Tooth replication techniques, SEM imaging and microwear analysis in Primates: methodological obstacles

Dental microwear analyses are among the most significant techniques though which a researcher can make dietary and ecological inferences from primate fossil specimens. Hard particles, such as plant phytoliths or silica-base sands, can scratch tooth enamel surfaces during food mastication producing a dietary specific pattern of microwear on the enamel surface. The density, axis length and orientation of microwear features, either striations or pits, are highly informative of dietary habits in both extant and fossil primates. The analysis of tooth enamel surfaces requires the use of scanning electron microscopy (SEM) techniques, because of its high resolution power, including gold-coating of teeth for observation. Problems arise when specimens to be analysed are unique and there is no possibility of a direct observation with an environmental microscope. Negative moulds must then be made and silicone-base components are indicated for high quality replication of enamel surfaces. A positive cast needs to be obtained, and epoxy-base resins are frequently used for their good quality and durability. However, successive silicon and epoxy replications result in the loosing of surface detail and precision. Surface observation errors can also be caused be the SEM technology itself, especially if back-scattered electrons are used instead of secondary electrons for maximizing the topographical information of enamel images. This paper reviews the most commonly used methodological approaches to tooth moulding and casting, comparing SEM micrographs of casts with actual tooth surfaces, and contrasting the reliability of SEM images for dietary interpretation of tooth microwear in both extant and fossil primates

Buccal enamel microwear variability in Cercopithecoidea Primates as a reflection of dietary habits in forested and open savanna environments

Dental microwear analysis has proved to be a good indicator of diet and dietary related behaviour in modern humans, fossil hominids and primates. The composition of the diet and the presence of dust and other abrasive particles, are related to microwear rates on the buccal enamel surfaces of molar teeth. Plant food materials such as leaves or stems include phitoliths in larger quantities than fruits or meat. These particles may scratch the enamel surface of teeth during mastication producing a microwear pattern that may be indicative of food choice and food preferences within primate species. In this study we present a dental microwear analysis of extant Cercopithecoidea primates, based on the analysis of more than 200 dental casts obtained from the osteological collection of the National Museum of Kenya (NMK). Specific, sub-specific and also ecological differences are shown to underlie the buccal microwear variability observed within the studied sample

Wetland restoration and nitrate reduction: the example of the periurban wetland of Vitoria-Gasteiz (Basque Country, North Spain)

Changes in land use and agricultural intensification caused wetlands on the quaternary aquifer of Vitoria-Gasteiz (Basque Country) to disappear some years ago and nitrate concentration in groundwaters increased very quickly. The Basque Government recently declared the East Sector of this aquifer a Vulnerable Zone according to the 91/676/CEE European Directive. Recently, the wetlands have been restored through the closure of the main drainage ditches, the consequent elevation of the water table and the abondonment of agricultural practices near the wetlands. This is the case of the Zurbano wetland. Restoration has allowed the recovery of its biogeochemical function, which has reduced nitrate concentrations in waters. Nitrate concentrations which exceed 50 mg l–1 in groundwaters entering into the wetland are less than 10 mg l–1 at the outlet. Conditions in the wetland are conducive to the loss of nitrates: organic matter rich wetted soils, clay presence allowing a local semiconfined flow and very low hydraulic gradient. Water quality monitoring at several points around the wetland showed the processes involved in nitrate loss, although some aspects still remain unresolved. However, during storm events, the wetland effectively reduces the nitrate concentration entering the Alegria River, the most important river on the quaternary aquifer

Organic vs Conventional Suckling Lamb Production: Product Quality and Consumer Acceptance

Samples of suckling lambs (n=40) of two breeds reared under conventional and organic conditions were analysed to asses physico-chemical characteristics, including instrumental texture, and nutritional quality in terms of fatty acid composition. Consumer acceptance was also studied using the home-use test. Results revealed that organic suckling lamb meat is healthier as shown by the lower saturated fatty acid levels, the higher polyunsaturated fatty acid contents and the higher 6/3 ratiko. The organic meat had lower instrumental hardness, received higher scores in all sensory parameters, and had statistically better fat sensation and higher ratings for overall liking. These results lend support to the notion among consumers that organic products are healthier and tastier

Consumer Appreciation of Carcass Quality of Organic vs Conventional Suckling Lamb Production

Carcass characteristics of sucking lambs (n= 40) of two breeds reared under conventional and organic conditions were analysed including objective and subjective parameters for fatness and conformation, meat and fat colour. Consumer acceptance was also studied using the home-use test. Results showed that the characteristics of the carcass of suckling lamb were similar for both types of production systems pointing out that organic production system did not affect fatness or muscle development. However, organic meat was darker (higher L* and a* values) probably related with the higher amount of exercise, although fat was not more yellow. In contrast consumers did not consider organic meat darker and there were not significant differences in appearance related with the similar conformation. These results reflect that consumer perceive organic meat as at least as good as conventional production not only regarding environmental quality but also regarding carcass quality

Testing dietary hypotheses of East African hominines using buccal dental microwear data

Abstract There is much debate on the dietary adaptations of the robust hominin lineages during the Pliocene-Pleistocene transition. It has been argued that the shift from C3 to C4 ecosystems in Africa was the main factor responsible for the robust dental and facial anatomical adaptations of Paranthropus taxa, which might be indicative of the consumption of fibrous, abrasive plant foods in open environments. However, occlusal dental microwear data fail to provide evidence of such dietary adaptations and are not consistent with isotopic evidence that supports greater C4 food intake for the robust clades than for the gracile australopithecines. We provide evidence from buccal dental microwear data that supports softer dietary habits than expected for P. aethiopicus and P. boisei based both on masticatory apomorphies and isotopic analyses. On one hand, striation densities on the buccal enamel surfaces of paranthropines teeth are low, resembling those of H. habilis and clearly differing from those observed on H. ergaster, which display higher scratch densities indicative of the consumption of a wide assortment of highly abrasive foodstuffs. Buccal dental microwear patterns are consistent with those previously described for occlusal enamel surfaces, suggesting that Paranthropus consumed much softer diets than previously presumed and thus calling into question a strict interpretation of isotopic evidence. On the other hand, the significantly high buccal scratch densities observed in the H. ergaster specimens are not consistent with a highly specialized, mostly carnivorous diet; instead, they support the consumption of a wide range of highly abrasive food items

New Lower Devonian Polygnathids (Conodonta) from the Spanish Central Pyrenees, with comments on the early radiation of the group

The comprehensive study of six Pragian-lower Emsian (Lower Devonian) sections from the Spanish Central Pyrenees has yielded a rich assemblage of conodont faunas, highlighting an important succession of Polygnathus species. Among them, the presence of the biostrati­graphical markers P. pireneae, P. kitabicus, P. excavatus excavatus and P. exc. 114 stands out. This conodont succession allows the identification of the Pragian/Emsian boundary and the early Emsian zones and subzones: the kitabicus Zone and the Lower and Middle excavatus subzones. It is also remarkable the presence of three new polygnathid species: P. aragonensis n. sp., P. carlsi n. sp. and P. ramoni n. sp. Additionally, P. pannonicus and P. sokolovi are also reported for first time in the Iberian Peninsula. According to all these records, the abundance and diversity of these species suggest that during this time interval an evolutionary radiation of the group took place, identifying two pulses during the early radiation of the group. The first one during the pireneae-kitabicus Zone, and a second one during the Lower excavatus Zone. The new data presented herein increase considerably the known paleobiodiversity of the genus dur­ing the Pragian-early Emsian interval in the Spanish Central Pyrenees and corroborates the presences of the most important early Emsian conodont markers used in other regions such us Europe, North Africa, Central Asia, Australia, and North America. ozonas Dc, E y F asociados al evento de enfriamiento global del Mioceno medio.El estudio en profundidad de seis secciones de edad Emsiense (Devónico Inferior) del Pirineo Central español ha proporcionado una rica asociación de conodontos, destacando una importante sucesión de especies del género Polygnathus. Entre ellos, resalta la presencia de los marcadores bioestratigráficos P. pireneae, P. kitabicus, P. excavatus excavatus y P. exc. 114. Esta sucesión de conodontos per­mite la identificación del límite Praguiense/Emsiense, así como de las principales zonas del Emsiense temprano: la Zona kitabicus y las subzonas excavatus Inferior y Media. También es destacable la presencia de tres nuevas especies de polygnátidos: P. aragonensis n. sp., P. carlsi n. sp. y P. ramoni n. sp.; junto con la primera referencia en la Península Ibérica de las especies P. pannonicus y P. sokolovi. De acuerdo con estos resultados, la abundancia y diversidad de estas especies sugiere que durante este intervalo temporal se produjo una radiación evolutiva del grupo, identificando dos momentos de la misma durante la evolución temprana del grupo. El primero durante el intervalo pireneae-kitabicus, y el segundo durante la Zona excavatus Inferior. Los nuevos datos presentados en este trabajo incrementan considerablemente la paleobiodiversidad conocida del género durante el Praguiense final y comienzos del Emsiense en el Pirineo Cen­tral español, y corrobora la presencia de los principales marcadores biostratigráficos del Emsiense inferior registrados en otras regiones como Europa, norte de África, Asia Central, Australia y América del Norte

Nota metodológica: Alteración del patrón de microestriación dentaria por el efecto wrinkle.

Se describe el efecto wrinkle observado por primera vez sobre moldes dentarios realizados con resinas epoxy y metalizados en oro para su observación mediante microscopía electrónica de barrido (SEM). Con el fin de determinar en qué medida puede afectar al análisis del patrón de microestriación vestibular, se analizan dos muestras dentales de tres especies de Hominoideos, una de ellas incluyendo moldes con presencia de"aguas" relacionadas con el proceso de metalización. Se observa un descenso marcado de la variabilidad del patrón de microestriación dentaria anque las diferencias entre las dos muestras por especie no son estadísticamente significativas. El efecto wrinkle reduce significativamente el porcentaje de clasificación correcta de las especies analizadas a partir del patrón de microestriación y rugosidad dental utilizando un Análisis Discriminante. Se aconseja evitar la inclusión de las muestras afectadas por aguas en los estudios del patrón de microestriación dentaria

Self-organization of ultrasound in viscous fluids

We report the theoretical and experimental demonstration of pattern formation in acoustics. The system is an acoustic resonator containing a viscous fluid. When the system is driven by an external periodic force, the ultrasonic field inside the cavity experiences different pattern-forming instabilities leading to the emergence of periodic structures. The system is also shown to possess bistable regimes, in which localized states of the ultrasonic field develop. The thermal nonlinearity in the viscous fluid, together with the far-from-equilibrium conditions, are is the responsible of the observed effects