Fossil glycoproteins of the soluble organic matrix are present in an 80-million-year-old mollusk shell from the Late Cretaceous Period. Discrete molecular weight components, as determined by gel electrophoresis, are preserved. The fossil organic matrix was compared with the organic matrix of a living representative species of the same superfamily. A particular repeating amino acid sequence, fou...

Molecular clock methods allow biologists to estimate divergence times, which in turn play an important role in comparative studies of many evolutionary processes. It is well known that molecular age estimates can be biased by heterogeneity in rates of molecular evolution, but less attention has been paid to the issue of potentially erroneous fossil calibrations. In this study we estimate the ti...

It is inferred from the symmetrical and luminous X-ray emission of fossil groups that they are mature, relaxed galaxy systems. Cosmological simulations and observations focusing on their dark halo and inter-galactic medium properties confirm their early formation. Recent photometric observations suggest that, unlike the majority of non-fossil brightest group galaxies (BGGs), the central early-t...

The genomics revolution offers great promise for resolving the phylogeny of living taxa, but does it offer any benefits for reconstructing relationships among extinct (fossil) taxa? Superficially, the answer would seem to be "no," given that molecular data cannot be obtained for most fossil taxa. However, because fossil taxa often interdigitate among living taxa on the Tree of Life, molecular d...

the kashkan formation (paleocene to middle eocene), consists of conglomerate, sandstone, and siltstone in the zagros folded zone, southwest iran. type of the sedimentary facies, architectural elements and trace fossils show that kashkan deposits were formed in a low sinuosity braided stream system, with north to south flow direction. the formation displays coarsening-upward succession reflects ...

A new fossil mushroom is described and illustrated from the Lower Cretaceous Crato Formation of northeast Brazil. Gondwanagaricites magnificus gen. et sp. nov. is remarkable for its exceptional preservation as a mineralized replacement in laminated limestone, as all other fossil mushrooms are known from amber inclusions. Gondwanagaricites represents the oldest fossil mushroom to date and the fi...

Both the fossil record and molecular data support a long evolutionary history for the Araceae. Although the family is diverse in tropical America today, most araceous fossils, however, have been recorded from middle and high latitudes. Here, we report fossil leaves of Araceae from the middle-late Paleocene of northern Colombia, and review fossil araceous pollen grains from the same interval. Tw...

We study changes in fossil fuel and non-fossil energy use and carbon dioxide emissions induced by carbon taxes. We develop a partial energy equilibrium model with capital and labor as production factors, and endogenous technological change through learning by doing and learning through research, distinguishing between private and public innovations. Our model reproduces the learning curves typi...