Radiocarbon dating is used to measure the age of fossils
Small scale permineralization can produce very detailed fossils.
For permineralization to occur, the organism must become covered by sediment soon after death or soon after the initial decay process.
In some cases mineral replacement of the original shell occurs so gradually and at such fine scales that microstructural features are preserved despite the total loss of original material.
A shell is said to be recrystallized when the original skeletal compounds are still present but in a different crystal form, as from aragonite to calcite.
The three-domain system of biological classification as proposed by Carl Woese and others (in 1977) classifies organisms into the following domains: archaea (archaeabacteria), bacteria (eubacteria), and eucarya (eukaryotes). Organisms may also be grouped based on their cellular composition.
A single-celled organism is one that consists of only one cell.
This chemical change is an expression of diagenesis.
to dinosaurs and trees, many meters long and weighing many tons.A fossil normally preserves only a portion of the deceased organism, usually that portion that was partially mineralized during life, such as the bones and teeth of vertebrates, or the chitinous or calcareous exoskeletons of invertebrates.Fossils may also consist of the marks left behind by the organism while it was alive, such as animal tracks or feces (coprolites).Compression fossils, such as those of fossil ferns, are the result of chemical reduction of the complex organic molecules composing the organism's tissues.In this case the fossil consists of original material, albeit in a geochemically altered state.