Lesson 2 Flashcards

1
Q

What is meant by the term taphonomy

A
  • it is the study of all natural processes that occur after the death of an organism
  • > this includes how it decays, is scavenged by other organisms and becomes fossilized

-note plastic deformation is a type of taphonomy

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2
Q

What is the bloat-and-float phenomenon

A
  • it is when a carcass’ body swells with putrid gasses

- >this causes the carcasses of large animals to float easily and be transported by water

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3
Q

How can taphonomic factors contribute to the disarticulation of a skeleton

A

1)Partial consumption by carnivores

2) Carcasses being swept away by water
- >water may carry the skeletons to different locations as well

3)Prolonged exposure to sunlight

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4
Q

What is plastic deformation in relation to the weight of layers of rock and sediment above a fossil

A
  • plastic deformation occurs when the pressure causes the shape of a buried fossil to change
  • > even when the pressure is removed
  • > the fossil does not return to its original shape
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5
Q

What needs to happen to a bone for it to be fossilized

A

-it needs to be buried

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6
Q

What are the different ways burial can happen

A
  • an animal dies in its own burrow
  • it falls into a sinkhole
  • one of its bones is buried by a predator
  • or most often burial happens when water washes sand or mud over a carcass
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7
Q

Is fossilization more common in wet or dry environments

A
  • it is more common among wet environments

- >because in dry environments, there is no water to bury the fossil

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8
Q

Is fossilization more common at low or high elevations

A
  • it is more common at low elevations
  • > where sand and mud carried in by water are able to build up

-at high elevations, sand and mud are often carried away by erosion before they can build up permanently bury and protect a carcass

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9
Q

What are river and stream deposits

A

-they are referred to as fluvial deposits

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10
Q

What are animals that died and preserved in lakes referred to as

A
  • they are referred to as lacustrine deposits
  • > they have a better chance of preserving soft tissues like hair or feathers in fossils
  • > this is because there is very little water movement in the lake to disrupt the skeleton
  • > therefore, the sediments laid down in the lakes are very fine grained
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11
Q

Are there dinosaurs usually found in sediments representing ancient deserts

A
  • no there is not

- >because there wasn’t enough sediment being deposited to preserve the skeleton

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12
Q

Describe why Mongolia is unique in the formation of sediments

A
  • because it is an ancient desert
  • there was a river that coursed through this desert
  • > the river formed a huge oasis
  • > therefore, the dinosaurs had a chance to be buried by the sediments that were deposited by the river

-dinosaurs in Mongolia could also be buried by sand dunes that suddenly collapsed onto a living animal

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13
Q

What are sedimentary rocks

A

-rocks that form when mineral and organic particles accumulate and become either cemented or compacted together

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14
Q

What are igneous rocks

A

-they form when magma or lava cools

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15
Q

What are metamorphic rocks

A

-they form when sedimentary or igneous rocks are changed by heat and pressure

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16
Q

What is sedimentology

A

-it is the science of how sedimentary rocks form

17
Q

What are mudstones and shales

A
  • they are sedimentary rocks that form from mud and silt

- >lakes are places where large amounts of mud and silt accumulate

18
Q

What are sandstones

A
  • they are sedimentary rocks that form from sand

- >sandstone can indicate a former beach, river channel, or ocean floor environment

19
Q

What is coal

A
  • it is a sedimentary rock
  • > that forms from the compressed remains of plants
  • > it indicates a former swampy environment
20
Q

What is limestones

A
  • they are formed from the accumulation of shells and exoskeletons of small marine invertebrates
  • > it is an indication of a former shallow marine environment
21
Q

What is the term describing the different ways that fossils form

A
  • it is referred to as preservation styles

- >most dinosaur bone fossils form through either permineralization or replacement

22
Q

What is permineralization

A
  • it occurs when the empty internal spaces of a bone are filled with minerals
  • > these minerals are first dissolved in water and then deposited in the empty bone spaces as water soaks through the bone
23
Q

What is replacement

A

-it occurs when the original bone gradually decays and minerals fill the space that the bone once occupied

24
Q

How is a fossil prevented from eroding away

A
  • it must remain buried
  • > however, the burial process must be partially reversed in order for the fossil to be near enough to the surface to be found
  • > therefore, dinosaur fossils are found in modern environments where there is recent erosion
25
Q

Is vegetation a good place to find fossils?

A
  • no
  • > vegetation covers and holds together an environment’s topsoil and prevents erosion
  • eg; badlands are really good places to hunt for fossils today
  • > their erosion rates are high
  • > vegetation is sparse
26
Q

What is the first step in the excavation of a fossil

A
  • overburden removal
  • > overburden is the rock and earth that covers a fossil specimen and that must be removed
  • > before the full extent of the specimen can be judged
  • involves tools like shovels, pickaxes and occasionally jackhammers and bulldozers
  • > note jackhammers and bulldozers are not used in close proximity to the fossil
27
Q

Does a bone need to be mapped before it is dug up?

A
  • yes
  • > mapping the relative positions of the bones may help putting a skeleton back together
  • > also gives important taphonomic clues
28
Q

What are the ways to protect a bone during its transportation

A
  • wrap it in a protective material
  • > cloth, paper towel, or aluminum foil
  • > then covered by strips of burlap that have been soaked in plaster