Origin and evolution of gnathostome dentitions: A question of teeth and pharyngeal denticles in placoderms

Article Abstract:

A presentation of new data on the phylogenetic origins of teeth and pharyngeal denticles is provided, focusing on the jawed vertebrate group Placodermi, phylogenetically based jawed vertebrates and sister-taxon to the crown-group Gnathostomata. Tooth sets and tooth whorls in crown-group gnathostomes are suggested to drive from the pharyngeal denticle whorls, at least in sharks, with the patterning mechanisms co-opted to the oral cavity.

Australia, Dentition, Endoderm, Placoderms

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Colored nectar: Distribution, ecology, and evolution of an enigmatic floral trait

Article Abstract:

The geographical and taxonomical distribution of colored nectar in flowering plants is examined, and the knowledge about species with colored nectar and the lineages in which they occur is summarized. The possible environmental and ecological correlates of colored nectar are analyzed, also discussing the ecological functions and evolution of this enigmatic flower trait.

United States, Sexual behavior, Physiological aspects, Botany, Angiosperms, Plant taxonomy, Pollination, Properties, Nectar

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The fundamental processes in ecology: a thought experiment in extraterrestrial biospheres

Article Abstract:

Research proposes a process-based approach to ecology, which suggest that a biosphere based on a single species with no food cycling is unlikely to exist. Data show that some processes tend to extend the lifespan of a biosphere or a positive Gain effect, whereas others either increase or decrease represent the negative Gain effect.

Analysis, Evaluation, Influence, Environmental aspects, Biological diversity, Biodiversity, Biotic communities, Ecology, Biosphere, Carbon cycle (Biogeochemistry), Carbon cycle

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