of fossilization
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The Fossilization Flow Chart FOSSIL! Trace Fossils Body Fossils Unaltered Remains Encasement •Amber •Tar Mummification Freezing Altered Remains Some Original Material Original Material Changed No Original Material Permineralization Replacement Carbonization Molds and Casts Pyritization Silicification Tracks Borings Burrows Coprolite Recrystallization FOSSIL! Trace Fossils Body Fossils Unaltered Remains Encasement •Amber •Tar Mummification Freezing Altered Remains Some Original Material Original Material Changed No Original Material Tracks Borings Burrows Coprolite MOST OF THESE ARE NOT MUTUALLY EXCLUSIVE IN A GIVENCarbonization SPECIMEN!! Permineralization Recrystallization Replacement Molds and Casts Pyritization Silicification FOSSIL! Trace Fossils Body Fossils Unaltered Remains Encasement •Amber •Tar Mummification Freezing Altered Remains Some Original Material Original Material Changed No Original Material Permineralization Replacement Carbonization Molds and Casts Pyritization Silicification Tracks Borings Burrows Coprolite Recrystallization Trace Fossils (AKA “Ichnofossils”) EVIDENCE OF AN ORGANISMS ACTIVITIES (tracks, borings, burrows, coprolites) Tracks (locomotion) Burrows (domocile) Borings (domocile or feeding) Coprolite (digestion) FOSSIL! Trace Fossils Body Fossils Unaltered Remains Encasement •Amber •Tar Mummification Freezing Altered Remains Some Original Material Original Material Changed No Original Material Permineralization Replacement Carbonization Molds and Casts Pyritization Silicification Tracks Borings Burrows Coprolite Recrystallization Body Fossils The actual remains of ancient organisms (as opposed to traces of life) Bones Teeth Wood/plants Shells Exoskeleton Any part of a body from an animal older than 10,000 years old! FOSSIL! Trace Fossils Body Fossils Unaltered Remains Encasement •Amber •Tar Mummification Freezing Altered Remains Some Original Material Original Material Changed No Original Material Permineralization Replacement Carbonization Molds and Casts Pyritization Silicification Tracks Borings Burrows Coprolite Recrystallization Altered Remains Body fossils that have been changed in some way after the organism died. Many fossils are formed this way. Molds and casts Permineralization Pyritization Carbonization Recrystallization FOSSIL! Trace Fossils Body Fossils Unaltered Remains Encasement •Amber •Tar Mummification Freezing Altered Remains Some Original Material Original Material Changed No Original Material Permineralization Replacement Carbonization Molds and Casts Pyritization Silicification Tracks Borings Burrows Coprolite Recrystallization Permineralization A common form of fossilization where the pore spaces of a skeletal element (bones, teeth, shells, etc.) are filled in by minerals that have precipitated from groundwater. Some original material from the original element remains. Many fossil bones and teeth have been at least partially permineralized Pore spaces filled in with a mineral (usually quartz or calcite) Petrified wood is another good example, though replacement and recrystallization can also be factors in fossil wood FOSSIL! Trace Fossils Body Fossils Unaltered Remains Encasement •Amber •Tar Mummification Freezing Altered Remains Some Original Material Original Material Changed No Original Material Permineralization Replacement Carbonization Molds and Casts Pyritization Silicification Tracks Borings Burrows Coprolite Recrystallization Replacement The slow, microscopic process of exchanging molecules from the original bone or skeletal element with molecules that were not associated with the organism before death. This means that no original material is left in the fossil unlike in permineralization. A type of replacement called pyritization where all of the original material is replaced by “fool’s gold” or pyrite This type of replacement, silicification, has replaced the original calcium carbonate shell with a mineral called quartz FOSSIL! Trace Fossils Body Fossils Unaltered Remains Encasement •Amber •Tar Mummification Freezing Altered Remains Some Original Material Original Material Changed No Original Material Permineralization Replacement Carbonization Molds and Casts Pyritization Silicification Tracks Borings Burrows Coprolite Recrystallization Molds and Casts In this type of fossilization, the original fossil creates an impression on the surrounding rock creating a mold. A cast would be created if the space where the original shell was then filled in with new sediment. If sediment was to fill in the external mold on the left, then a cast would be formed. So it would look similar to the half of the actual shell, but be made of sediment. External Mold------ Shell------ Internal Mold FOSSIL! Trace Fossils Body Fossils Unaltered Remains Encasement •Amber •Tar Mummification Freezing Altered Remains Some Original Material Original Material Changed No Original Material Permineralization Replacement Carbonization Molds and Casts Pyritization Silicification Tracks Borings Burrows Coprolite Recrystallization Carbonization This mode of preservation occurs when heat and pressure chemically transform “volatile compounds” (such as nitrogen, hydrogen, and oxygen found in protein) and leave a carbon film. Carbonized bee Carbonized eurypterid FOSSIL! Trace Fossils Body Fossils Unaltered Remains Encasement •Amber •Tar Mummification Freezing Altered Remains Some Original Material Original Material Changed No Original Material Permineralization Replacement Carbonization Molds and Casts Pyritization Silicification Tracks Borings Burrows Coprolite Recrystallization Recrystallization In this process, unstable minerals from the original organism are transformed to more stable minerals. This most commonly occurs in animals with shells made of minerals called aragonite or highmagnesium calcite (like sea urchins!) that is highly unstable and transforms into more stable calcite. The original shell material from this gastropod has been changed to a more stable form of calcium carbonate This one is visibly harder to observe but the coral has transformed from aragonite to more stable calcite FOSSIL! Trace Fossils Body Fossils Unaltered Remains Encasement •Amber •Tar Mummification Freezing Altered Remains Some Original Material Original Material Changed No Original Material Permineralization Replacement Carbonization Molds and Casts Pyritization Silicification Tracks Borings Burrows Coprolite Recrystallization Unaltered Remains Body fossils in which the original material hasn’t been changed or replaced by another substance Encasement in amber Encasement in tar Freezing Usually only very young coral and shells are found unaltered
