Search results for "Ala"
showing 10 items of 18976 documents
Isotopic seawater temperatures in the Albian Gault Clay of the Boulonnais (Paris Basin): Palaeoenvironmental implications
2016
13 pages; International audience; Oxygen isotopes were measured on several types of fossil hardparts from the Gault Clay Formation including benthic and planktonic foraminifera, belemnite guards, and fish small-teeth. Belemnites δ18O values indicate low temperatures (13.5–19.3 °C) with an increase from the Middle to Late Albian. Foraminifera provide variable δ18O values, some too low to be relevant in terms of temperature (until 42 °C). These low values probably result from a diagenetic alteration of the foraminiferal tests even though SEM observations revealed well-preserved microstructures. However, higher foraminiferal δ18O values recorded in some levels indicate temperatures in the rang…
Reprint of "Shell oxygen isotope values and sclerochronology of the limpet "Patella vulgata" Linnaeus 1758 from northern Iberia: Implications for the…
2017
Abstract: Understanding environmental conditions faced by hunter-fisher-gatherers during the Pleistocene and Holocene, and interpretation of subsistence strategies, social organisation and settlement patterns, are key topics for the study of past human societies. In this respect, oxygen isotope values (?18O) of mollusc shell calcium carbonate can provide important information on palaeoclimate and the seasonality of shell collection at archaeological sites. In this paper, we tested P. vulgata shells from northern Iberia as a paleoclimate archive through the study of shell oxygen isotope values and sclerochronology of modern samples. Results showed that limpets formed their shells close to is…
Systematic review of the effects of chemical insecticides on four common butterfly families
2017
Safeguarding crop productivity by protecting crops from pest attacks entails the wide use of plant protection products that provide a quick, easy and cheap solution. The objective of this study is to understand the effects of insecticides used in agriculture on non-target butterflies, specifically on the families Lycaenidae, Nymphalidae, Hesperiidae, and Papilionidae. To achieve this goal, a formal systematic review was performed according to European Food Safety Authority (EFSA) guidelines, by entering a combination of keywords on 3 online databases. Three reviewers independently extracted information on study characteristics and quality. The main results were collected and grouped by the …
An invasive species, Carassius gibelio, alters the native fish community through trophic niche competition
2019
Carbon and nitrogen stable isotope analyses were used to determine isotopic niche width of the invasive fish species Carassius gibelio to help assess the niche overlap and potential impact of this species on the native fish fauna in the Karamenderes River, northwest Turkey. C. gibelio had the highest niche area of the coexisting species. The greatest overlap of isotopic niche was between C. gibelio and Mugil cephalus in the river mouth. The freshwater species displayed similar patterns when taking into consideration their relative abundance and isotopic overlap. While C. gibelio is likely to outcompete some species at some localities, the species was found co-occurring with others by maximu…
Cod at drift in the North Sea
2018
Abstract There has been a large-scale geographical re-distribution of the North Sea cod stock over the past century, and recent surveys indicate a north-eastern modal distribution. Here we assess the consequences of the contemporary distribution of North Sea cod (Gadus morhua) spawning biomass to inter-ocean recruitment potential. By simulations of drifting cod eggs and larvae spawned in the northern North Sea over 16 spawning seasons (in the period 1995–2016), we show that a large portion of the North Sea produced pelagic juveniles most likely settle along the Norwegian Sea shelf. For example during the early 2000s when the North Sea cod spawning biomass was at its lowest, 20% to 27% of la…
Growth patterns and life-history strategies in Placodontia (Diapsida: Sauropterygia)
2015
Placodontia is a clade of durophagous, near shore marine reptiles from Triassic sediments of modern-day Europe, Middle East and China. Although much is known about their primary anatomy and palaeoecology, relatively little has been published regarding their life history, i.e. ageing, maturation and growth. Here, growth records derived from long bone histological data of placodont individuals are described and modelled to assess placodont growth and life-history strategies. Growth modelling methods are used to confirm traits documented in the growth record (age at onset of sexual maturity, age when asymptotic length was achieved, age at death, maximum longevity) and also to estimate undocum…
Effect of simulated faunal impoverishment and mixture on the ecological structure of modern mammal faunas: Implications for the reconstruction of Mio…
2011
15 pages; International audience; The strong link between environment and the ecological diversity of communities is often used for drawing palaeoenvironmental inferences from fossil assemblages. Here we focus on the reliability of fossil samples in comparison to original communities when inferring palaeoenvironments from the ecological diversity of fossil mammal faunas. Taphonomic processes and sampling techniques generally introduce two kinds of biases in fossil samples: 1) the directional impoverishment of communities, i.e. the absence of some specific categories of bones, individuals or species; and 2) the mixture of several communities, temporally (timeaveraging) and/or spatially (spac…
Late Quaternary changes in bat palaeobiodiversity and palaeobiogeography under climatic and anthropogenic pressure: new insights from Marie-Galante, …
2016
25 pages; International audience; Data on Lesser Antillean Late Quaternary fossil bat assemblages remains limited, leading to their general exclusion from studies focusing on Caribbean bat palaeobiodiversity and palaeobiogeography. Additionally, the role of climatic versus human pressure driving changes in faunal communities remains poorly understood. Here we describe a fossil bat assemblage from Blanchard Cave on Marie-Galante in the Lesser Antilles, which produced numerous bat remains from a well-dated, stratified context. Our study reveals the occurrence of at least 12 bat species during the Late Pleistocene and Early Holocene on Marie-Galante, whereas only eight species are currently kn…
Comparing pollen spectra from modified Tauber traps and moss samples: examples from a selection of woodlands across Europe
2010
This paper compares pollen spectra derived from modified Tauber traps and moss samples from a selection of woodland types from Bulgaria, the Czech Republic, Georgia, Greece, Poland, Switzerland and Wales. The study examines the representation of individual taxa in the two sampling media and aims to ascertain the duration of pollen deposition captured by a moss. The latter aim was pursued through the calculation of dissimilarity indexes to assess how many years of pollen deposited in a pollen trap yield percentage values that are most similar to those obtained from the moss. The results are broadly scattered; the majority of moss samples being most similar to several years of pollen depositi…
Biomechanical insights into the dentition of megatooth sharks (Lamniformes: Otodontidae)
2021
AbstractThe evolution of gigantism in extinct otodontid sharks was paralleled by a series of drastic modifications in their dentition including widening of the crowns, loss of lateral cusplets, and acquisition of serrated cutting edges. These traits have generally been interpreted as key functional features that enabled the transition from piscivory to more energetic diets based on marine mammals, ultimately leading to the evolution of titanic body sizes in the most recent forms (including the emblematic Otodus megalodon). To investigate this hypothesis, we evaluate the biomechanics of the anterior, lateral, and posterior teeth of five otodontid species under different loading conditions by…