Preservation of Fossil Remains (L11)

Question 1

What is the field of taphonomy?

Answer 1

can be defined most simply as the study of post-mortem processes

Question 2

What processes are included in Taphonomy?

Answer 2

the causes of death itself,
and
processes of decay and disintegration

Question 3

What does it mean that Fossilization tends to be the exception rather than the rule?

Answer 3

it means that for remains of living things to become a fossil, it requires exceptional conditions in order to happen

Question 4

Two ways that detruction of remains in death?

Answer 4

large scavengers take the soft tissues and scatter the hard parts

insects come and lay their eggs on hte dead remain (larvae makes tissue decompose)

Question 5

What do microbes do in the cellular and molecular level?

Answer 5

they break down organic matter further

Question 6

What is dissolution?

Answer 6

The chemical breakdown of hardparts by dissolving of their minerals (a form of chemical weathering)

Question 7

What is Abrasion?

Answer 7

meaning erosion of hard tissues due to “sandblasting” effects of suspended sediment particles

Question 8

What is the general rule of survival of fossil records?

Answer 8

Hardparts have a greater chance of survival in the fossil record than do soft tissues

Question 9

Why is that hardparts have a greater chance of survival?

Answer 9

because they are more robust and stable and are more resistant to destruction overall

Question 10

But why are hardparts rarely preserved fully intact?

Answer 10

because soft tissue decay removes connective tissues, like ligaments, and etc that held the hard parts together

Question 11

Disarticulation?

Answer 11

Dissociation and scattering of hard parts

Question 12

Fragmentation?

Answer 12

meaning the actual breakage of these dissociated elements

Question 13

Why are action of waves and currents on dead remains viewed in a negative way? What are some special cases where its not?

Answer 13

because they usually lead to their transportation from where the animal actually lived, and also tend to be destructive to the remains.

but sometimes, the orientations of fossil remains disturbed after death can indicate aspects of the environment in which they were deposited

Question 14

What are 3 factors that favour the preservation of remains and why?

Answer 14

an absence of oxygen (keeps scavengers away)

and rapid burial (discourages savenging)

Chemical reactions in porewaters of the sediment promote percipitation of more minerals in/on remiains fater burial

Question 15

What are the 2 mienral forms that calcium carbonate occur in?

Answer 15

aragonite - chemically unstable at and near Earth’s surface

calcite - tends to be more chemically stable

Question 16

what is another common skeletal material?

Answer 16

silica - in the form of opal

Question 17

What is the form of calcium phosphate in skeletal materian and in which parts is it found?

Answer 17

Apatite occurs in vertebrate bones and teeth

Question 18

What kind of preservation happens of skeletal remains composed of stable minerals?

Answer 18

it gets preserved without significant change in chemical makeup or internal structure

Question 19

What are 2 examples of stable minerals

Answer 19

Calcite and Silicia

Question 20

Why are hardparts more prone to be preserved close to their original state?

Answer 20

b/c they are lessp prone to breakdown

Question 21

What is aragonite?

Answer 21

the other mineral form of calcium carbonate compoosed of sheets of aragonite crystals and less chemically stable than calcite

Question 22

In what type of rocks are most if not all fossils preserved in?

Answer 22

sediment

Question 23

What is permafrost?

Answer 23

how frozen remains of extinct organisms are found in (extremely rare)

Question 24

How do permafrosts happen?

Answer 24

mammoths or animals could be walking on the surface of a glacier, fall into the water which freezes

Question 25

What is another medium where you can find fossils and what is it specifically?

Answer 25

Amber

is a fossil tree resin, with antibacterial properties that stop remains from bacterial decay

Question 26

What are the 4 main types of alteration processes

Answer 26

Recrystalization
Petrifaction
Replacement
Carbonization

Question 27

Recrystalization

Answer 27

under conditions of higher temp and pressures than at the surface, the crystal of a given mineral tend to increase in size, which leads to the LOSS OF FINE DETAILS IN A FOSSIL

Question 28

Petrifaction (Permineralization)

Answer 28

occurs when mineral matter fills pores of the remains of an organism

occurs in bones b/c they are very porous.

Question 29

What is hte mineral that fills the pores (Petrifaction) of dino bones

Answer 29

Chalcedony (form of silica)

Question 30

Replacement

Answer 30

When organic matter or minerals of an organism can be replaced by diff mineral substances

occurs at microscopic level

Question 31

In “replacement” what are calcite shells commonly replaced with?

Answer 31

silica, pyrite, or apatite

Question 32

Carbonization

Answer 32

when carbon rich remains have their elements released with carbon left behind through low-grade cooking whcih results from light heat of burial

As a result, the remains are enriched in carbon

Question 33

Carbonization

Answer 33

when carbon-rich remains such as plant tissue have their elements released through low-grade cooking that results from light heat of burial

only carbon is left beheind making the remains enriched in carbon

Question 34

What is an example of Carbonization?

Answer 34

Coal

Question 35

External Mould

Answer 35

when a hollow object like clam is buried, with its valves held together, sediment surrounds the object and produces this

Question 36

Internal Mould

Answer 36

is when sediment gets inside the clam and fills the empty space and when the shell dissolves, we are left with an internal mould

Question 37

How are Casts formed?

Answer 37

when an external mould is infilled by sediment or precipiated minerals

appears as a REPLICA of the original buried object

Question 38

How are casts produced?

Answer 38

like chocolate easter bunnies