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539 Ma – present. The Phanerozoic Eon (Greek: period of well-displayed life) marks the appearance in the fossil record of abundant, shell-forming and/or trace-making organisms. It is subdivided into three eras, the Paleozoic, Mesozoic and Cenozoic, with major mass extinctions at division points.
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Bioconcentration. In aquatic toxicology, bioconcentration is the accumulation of a water-borne chemical substance in an organism exposed to the water. [ 1][ 2] There are several ways in which to measure and assess bioaccumulation and bioconcentration. These include: octanol-water partition coefficients (K OW ), bioconcentration factors (BCF ...
Geological history of oxygen. Before photosynthesis evolved, Earth's atmosphere had no free diatomic oxygen (O 2 ). [ 2] Small quantities of oxygen were released by geological [ 3] and biological processes, but did not build up in the atmosphere due to reactions with reducing minerals. Oxygen began building up in the atmosphere at approximately ...
Global biodiversity is the measure of biodiversity on planet Earth and is defined as the total variability of life forms. More than 99 percent of all species [ 1] that ever lived on Earth are estimated to be extinct. [ 2][ 3] Estimates on the number of Earth's current species range from 2 million to 1 trillion, but most estimates are around 11 ...
The geologic time scale is a way of representing deep time based on events that have occurred throughout Earth's history, a time span of about 4.54 ± 0.05 Ga (4.54 billion years). [ 5] It chronologically organises strata, and subsequently time, by observing fundamental changes in stratigraphy that correspond to major geological or ...
The timeline displays a graphical representation of the adaptations; the text attempts to explain the nature and robustness of the evidence. Plant evolution is an aspect of the study of biological evolution, predominantly involving evolution of plants suited to live on land, greening of various land masses by the filling of their niches with ...
Entropy and life. Research concerning the relationship between the thermodynamic quantity entropy and both the origin and evolution of life began around the turn of the 20th century. In 1910 American historian Henry Adams printed and distributed to university libraries and history professors the small volume A Letter to American Teachers of ...