The girdle epidermis of adult Mopalia muscosa secretes several types of structures, including calcareous spicules and innervated hairs. Newly metamorphosed chitons superficially resemble adult animals, but they lack the adult girdle ornaments, shell sculpture, and coloration. The morphogenesis of the adult girdle structures has not been described previously for any species. Juvenile Mopalia mus...

[1] A high-resolution record of exceptionally well preserved calcareous nannofossil assemblages from Tanzania is marked by two key transitions closely related to the climatic events of the Eocene-Oligocene transition (EOT). The first transition, at 34.0 Ma, precedes the first positive shift in dO and coincides with a distinct interval of very low nannofossil abundance and a cooling in sea surfa...

Biostratigraphic data provided by the sections of the Caravaca–Cehegı́n region, SE Spain, have contributed decisively to the lively debate that has taken place in recent years concerning the Berriasian/Valanginian boundary. This work presents the results from new integrated stratigraphic analyses of these sections, based on the distribution of ammonites, calpionellids and calcareous nannofossils...

Accumulation of heavy metals from agricultural soils contaminated by low levels heavy metals has important implications in the understanding of heavy metal contamination in the food chain. Through field experiments (1994-1996), the influence of thermal regime under different treatments on the accumulation of zinc, cadmium, copper, and lead in Chinese cabbage [Brassica pekinensis (Lour) Rupr. cv...

Calcareous dinophytes produce exoskeletal calcified structures during their life history (a unique character among the alveolates) and are subsumed under the Thoracosphaeraceae as part of the Peridiniales. We provide a brief synopsis about the taxonomic history of the group, from the first descriptions of fossils in the 19th century through to the results of molecular phylogenetics studies unde...

A procedure to determine the exchanger-phase composition (and thus the Na/Ca selectivity) of calcareous and gypsiferous soils was developed and tested on three soils and three phyllosilicate minerals. The procedure corrects for anion exclusion and mineral weathering by measuring the Cl, SO,,, and HCO3 in the soil solution and in the extracting solution. Anion exclusion was found to be significa...

Three new species of calcareous sponges from the coast of Bahia State, NE Brazil are described. All of them belong to the genus Paraleucilla (Calcaronea, Leucosolenida, Amphoriscidae): P. solangeae sp. nov., P. oca sp. nov., and P. incomposita sp. nov. The number of species recorded from the Bahia coast has thus increased from 10 to 13. Including these new species, there are now 50 calcareous s...

We present a field application of a new in situ technique to analyze phase transformations of fine lead oxide particles (50-100mum) in different soils directly in the field over 18 months. After the first month of exposure to a calcareous sand we found newly precipitated secondary mineral phases on the lead oxide. The samples exposed to two loamy soils (Dystric Cambisol and Luvisol) showed only...

Calcareous microplankton shells form the dominant components of ancient and modern pelagic sea-floor carbonates and are widely used in palaeoenvironmental reconstructions. The efficacy of these applications, however, is dependent upon minimal geochemical alteration during diagenesis, but these modifying processes are poorly understood. Here we report on new biomineralization architectures of pr...