Methods of Preservation

Question 1

external molds

Answer 1

imprints of organism, embedded in rocks

Question 2

casts

Answer 2

external molds are filled with sediment

Question 3

internal molds

Answer 3

sediment fills dead organism & remains after decomposed to show internal features.

Such organisms include bivalves and gastropods.

Question 4

Petrification/Petrifaction/Silicification

Answer 4

minerals slowly replace organic tissues of organism.

Most common mineral-silicon, but others work too.

Question 5

Carbonization/Coalification

Answer 5

over time all parts of the original organism except the carbon removed from fossil.

Remaining carbon is the same stuff organism was made of.

Question 6

trace fossil

Answer 6

not part of organism.

Examples: footprints, burrows, eggshells, coprolite (💩)

These give insights into the organism’s behavior.

Question 7

Actual Remains

Answer 7

Still intact parts of organism.

Ex: Mammoth hair - frozen and still preserved.

Much rarer than other fossil types.

Question 8

Mummification

Answer 8

Preserves organism with some tissue/skin intact. Very fragile.

(Mummification is NOT true fossilization.)

Happens in cold/dry places where preservation is quick/effective.

Question 9

Tar/Tar-pit fossils

Answer 9

organism trapped in tar bc of oxygen-deprived environment.

(Ex- La Brea tar pit in Los Angeles)

Due to the oxygen-deprived enviromnent, it allows for rapid burial and well-preserved parts.

Question 10

Amber

Answer 10

Hardened tree resin. Organism is trapped in biologically inert environment. Preserved wholly.

(exoskeletons are kinda altered, but soft inner tissues are gone.)

Insects are usually trapped in amber

Question 11

Freezing

Answer 11

Requires special circumstances to preserve soft (organic) parts. Encompasses orgaism in inert environment to prevent changes.

Freezing is one of the ways to solw down decomposition of soft parts.