Lecture 14+15 (Fossils)

Question 1

How old are fossils?

Answer 1

Over 11 000 years

Question 2

How old are subfossils?

Answer 2

Less than 11 000 years

Question 3

What is the most important condition for something to become a fossil?

Answer 3

It must be buried quickly

Question 4

Which areas have the highest rate of fossilization?

Answer 4

Areas with a high rate of accumulation (prevents organic matter decay)

Question 5

What is analytical connection?

Answer 5

The body of the organism is completely in tact

Question 6

What are oxic conditions?

Answer 6

Conditions of the environment have oxygen dissolved into them. Benthic organisms exist and destroy dead organisms

Question 7

What are anoxic conditions?

Answer 7

No oxygen. Benthic organisms do not exist to destroy a dead organism, therefor better chance to fossilize!

Question 8

What are usually the first things to vanish during fossilization?

Answer 8

Pigments

Question 9

What are the 3 different kinds of fossils?

Answer 9

1) Body Fossils
2) Trace Fossils (ichnofossils)
3) Chemical Fossils (Biomarkers)

Question 10

What are body fossils?

Answer 10

Direct, or altered remains of ancient organisms (teeth, shells etc)

Question 11

What are trace fossils?

Answer 11

Evidence of the activity of ancient organisms

Question 12

What are chemical fossils?

Answer 12

Organic compounds produced by various organisms that exist in the strata

Question 13

What are the 6 types of fossil preservation?

Answer 13

1) Recrystallization
2) Moldic Preservation
3) Perminerallization
4) Carbonization
5) Congealment
6) Fossilization in Amber

Question 14

What is recrystallization?

Answer 14

Conversion of the original minerals into different minerals.

Question 15

What is the most common transformation during the process of recrystallization?

Answer 15

Aragonite (grey, translucent)—> Calcite (white, opaque)

Question 16

What is moldic preservation?

Answer 16

When the original test or shell is dissolved. Shape of the former organism is given by lithified sediment infill.

Question 17

What is the mold and what is the cast in moldic preservation?

Answer 17

Mold: Preserves exterior
Cast: Preserves interior

Question 18

What is moldic preservation replacement?

Answer 18

The empty space created by moldic preservation has fluids which continue to circulate and precipitate mineral. Can get a well preserved fossil with weird physical properties (Mass of minerals without order)

Question 19

What is the most frequent case of replacement?

Answer 19

Pyritization-gold!!

Question 20

What is permineralization?

Answer 20

Occurs in certain organisms with hard, porous body parts (ex: vertebrate bone). Soft tissue decays, then fluid fills the bone pores with inorganic material like opal or chalcedony

Question 21

What is carbonization?

Answer 21

Kind of fossilization wherein the fossil is buried deep within the Earth’s crust and all the organic material is expelled, except carbon.

Question 22

What is the most frequent organism fossilization?

Answer 22

Carbonization

Question 23

What are 2 of the more rare forms of fossilization and what makes them unique?

Answer 23

Congealment and Fossilization in Amber- able to preserve the bodies 3D structure

Question 24

What is congealment?

Answer 24

Occurs at high latitudes where low temp is kept constant over long periods. Soil at the surface is frozen and forms permafrost. Frozen swamps form. Organisms are trapped and killed by swamp.

Question 25

What is fossilization in amber?

Answer 25

Secreted by conifers that developed 100 million years ago. Amber is sticky, and highly viscose. Animal gets trapped and engulfed.

Question 26

Can you extract DNA from amber fossils?

Answer 26

No, the DNA decays

Question 27

What are Tar Pits?

Answer 27

Hydrocarbons reaching the surface of water, creating a toxic tar pit. Animals in proximity die instantly. If they fall in, perfect preservation.