Dating of dinosaur fossils intelligent dating headlines
If this happens rapidly before significant decay to the organic tissue, very fine three-dimensional morphological detail can be preserved.
Nodules from the Carboniferous Mazon Creek fossil beds of Illinois, USA, are among the best documented examples of such mineralization.
Replacement occurs when the shell, bone or other tissue is replaced with another mineral.
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.
For this reason, one term covers the two modes of preservation: adpression.
Because of their antiquity, an unexpected exception to the alteration of an organism's tissues by chemical reduction of the complex organic molecules during fossilization has been the discovery of soft tissue in dinosaur fossils, including blood vessels, and the isolation of proteins and evidence for DNA fragments.
In many cases, however, compressions and impressions occur together.
Compression fossils, such as those of fossil ferns, are the result of chemical reduction of the complex organic molecules composing the organism's tissues.
is any preserved remains, impression, or trace of any once-living thing from a past geological age.