33 research outputs found

    A Review of the fossil record of turtles of the clade Baenidae

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    The fossil record of the turtle clade Baenidae ranges from the Early Cretaceous (Aptianā€”Albian) to the Eocene. The group is present throughout North America during the Early Cretaceous, but is restricted to the western portions of the continents in the Late Cretaceous and Paleogene. No credible remains of the clade have been reported outside of North America to date. Baenids were warmadapted freshwater aquatic turtles that supported high levels of diversity at times through niche partitioning, particularly by adapting to a broad range of dietary preferences ranging from omnivorous to molluscivorous. Current phylogenies place Baenidae near the split of crown-group Testudines. Within Baenidae three more inclusive, named clades are recognized: Baenodda, Palatobaeninae and Eubaeninae. A taxonomic review of the group concludes that of 49 named taxa, 30 are nomina valida, 12 are nomina invalida and 7 are nomina dubia

    To fly or not to fly: high flight costs in a large sea duck do not imply an expensive lifestyle

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    A perennial question in ornithology is whether flight has evolved mostly to facilitate access to food or as an anti-predator strategy. However, flight is an expensive mode of locomotion and species using flight regularly are associated with an expensive lifestyle. Using heart rate (HR) data loggers implanted in 13 female common eiders (Somateria mollissima), our objective was to test the hypothesis that a high level of flight activity increases their energy budget. We used the long-term recording (seven months) of HR as an index of energy expenditure and the HR flight signature to compile all flight events. Our results indicate that the eider is one of the thriftiest volant birds with only 10 minutes of flight time per day. Consequently, we were not able to detect any effect of flight activity on their energy budget despite very high flight costs (123ā€“149 W), suggesting that flight was controlled by energy budget limitations. However, the low flight activity of that species may also be related to their prey landscape requiring few or no large-scale movements. Nevertheless, we suggest that the (fitness) benefits of keeping flight ability in this species exceed the costs by allowing a higher survival in relation to predation and environmental harshness

    Proposta de classificaĆ§Ć£o hierarquizada dos modelos de soluĆ§Ć£o para o problema de job shop scheduling A proposition of hierarchical classification for solution models in the job shop scheduling problem

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    Este artigo propƵe uma classificaĆ§Ć£o hierarquizada dos modelos utilizados na soluĆ§Ć£o do problema de programaĆ§Ć£o da produĆ§Ć£o intermitente do tipo job shop, incluindo tanto os que fornecem soluĆ§Ć£o Ć³tima, quanto os modelos heurĆ­sticos mais recentes baseados em mĆ©todos de busca estendida. Por meio dessa classificaĆ§Ć£o obteve-se um painel amplo dos modelos existentes, evidenciando as diferentes abordagens do problema e suas soluƧƵes, com o objetivo de proporcionar uma orientaĆ§Ć£o preliminar na escolha do modelo de job shop scheduling mais adequado.<br>This paper proposes a hierarchical model classification used in the job shop scheduling problem, including those that provide an optimal solution and the more recent ones based on heuristics, called extended search methods. A panel with the existing models is obtained by this classification, and solutions and approach differences are highlighted with the aim of a preliminary orientation on the choice of a more adequate job shop scheduling model
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