The nautiloids Germanonautilus salinarius and Germanonautilus saharonicus are documented for the first time in the Iberian Peninsula, and together with the brachiopod Tetractinella trigonella and the bivalves Neoschizodus orbicularis and Myophoria vulgaris they represent marker fossils of Anisian deposits previously described from many other basins, b…
Names for trace fossils: a uniform approach.
2006
The taxonomic treatment of trace fossils needs a uniform approach, independent of the ethologic groups concerned. To this aim, trace fossils are rigorously defined with regard to biological taxa and physical sedimentary structures. Potential ichnotaxobases are evaluated, with morphology resulting as the most important criterion. For trace fossils related to bioerosion and herbivory, substrate plays a key role, as well as composition for coprolites. Size, producer, age, facies and preservation are rejected as ichnotaxobases. Separate names for undertracks and other poorly preserved material should gradually be replaced by ichnotaxa based on well-preserved specimens. Recent traces may be iden…