Editing Taphonomy (section)

===Mixing of fossils from different places===
A [[sedimentology|sedimentary]] deposit may have experienced a mixing of noncontemporaneous remains within single sedimentary units via physical or biological processes; i.e. a deposit could be ripped up and redeposited elsewhere, meaning that a deposit may contain a large number of fossils from another place (an '''allochthonous''' deposit, as opposed to the usual '''autochthonous'''). Thus, a question that is often asked of fossil deposits is to what extent does the fossil deposit record the true biota that originally lived there? Many fossils are obviously autochthonous, such as rooted fossils like [[crinoid]]s,{{clarify|reason=all crinoids are "obviously" autochthonous? Meaning they were never moved by geologic processes? THIS IS NOT OBVIOUS, is it even true at all?|date=August 2018}} and many fossils are intrinsically obviously allochthonous, such as the presence of photoautotrophic plankton in a benthic deposit that must have sunk to be deposited. A fossil deposit may thus become biased towards exotic species (i.e. species not endemic to that area) when the sedimentology is dominated by gravity-driven surges, such as mudslides, or may become biased if there are very few endemic organisms to be preserved. This is a particular problem in [[palynology]].{{citation needed|date=April 2021}}