Fossil Preservation (Chapter 3) Flashcards
1
Q
Taphonomy
A
- “death study”
- study of biological & geological processes that occur between death of organism & its final state in rock
- biological processes: predation, scavenging
- geological processes: weathering, diagensis
2
Q
body fossils
A
actual body of organism; e.g. trilobite’s skeleton
3
Q
trace fossil
A
records of activities done by organisms; e.g. trilobite’s trail
4
Q
hard part
A
- shell, bone, or woody tissues
- e.g. shell of Lingula rectilate
- good chance of preservation
5
Q
soft part
A
- organic tissues
- e.g. body of Lingula rectilate
- poor chance of preservation
6
Q
calcium carbonate preservation
A
argonite material recrystallizes to calcite since former is unstable; can also be preservation of origninal material
7
Q
silica preservation
A
- permineralization (pore filled) of woody tissues by silica
- orginal preservation of organisms (e.g. diatoms)
8
Q
phosphate preservation
A
- of soft parts - early mineralization at low rate of burial & high organic content
- usually replacement of elements in chemcial composition
- allow preservation of original morphological details
9
Q
iron oxides preservation
A
- of soft parts - rapid burial & low organic content & presence of sulfates in sediments
- coating of pyrite around soft parts may leads to replacement of hard parts composed of calcium carbonate by pyrite
10
Q
siderite preservation
A
- siderite mineral (combination of iron & carbonate) replaces original material & preserve shape or outline of organism
- e.g. fossilized claw of Protocallianassa mortowi
11
Q
carbonization preservation
A
- parts (esp. soft parts) are heated & compressed, only carbon film remains
- process likely to occur in anoxic, organic-rich environment; e.g. swamps
- sediments → shales
12
Q
clay preservation
A
- clay filled up spaces of organism & take shape even when original material disappeared
- especially good for shelly organism, e.g. ammonite
13
Q
amber preservation
A
- way of preserving fossils by envelop material in fossilized resin (amber)
- usually well-preserved since amber is resilient & can preserve both hard & soft parts
14
Q
original shell/ unaltered preservation
A
- original material/shell is intact without chemical alteration in mineralogy
- usually due to burial after sof parts decayed
15
Q
mold
A
original body has decayed but left an impression on surrounding sediments
16
Q
cast
A
orginal body has decayed and its space is replaced later with another material, a perfect replica
17
Q
internal vs. external cast
A
- internal - minerals filled in species of a hollow organic structure/cavity which decayed later
- external - minerals filled in mold and recreate outer surface of organism that left the mold.
