Search results for "fossil"
showing 10 items of 412 documents
Maksimālas zarnelpošanas iespaids uz Misgurnus fossilis zarnas anatomiju: eksperimentāls gala zarnas respiratoriskas funkcijas pierādījums
1924
Atsevišķs iespiedums no: Latvijas Universitātes Raksti, IX. 1924. Kopsavilkums angļu valodā.
A Revised Timescale for Human Evolution Based on Ancient Mitochondrial Genomes
2013
Summary Background Recent analyses of de novo DNA mutations in modern humans have suggested a nuclear substitution rate that is approximately half that of previous estimates based on fossil calibration. This result has led to suggestions that major events in human evolution occurred far earlier than previously thought. Results Here, we use mitochondrial genome sequences from ten securely dated ancient modern humans spanning 40,000 years as calibration points for the mitochondrial clock, thus yielding a direct estimate of the mitochondrial substitution rate. Our clock yields mitochondrial divergence times that are in agreement with earlier estimates based on calibration points derived from e…
The Neanderthalian molar from Hunas, Germany
2005
Abstract In this paper, we present a well-preserved isolated human molar found in 1986 in the Hunas cave ruin, south-east Bavaria. The tooth was located at the bottom of layer F2, which belongs to a long stratigraphic sequence comprising faunal remains as well as archaeological levels (Mousterian). A stalagmite from layer P at the base of the stratigraphic sequence was recently dated to 79.373±8.237 ka (base) and 76.872±9.686 ka (tip) by TIMS-U/Th (Stanford University). We identified the tooth as a right (possibly third) mandibular molar. Characteristic parameters such as crown and root morphology, fissure pattern, enamel thickness, occlusal and interproximal wear, dental dimensions and ind…
New insights into non-avian dinosaur reproduction and their evolutionary and ecological implications: linking fossil evidence to allometries of extan…
2013
It has been hypothesized that a high reproductive output contributes to the unique gigantism in large dinosaur taxa. In order to infer more information on dinosaur reproduction, we established allometries between body mass and different reproductive traits (egg mass, clutch mass, annual clutch mass) for extant phylogenetic brackets (birds, crocodiles and tortoises) of extinct non-avian dinosaurs. Allometries were applied to nine non-avian dinosaur taxa (theropods, hadrosaurs, and sauropodomorphs) for which fossil estimates on relevant traits are currently available. We found that the reproductive traits of most dinosaurs conformed to similar-sized or scaled-up extant reptiles or birds. The …
Oldest Homo and Pliocene biogeography of the Malawi Rift
1993
The Malawi Rift and Pliocene palaeofaunas, which include a hominid mandible attributed to Homo rudolfensis, provide a biogeographical link between the better known Plio-Pleistocene faunal records of East and Southern Africa. The Malawi Rift is in a latitudinal position suitable for recording any hominid and faunal dispersion towards the Equator that was brought on by increased aridity of the Late Pliocene African landscape. The evidence suggests that Pliocene hominids originated in the eastern African tropical domain and dispersed to southern Africa only during more favourable ecological circumstances.
A renewable energy mix to supply small islands. A comparative study applied to Balearic Islands and Fiji
2019
Abstract Power plants supplied by renewables are expanding around the world, increasing the sustainability of the energy sector. In this context, small islands are heavily reliant on fossil fuels. However, this paper shows that the same problem can be found also in small islands belonging to developed countries. To increase the energy sustainability of small islands, the authors assembled a simplified mathematical approach to evaluate the potential electricity production, exploiting the local available energy sources: solar, wind and sea wave. The mathematical model requires few information in input, such as climatic data about the local energy sources and technical features on the selected…
The Energy Market Impact of Climate Change on Electricity Generation in Europe
2018
In this paper, the policy trend in Europe towards the emission reduction target in the energy sector, as planned from the Paris Agreement, is analyzed. Although renewable energy sources are improving their share, the large use of coal as primary fuel and the uncertainty about nuclear production makes the transition hard. It's well known that future emission patterns from energy generation influence the climate change trend, but as shown in the following, there is also a reverse interrelation, due to the different environmental conditions caused by climate change affecting all generation technologies. Furthermore, energy prices, which derive from this changed framework likewise will influenc…
The Gravettian occipital bone from the site of Malladetes (Barx, Valencia, Spain)
2002
Abstract The juvenile occipital bone from the site of Malladetes in Valencia (Spain) is described and compared with other European Pleistocene representatives of the genus Homo . This specimen derives from a Gravettian cultural context and has been AMS radiocarbon-dated to 25,120±240 years bp . As such, it provides evidence on early modern human anatomy from the Central Mediterranean region of the Iberian peninsula. The clear evidence for a late survival of Neandertals in southern Iberia, has led to considerable debate surrounding the biological and cultural interactions between these Pleistocene humans and their early modern human successors, and it is within this context that the Malladet…
Subfossil chironomid assemblages in deep, stratified European lakes: relationships with temperature, trophic state and oxygen
2010
Summary 1. The distributions of subfossil remains of chironomid larvae in 28 large, deep and stratified lakes in Europe were examined in surface sediments along a latitudinal transect ranging from northern Sweden to southern Italy. 2. Canonical correspondence analysis (CCA) showed that summer surface water and July air temperature, as well as total phosphorus (TP) concentrations, hypolimnetic oxygen availability and conductivity were statistically significant (P < 0.05) explanatory variables explaining between 11 and 14% of the variance in the chironomid data. 3. Owing to the spatial scale covered by our study, many environmental variables were covarying. Temperature, TP concentration and o…
Melastomeae come full circle: biogeographic reconstruction and molecular clock dating.
2001
Rhexia, with 11 species in the Coastal Plain province of North America, is the only temperate zone endemic of the tropical eudicot family Melastomataceae. It is a member of the only pantropical tribe of that family, Melastomeae. Based on the chloroplast gene ndhF, we use a fossil-calibrated molecular clock to address the question of the geographic origin and age of Rhexia. Sequences from 37 species in 21 genera representing the tribe's geographical range were analyzed together with five outgroups. To obtain better clade support, another chloroplast region, the rpl16 intron, was added for 24 of the species. Parsimony analysis of the combined data and maximum-likelihood analysis of ndhF alone…