Search results for "FOSS"
showing 10 items of 556 documents
Taphonomic and Sedimentary Factors in the Fossil Record of Mammals
1990
The composition of the fossil assemblages of mammals (MFA) is traditionally considered as being controlled by historical factors. Its variations are attributed to biochronological changes due to evolutionary process or to biogeographic changes due to geodynamic process. The different MFA are compared as sampling units of similar nature. The presence or absence of taxa and their relative abundance are used as biochronologic and biogeographic indicators, and the samples (MFA) are considered homologous, although they appear in a different sedimentological, taphonomical, or tectonic context.
The oldest fossil evidence of a dental lamina in sharks
2006
(2006). The oldest fossil evidence of a dental lamina in sharks. Journal of Vertebrate Paleontology: Vol. 26, No. 4, pp. 1002-1003.
The middle lower Cambrian (Ovetian)Lunagraulosn. gen. from Spain and the oldest trilobite records
2015
AbstractThe type material ofAgraulos antiquusSdzuy, 1961 from the La Herrería Formation, northern Spain, is revised together with additional material and included in the new genusLunagraulos. The stratigraphical range ofLunagraulos antiquus(Sdzuy, 1961) – occurring below that of the trilobite species of the generaLunolenus,MetadoxidesandDolerolenusin the type locality of Los Barrios de Luna in the province of León, northern Spain – and the accompanying ichnofossil assemblage demonstrate an Ovetian age (lower part of Cambrian Stage 3, currently being discussed by the International Subcommission on Cambrian Stratigraphy) for this species. Moreover, the trilobiteLunagraulos tamamensisn. gen. n…
New bradorid arthropods from the Lower Cambrian of Spain
2007
Lower Early Cambrian rocks of the Pedroche Formation in the Sierra de Cordoba consist of well-exposed mixed facies with abundant fossil assemblages showing long stratigraphical ranges. These assemblages include diverse Ovetian archaeocyaths, trilobites, small shelly fossils, calcimicrobia, trace fossils, and stromatolites. For the ostracod-like Cambriidae it is the first record from the Iberian Peninsula. Cordubiella pedrochensis n.gen. n.sp. comes from two sections of the lower Pedroche Formation: the Arroyo de Pedroche 1 sec- tion, and the Arroyo Pedroche 2 section. The material was collected in the zone of Lemdadella perejoni, of lower Ovetian age and below the Eoredlichia FAD. It supple…
Lower Ovetian (Lower Cambrian) trilobites and biostratigraphy of the Pedroche Formation (Sierra de Córdoba, southern Spain)
2005
The low Lower Cambrian rocks from the Sierra de Cordoba, which consist of well exposed mixed facies and abundant fossil assemblages showing long stratigraphic ranges throughout the Pedroche Formation, represent one of the best successions of this age in Europe. The fossil assemblages include diverse Ovetian archaeocyaths, trilobites, small shelly fossils, calcimicrobia, trace fossils and stromatolites. Trilobites are still poorly known, and thus they are the main objective of this work. The trilobites studied originate from three sections. At the Arroyo de Pedroche 1 section, cf. Bigotinella and Bigotina bivallata are replaced towards the top by Lemdadella linaresae, Lemdadella perejoni sp.…
Plant macrofossil, pollen and invertebrate analysis of a mid-14th century cesspit from medieval Riga, Latvia (the eastern Baltic): Taphonomy and indi…
2017
The paper presents the results of an integrated environmental analysis on the fill of an exceptionally well-preserved mid-14th century cesspit from the historic centre of Riga (Latvia, eastern Baltic). Palynological, plant macrofossils and invertebrate analysis yielded important new information about the use of plants by the indigenous community living within the medieval city, including their socio-economic status. The taphonomy of the botanical and invertebrate data is considered to largely reflect the input of undigested food waste and human faecal material with a subordinate component derived through the input of cereal waste-products. The results show that the diet of the indigenous co…
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…
Electronic structure of CuAlO2 and CuScO2 delafossites under pressure
2007
The electronic structure of CuAlO 2 and CuScO 2 delafossites is investigated by means of optical absorption measurements under pressure and ab initio band structure calculations. Measurements are carried out on CuAlO 2 monocrystals and pulsed laser deposited CuAlO 2 and CuScO 2 thin films up to 20 GPa. CuAlO 2 is an indirect semiconductor that is stable in the pressure range explored here. The pressure coefficients of the indirect and direct gaps are found to be 15 meV/GPa and 2 meV/GPa respectively. CuScO 2 is a direct semiconductor and the pressure coefficient of the excitonic peak energy is -5.5 meV/GPa. Two reversible phase transitions are observed in CuScO 2 . At 13 GPa the delafossite…
Structural evolution of theCuGaO2delafossite under high pressure
2004
We have performed pseudopotential calculations and x-ray-diffraction and x-ray-absorption measurements on the ${\mathrm{CuGaO}}_{2}$ delafossite under high pressure. We have completely characterized the structural behavior of the low pressure phase. We have found out that the a axis is more compressible than the c axis, and as a consequence the oxygen octahedra defined by the gallium environment tend to become more regular under high pressure. We have determined the internal parameter describing the oxygen position inside the unit cell, and seen that it is nearly constant when pressure is applied. We have observed an irreversible phase transition affecting the copper environment but not the…
Transition path to a dense efficient-packed post-delafossite phase. Crystal structure and evolution of the chemical bonding
2021
We are thankful for the financial support received from the Spanish Ministerio de Ciencia e Innovación and the Agencia Estatal de Investigación under national projects PGC2018-094417-B-I00 (co-financed by EU FEDER funds), MAT2016-75586-C4-1-P/2-P, FIS2017-83295-P, PID2019-106383GB-C41/C42 and RED2018- 102612-T (MALTA Consolider), and from Generalitat Valenciana under project PROMETEO/2018/123. D.S-P, A.O.R, and J.A.S acknowledge financial support of the Spanish MINECO for the RyC-2014-15643, RyC-2016-20301, and RyC-2015-17482 Ramón y Cajal Grants, respectively.