CHAPTER 2 Flashcards
Taphonomy
The study of all natural processes that involve an organism after it dies.
explain BLOAT-AND-FLOAT
shirty after death, the body will swell up with putrid gases, this can cause the carcass to float easily and to be transported by shallow and weakly water.
plastic deformation
occurs when pressure causes the shape of the fossil to be changed so that when the pressure is later removed, the fossil does not return to its original shape.
where is fossilization most common, and why?
In wet environments, cuz a fossil needs to be buried, most common burial is when water washes sand or mud over a body.
Fluvial deposits
sediments transported and deposited in river or streams.
animals that died and were preserves in lakes are called _____
Lacustrine deposite
sedimentary rock
rocks that form when mineral and organic particles accumulate and become either cemented or compacted together.
igneous rock
rocks which form from magma or cooled lava.
metamorphic rock
when sedimentary or igneous rocks are changed by heat or pressure.
mudstone and shale
sedimentary rocks that form from mud and silt
sandstone
sedimentary rocks that from from sand
coal
sedimentary rock that from from compressed remains of plants.
what can coal indicate
a former swampy environment
preservation styles
the many different ways a fossil forms.
permineralization
occurs when empty internal spaces of a one are filled with minerals. these minerals first dissolve in water and then are deposited into the empty spaces of the bone.
replacement
occurs when the original bone gradually decays and minerals fill the space that the bone once occupied.
badlands
modern environments that are covered with considerable erosion, and where vegetation is sparse, ad large expanses of sedimentary rock is exposed.
what is the first step in excavation of a large fossil
removing the overburden
overbruden
the rock and earth that covers a fossil and must be removed. removed using indelicate tools like shovels.
bonebeds
accumulations of bones of many dinosaurs
disarticulation
when parts of the skeleton are separated.
what may cause disarticulation
occur as. carnivores eat the carcass, or because it was transported by water.
orientation
long bones that are aligned in the same direction indicate that the bones were transported by water.
abrasion
(process of waring and scraping) gives a relative sense for how far the bones may have been transported by flowing water or tooth marks (means carnivore’s fed on carcass)
where is fossilization more common in terms of elevations and why?
low elevations where water can bring in mud and sand and allow it to build up
why is fossilization worse in high elevations?
because sand and mud are often carried away from erosion bemire they can build up and cover/protect a body.
why is it easier to preserve soft tissue and hair like feathers in water.
- Because very little water movement to disrupt the skeleton
- sediments laid down in the lakes are very fine grained, making it easier to preserve feather impressions.
why don’t we find dinosaurs in sediments representing ancient deserts?
And if there is how does that happen?
because there isn’t enough sediment being deposited to preserve the skeleton.
If there is a Dino found most likely due to Aeolian or wind based deposits
Sedimentology
The science of how sedimentary rocks form.
what can be a clue to learning about the habitat of the fossil organism?
understanding environmental conditions that led to the formation of sedimentary rocks
what are reasons why a fossil may be destroyed or not found by a palaeontologist?
they could have melted or metamorphosed by geological processes deep within the earth or have eroded away to dust on earth surface.
or they could have been buried too deep.
what are geologic maps used for ?
To identify locations where there are exposures of sedimentary rocks that are the right age to contain fossils.
what is the ideal dinosaur skeleton or fossil?
one that has been freshly or only just nearly exposed above ground.
Why is it important to map the relative locations and positions of fossils?
mapping the relative positions of bones may help in putting the skeleton back together, and give taphonomic clues.
what does long limb bones that share an orientation mean?
means that the bones were carried by a strong river and that this river oriented the limb bones in line with its current.
How are individual map sheets used?
individual map sheets are combined and digitized to form a map of the entire Dino bone bed.
what do Individual map sheets allow for us to understand ?
allows us to understand the distribution of different bones within the quarry:
- whether or not small bones are found together or mixed in with larger bones
- If the long bones are aligned in the same direction
- if the bones are articulated together still.
what does the palaeontologist do once the overburden is removed ?
they map out the fossil, and then it’s ready to be dug up.
steps to procedure after the fossil has been dug up.
1) protect the bone by wrapping it in layers of protective material.
2) covered by strips of burlap that have been soaked in plaster. which forms a jacket, not opened until arrived to the lab.
3) once at the lab, special glues are applied to the fossil to strengthen it.
4) the final work on removing the surrounding rock takes place in the lab.
where does removing the last of the surrounding rock around the fossil.
In the lab.
name all of the types of sedimentary rocks.
- mudstone and shale
- limestone
- sandstone
- coal
which rock are almost all fossils found in
sedimentary rocks, few fossils have exceptions.
what do large deposits of mudstone and shale indicate ?
can indicate former lake bottom environment.
what do large deposits of sand stone indicate?
indicate former beach river channel, or coastal environment.
what do large deposits of coal indicate?
inside a former swampy environment.
what are the two preservation styles most fossils from through?
permineralization and replacement.
what tools are used to remove overburden ?
large indelicate tools like picks, hammers, shovels.
