Investigadores del MNCN aportan nuevos datos sobre los neandertales

Scientific interest in Neanderthals is on the increase. Yolanda Fernandez-Jalvo has provided two perspectives on the species from the sites in Gibraltar and Azokh, in the Caucuses. In Gorham, Gibraltar, inhabited afterwards by H. sapiens, this CSIC researcher has compared the behaviour of the two species in terms of their environmental exploitation. She concludes that competition between them was not totally “devastating”. The behaviour pattern in Azokh was more opportunistic.Peer reviewe

Wood-Concrete and Wood-Wood Mixed Beams: Rational Basis for Selecting Connections

Many studies have approached the problem of mixed beams with a slip at the connection. An analysis of the problem has been carried out globally and Eurocode-5 solves the problem for the use of simple supported beams or similar structures in a precise way and with a simple formulation. Other methods to solve the structural analysis of this issue include matrix as well as several finite-element procedures. Nevertheless, the design process for selecting the connection is now iterative and the variables of the problem can be presented in a more condensed and useful way. The problems of strength and stiffness in this research have been separated. Variables in a powerful nondimensional way and their exact relationships in simple supported beams are presented here. These variables show the nature of the problem in a clear way, and provide a rational basis for selecting the connection

A re-evaluation of the taphonomic methodology for the study of small mammal fossil assemblages of South America

The taphonomic methodology for the study of small mammal fossil was based mainly on actualistic studies of bones and teeth of insectivores (Soricidae, Talpidae, Erinaceidae) and rodents (Arvicolinae, Muridae) recovered from pellets of birds of prey and scats of carnivorous mammals from different places of North America, Europe and Africa. The digestive corrosion patterns on teeth of the South American rodents Sigmodontinae, Caviinae, Ctenomyidae and Abrocomidae, and the marsupials Monodelphini of central Argentina were observed. The comparison between the South American samples with the North American, African and European samples allowed us to establish similarities and differences in the digestive corrosion of the teeth. The main agreements have been recorded in the following groups: Arvicolinae with Caviinae and Abrocomidae; Murinae with Sigmodontinae; Soricidae, Talpidae and Erinaceidae with Monodelphini. However, the particular and simplified configuration of the molars of Ctenomyidae with thicker enamel and dentine exposed has promoted a new description of the categories of digestive corrosion. Likewise Muridae and Sigmodontinae molars, Ctenomyidae presents a delay in the appearance of signs of digestion with regard to other caviomorphs (Caviinae, Abrocomidae). This contribution may, therefore, be useful to know the origin of these South American faunas and the exact taphonomic agent that produced these assemblages. Finally, small mammal samples from an archaeopalaeontological site from Northwestern Patagonia, Argentina, were studied in order to apply the new methodology emerged from the recent samples.Facultad de Ciencias Naturales y Muse

Compressive marks from gravel substrate on vertebrate remains: A preliminary experimental study

Lakeshore sites such as Cerro de la Garita (Miocene of Teruel, Spain) and Senèze (Pliocene of Haute-Loire, France) yielded fossils with distinct puncture marks. These marks were described as >punctures surrounded by plastically deformed bone>, and were proposed to have been caused by compression or trampling on bones against coarse sediment grain when deposited in damp environments. A series of experiments was performed to test this hypothesis. Cow, red deer and fallow deer metapodials were compressed by applying a mechanical load on them against a gravel substrate under dry/damp environments. Results confirm that these characteristic puncture marks are associated with compression efforts on bones in wet environments.Project CGL 2010-19825 was funded by the Spanish Ministry of ResearchPeer Reviewe

The flexibility matrix o timber composite beams with a discrete connection system

This work presents a method for the analysis of timber composite beams which considers the slip in the connection system, based on assembling the flexibility matrix of the whole structure. This method is based on one proposed by Tommola and Jutila (2001). This paper extends the method to the case of a gap between two pieces with an arbitrary location at the first connector, which notably broadens its practical application. The addition of the gap makes it possible to model a cracked zone in concrete topping, as well as the case in which forming produces the gap. The consideration of induced stresses due to changes in temperature and moisture content is also described, while the concept of equivalent eccentricity is generalized. This method has important advantages in connection with the current European Standard EN 1995-1-1: 2004, as it is able to deal with any type of load, variable section, discrete and non-regular connection systems, a gap between the two pieces, and variations in temperature and moisture content. Although it could be applied to any structural system, it is specially suited for the case of simple supported and continuous beams. Working examples are presented at the end, showing that the arrangement of the connection notably modifies shear force distribution. A first interpretation of the results is made on the basis of the strut and tie theory. The examples prove that the use of EC-5 is unsafe when, as a rule of thumb, the strut or compression field between the support and the first connector is at an angle with the axis of the beam of less than 60º

Morphological taphonomic transformations of fossil bones in continental environments, and repercussions of their chemical composition

The aim of this paper is to provide a summary of structural or surface modifications of vertebrate bone remains in continental palaeoenvironments that may have repercussions on their chemical composition. Both before and after burial, a different set of physical, chemical and biological agencies may produce modifications of the bone morphological structure and/or bone chemical composition. Several of these morphological modifications are diagnostic of particular agents, which otherwise may not be noticed or identified in a fossil association. In order to understand diagenesis, those events that occurred before final burial have to be considered, as they may strongly modify the bone morphological structure and influence post-burial changes

Gregariousness in the giant sloth Lestodon (Xenarthra): multi-proxy approach of a bonebed from the Last Maximum Glacial of Argentine Pampas

Megamammals constituted an important component in the Pleistocene faunal communities of South America. Paleobiological and paleoecological studies involving different megamammal taxa have increased significantly in the last years, but there are still several poorly-known issues of its life history. In this work, we analyze an assemblage composed of 13 individuals of different ontogenetic stages, and possibly different sex, belonging to the giant ground sloth Lestodon armatus (Xenarthra, Folivora), recovered from Playa del Barco site (Pampean Region, Argentina). A dating of 19,849 years Cal BP allows assigning this assemblage to a period of the MIS (Marine Isotope Stage) 2 related to the end of the Last Glacial Maximum. Based on multiple lines of research (e.g. taphonomy, paleopathology, osteohistology, isotopy), we interpret the origin of the assemblage and diverse paleobiological and paleoecological aspects (e.g. social behavior, ontogenetic changes, sexual dimorphism, diseases, resource and habitat use, trophic relationships) of L. armatus. Evidence suggests that the assemblage was formed by a local single event of catastrophic mortality, which affected different members of a social group. This record represents the first accurate evidence of gregariousness for this ground sloth, providing new data on a poorly-known behavior among extinct Folivora

Are owl pellets good estimators of prey abundance?

Some ecologists have been skeptics about the use of owl pellets to estimate small mammal's fauna. This is due to the assumptions required by this method: (a) that owls hunt at random, and (b) that pellets represent a random sample from the environment. We performed statistical analysis to test these assumptions and to assess the effectiveness of Barn owl pellets as a useful estimator of field abundances of its preys. We used samples collected in the arid Extra-Andean Patagonia along an altitudinal environmental gradient from lower Monte ecoregion to upper Patagonian steppe ecoregion, with a mid-elevation ecotone. To test if owls hunt at random, we estimated expected pellet frequency by creating a distribution of random pellets, which we compared with data using a simulated chi-square. To test if pellets represent a random sample from the environment, differences between ecoregions were evaluated by PERMANOVAs with Bray–Curtis dissimilarities. We did not find evidence that owls foraged non-randomly. Therefore, we can assume that the proportions of the small mammal's species in the diet are representative of the proportions of the species in their communities. Only Monte is different from other ecoregions. The ecotone samples are grouped with those of Patagonian steppes. There are no real differences between localities in the small mammal's abundances in each of these ecoregions and/or Barn owl pellets cannot detect patterns at a smaller spatial scale. Therefore, we have no evidence to invalidate the use of owl pellets at an ecoregional scale.Fil: Andrade, Analia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico; ArgentinaFil: Menezes, Jorge Fernando Saraiva de. Universidade Federal do Rio de Janeiro; BrasilFil: Monjeau, Jorge Adrian. Universidade Federal do Rio de Janeiro; Brasil. Fundación Bariloche; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Characterization of endosperm proteins and bread-making quality in wheat breeding lines carrying resistance genes for Mayetiola destructor and/or Heterodera avenae.

The experimental material included thirteen bread wheat-breeding lines that carry genes for resistance to M. destruc¬tor and/or H. avenae. The sources of these resistances are the wild species Ae. triuncialis and Ae. ventricosa (lines TR and H-93, respectively) (Delibes et al. 1993, 1997; Romero et al. 1998). We have determined the composition in HMW-glutenin subunits (related with bread-making quality), puroindoline proteins (related with hardness of grain), and waxy proteins (related with starch viscosity). In addition to, of prolamins by electrophoresis SDS-PAGE indicated the homogeneity of the lines