Carlton C. Allen, Frances Westall, Teresa Longazo, Rachel Schelble, Luke Probst, and Beverly Flood NASA Johnson Space Center, Houston, TX 77058 [email protected] Centre de Biophysique Moleculaire, Orleans France, Hernandez Engineering, Houston, TX 77058, University of Southern California, Los Angeles, CA 90089, Rice University, Houston, TX 77005, Texas A & M University at Galveston, Galv...

asmari formation was deposited in the foreland zagros basin (southwest iran). in this research, biostratigraphy related to the asmari formation in north of khorram abad, robat namaki section, is discussed. in the studied stratigraphic section, the asmari formation overlies the shahbazan formation and underlies gachsaran formation and consists of cream to gray medium to thick limestone and marl....

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...

Organically preserved algal microfossils from the Ringwood evaporite deposit in the Gillen Member of the Bitter Springs Formation (late Precambrian of central Australia) are of small size, low diversity, and probable prokaryotic affinities. These rather primitive characteristics appear to reflect the stressful conditions that prevailed in a periodically stagnant, hypersaline lagoon. This assemb...

Contents 1. Introduction 2. Biological and morphological species concepts 3. Evidence from ecology and palaeobiology 3.1. The cichlid fishes of the African rift valleys 3.2. Sticklebacks and speciation by natural selection 3.3. Ice ages and species migrations 3.4. The punctuated equilibrium revolution 3.5. Stasis 3.6. Speciation and ecophenotypic change: the rift valley snails 4. Fossil evidenc...

The oldest sediment most recently recovered from the Arctic Ocean is a biosiliceous ooze nearly devoid of nonbiogenic particles and exhibiting small-scale color changes. Color variations are due to changes in iron and manganese content. These elements are probably of local hydrothermal origin, and the Mn precipitation may be bacteria-mediated. An iron silicate phase seems to form at the expense...

Microproblematica are microfossils whose suprageneric taxonomic status is unknown. Many microproblematica display an encrusting way of life and can therefore be included in the group of “micro-encrusters” that during the Upper Jurassic were conspicuous components of microbial carbonate crusts (e.g. LEINFELDER et al., 1993; SCHMID, 1996; DUPRAZ & STRASSER, 1999, 2002). These forms are widespread...