نتایج جستجو برای: plant fossils
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Fossils are vital for calibrating rates of molecular and morphological change through geological time, and are the only direct source of data documenting macroevolutionary transitions. Many evolutionary studies therefore require the robust phylogenetic placement of extinct organisms. Here, we demonstrate that the inevitable bias of the fossil record to preserve just hard, skeletal morphology sy...
Algae and plants are the dominant primary producers on our planet and define an evolutionarily diverse group of taxa (Graham and Wilcox 2000). Despite their importance, dating algal origin is frustrated by a limited fossil record (Knoll 1992). Recent molecular phylogenetic trees place algae near the base of the eukaryotic tree of life (e.g., Baldauf et al. 2000, 2003; Nozaki et al. 2003). This ...
The sudden appearance of fossils that marks the so-called 'Cambrian explosion' has intrigued and exercised biologists since Darwin's time. In On the Origin of Species, Darwin made it clear that he believed that ancestral forms 'lived long before' their first fossil representatives. While he considered such an invisible record necessary to explain the level of complexity already seen in the foss...
We studied the presence of immunoglobulin G (IgG) in equid fossil bones from Venta Micena (Granada, Spain), dated at 1·6 Myr old, and from Atapuerca (Burgos, Spain) (0·12 Myr), and in ostensibly hominid fossils VM1960 and VM3691 (1·6 Myr) from Venta Micena and CV1 and CV2 (1·4 Myr) from Cueva Victoria (Murcia, Spain). Samples taken from the specimens were crushed to a fine powder and their mine...
Phytolith remains of rice (Oryza sativa L.) recovered from the Shangshan site in the Lower Yangtze of China have previously been recognized as the earliest examples of rice cultivation. However, because of the poor preservation of macroplant fossils, many radiocarbon dates were derived from undifferentiated organic materials in pottery sherds. These materials remain a source of debate because o...
Molecular and morphological data have important roles in illuminating evolutionary history. DNA data often yield well resolved phylogenies for living taxa, but are generally unattainable for fossils. A distinct advantage of morphology is that some types of morphological data may be collected for extinct and extant taxa. Fossils provide a unique window on evolutionary history and may preserve co...
Figs (Ficus; ca 750 species) and fig wasps (Agaoninae) are obligate mutualists: all figs are pollinated by agaonines that feed exclusively on figs. This extraordinary symbiosis is the most extreme example of specialization in a plant-pollinator interaction and has fuelled much speculation about co-divergence. The hypothesis that pollinator specialization led to the parallel diversification of f...
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