Week 4 Flashcards
Microbial decay
Fungi and bacteria break down dead organic matter further at the cellular and molecular level
Physical (mechanical) and Chemical Weathering of fossils
Physical weathering mechanically breaks down hard, mineralized tissues (e.g. shells, bone, teeth).
Mineralized tissues also tend to dissolve (via chemical weathering), and erode, if exposed at the surface.
Factors that tend to promote the preservation of remains
1) Absence of oxygen (slows down decomposition process, discourages scavenging)
2) Rapid burial (discourages scavenging, prevents scattering of pieces)
3) Precipitation of stable minerals in/on remains after burial
Hardpart Preservation
more likely to be preserved close to their original state because they are less prone to breakdown
Recrystallization
Most hardparts experience some degree of recrystallization after burial.
Crystals tend to increase in size due to the higher temperatures encountered below Earth’s surface.
Petrifaction
Occurs when mineral matter fills small pores of the remains of an organism
Replacement
When organic matter or minerals of an organism are replaced by different mineral substances. Occurs at a microscopic level
Carbonization
Carbon-rich remains such as plant matter is lightly heated when buried.
During this low-grade cooking, elements such as oxygen are released, while carbon is left behind.
As a result, the remains are enriched in carbon.
Formation of jet
Jet is an extremely hard, gem variety of coal formed from fossil wood of Araucaria trees that later experienced near metamorphic conditions of heat and pressure.
Moulds
3D impression of a fossil
Casts
Formed when an external mould is infilled by sediment or precipitated minerals. It appears as a replica of the original buried object.
Body Fossil
represent body tissue
Trace Fossil
record the activities of ancient organisms
The difference between body and trace fossils
While body fossils tell us things about the anatomy of organisms, trace fossils provide evidence of behaviour
Fractal
a geometrical shape or pattern made up of identical parts, repeating the pattern
EX. snowflake
Common shapes in nature
1) Planispiral
2) Helix
3) Hexagon
4) Fractals
Planispiral
Shapes like shrimp and snail shells
Helix
A lop-sided/stretched out sprial
EX. tornadoes, ram horns, DNA
Hexagon
Maximizes structural integrity
EX. honeycomb
