Lesson 2 Flashcards
What is meant by the term taphonomy
- 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
What is the bloat-and-float phenomenon
- 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
How can taphonomic factors contribute to the disarticulation of a skeleton
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
What is plastic deformation in relation to the weight of layers of rock and sediment above a fossil
- 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
What needs to happen to a bone for it to be fossilized
-it needs to be buried
What are the different ways burial can happen
- 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
Is fossilization more common in wet or dry environments
- it is more common among wet environments
- >because in dry environments, there is no water to bury the fossil
Is fossilization more common at low or high elevations
- 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
What are river and stream deposits
-they are referred to as fluvial deposits
What are animals that died and preserved in lakes referred to as
- 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
Are there dinosaurs usually found in sediments representing ancient deserts
- no there is not
- >because there wasn’t enough sediment being deposited to preserve the skeleton
Describe why Mongolia is unique in the formation of sediments
- 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
What are sedimentary rocks
-rocks that form when mineral and organic particles accumulate and become either cemented or compacted together
What are igneous rocks
-they form when magma or lava cools
What are metamorphic rocks
-they form when sedimentary or igneous rocks are changed by heat and pressure
What is sedimentology
-it is the science of how sedimentary rocks form
What are mudstones and shales
- they are sedimentary rocks that form from mud and silt
- >lakes are places where large amounts of mud and silt accumulate
What are sandstones
- they are sedimentary rocks that form from sand
- >sandstone can indicate a former beach, river channel, or ocean floor environment
What is coal
- it is a sedimentary rock
- > that forms from the compressed remains of plants
- > it indicates a former swampy environment
What is limestones
- they are formed from the accumulation of shells and exoskeletons of small marine invertebrates
- > it is an indication of a former shallow marine environment
What is the term describing the different ways that fossils form
- it is referred to as preservation styles
- >most dinosaur bone fossils form through either permineralization or replacement
What is permineralization
- 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
What is replacement
-it occurs when the original bone gradually decays and minerals fill the space that the bone once occupied
How is a fossil prevented from eroding away
- 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
