Week 5 Flashcards
Natural burial occurs where there is lots of sediment being deposited, like
- the seafloor
- rivers
- flood plains
Burial protects the
dinosaur fossils from scavengers, transportation, or decomposition at the surface (decomposition rates slow after burial because there is less oxygen available).
Single Animal preservation from best to worst quality fossils:
1) Articulated Skeletons: all bones of animal in life position, animal died and was buried shortly after death.
2) Partially Articulated and Associated Skeletons: pretty good, some bones are in life position. Animal was buried shortly after death following minor transportation.
3) Disarticulated Skeletons: can be put back together if all of the bones are there. No bones are in life position, buried long after death following minor transportation.
4) Isolated Bones: single bone found, extensive transportation and animal was buried long after death.
Multiple Animal Preservation
Bonebeds: lots of large bones. Concentration of macrofossils. Bones are disarticulated or associated. Often caused by mass death.
Microvertebrates: Concentrations of small bones, bone fragments, and other fossils caused by the movement of water. Heavy bones settle in low spots in a river.
9 ways to Fossilize
Freezing Mummification/Desiccation Encasement Replacement Permineralization Petrification Recrystallization Carbonization Molds and Casts
Unaltered remains have been fossilized in which ways?
Frozen
Mummification/Desiccation
Encasement
Mummification can accompany _____ and _____.
Mummification can accompany freezing and encasement.
What kind of preservation is a fossil in a glacier an example of?
Freezing
What kind of preservation is a fossil in amber an example of?
Encasement
You can fossilize by changing the chemical make up of remains, these are called
altered remains.
Replacement
Original bone or shell material is dissolved and another material immediately takes its place, like pyrite or silica (quartz).
This method of preservation leaves no original material.
Permineralization
Water flows through pores and deposits minerals. Bones are porous so this is common in bones.
This method of preservation leaves some original material.
Petrification
Permineralization + replacement, common in wood.
This method of preservation leaves some original material.
Recrystallization
Change the crystal structure or make the crystals bigger, common in shells, making new crystals out of old crystals.
This method of preservation changes original material.
Carbonization
Bury the fossil and squeeze all the water and other volatiles out until there is only a film of carbon left on the rock. Black smear on rock in the shape of the original matter indicates carbonization.
This method of preservation changes original material.
