Download Learning from the Fossil Record Grade 8 Science Name: Katherine

Learning from the Fossil Record
Grade 8 Science
Name: Katherine Burns
Date: 3/18/11
Part1 of Performance Assessment Task
In analyzing other features around the fossils in each layer, the scientists were able to identify
some key features that struck them as interesting. They have sent you a description of the
environment that existed at each level, based on the features they found in each layer.
Deepest fossil layer: all
short skull and jaw
Long, skinny tail
Long front legs
Long back legs
No flukes on the tail
Next fossil layer:
some
short skull and jaw
Long, skinny tail
Long front legs
Long back legs
No flukes on the tail
Next fossil layer:
all
Long skull and jaw
Short, fat tail
Front flippers
Short back legs
Flukes on the tail
Next fossil layer:
all
Long skull and jaw
Short, fat tail
Front flippers
No back legs
Flukes on tail
Environmental Evidence:
mostly medium trees
some smaller shrubs
many small creeks
some
Environmental Evidence:
long skull and jaw
taller grasses
short, fat tail
small shrubs
short front legs
swampy
long back legs
no flukes on the tail
Environmental Evidence:
taller grasses
shallow ponds
swampy
Environmental Evidence:
larger, deep lakes
many aquatic plants
By studying present day animals with similar traits, they have inferred that:
1. Long skull and jaw are dominant over short skull and jaw
2. Short thick tail are dominant over long skinny tail
3. Long front legs is dominant over short front legs
4. Long back legs is dominant over short back legs
5. No flukes on tail is dominant over flukes on tail
They do know all of these fossils are related as the area was isolated and no other animals
could come in or go out of the area.
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Learning from the Fossil Record
Grade 8 Science
Name: Katherine Burns
Date: 3/18/11
They ask that you add notes to your original report of your findings on the possible genetics and
inheritance of these traits.
Please include, in a new color, the following in your report.
1. Explanations for why the organisms’ features changed from one layer to the next.
Include specifics for each trait that changed.
2. More detailed explanations for those changes that occurred for reasons other than
inheritance.
Each answer will be scored on the following aspects:
a. Does the reasoning behind the answer make sense and is it possible? 0 1 2 3
b. Is the report organized in a logical manner so the reader can understand the explanations
provided? 0 1 2 3
The organisms feature, short skull and jaw, changed from one layer to the next. This
organism changed, by instead of just all short skull and jaws there were some long skull
and jaw organisms. The short skull and jaw is recessive which means it must be tt. This
makes the next layer with short skull and jaw makes sense, but the long skull and jaw
doesn’t. The environment was mostly medium trees, some small shrubs, and many small
creeks. The organism must have had a mutation. I have a feeling that the mutation was
caused by excessive sunlight. To me this is because there were not that many things in
their environment that could protect them from the harmful rays of the sun. The
difference between the 1st layer and the 2nd layer is that the first layer had medium
trees to hide under, but the second layer had taller grasses that they could hide under
a lot more. The difference is the taller grass gives better coverage. This mutation made
their offspring have long skull and jaw; but the people who had not gotten the
mutation still had the normal offspring. The next layer had an environment that had
taller grasses, small shrubs, and it was swampy. This allowed the organisms to hide
through the taller grass and the swamp helped to hide the animals as well. For the next
layer they all had long skull and jaw, which to me means that the short skull and jaw
organisms died. The mutation was an advantage because the short skull and jawed
organisms couldn’t reach the food at the bottom of the deep swamp and all the other
food sources ran out. So they ended up going extinct. The next layer like I said which
had all long skull and jawed organisms had an environment that had taller grasses,
shallow ponds, and swampy. They all had survived to the next layer because they
could reach the food at the top of the tall grass and could still reach the food at the
bottom of the swamp. And the last layer had an environment that had larger, deep
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Learning from the Fossil Record
Grade 8 Science
Name: Katherine Burns
Date: 3/18/11
lakes and many aquatic plants. The long skull and jaw could survive and the mutation
stayed as an advantage.
The organisms feature, Long front legs, changed from one layer to the next. This
organism changed, by instead of just all long front legs there were some short front
legged organisms in the next layer. The long front legs is dominant which means it could
be either Ll or LL . This makes the next layer with some of both type of organisms make
sense because when they cross some could be either. The environment was mostly
medium trees, some small shrubs, and many small creeks. The organism must have had
a mutation. I have a feeling that the mutation was caused by excessive sunlight. To me
this is because there were not that many things in their environment that could protect
them from the harmful rays of the sun. The difference between the 1st layer and the 2nd
layer is that the first layer had medium trees to hide under, but the second layer had
taller grasses that they could hide under a lot more. The difference is the taller grass
gives better coverage. This mutation made their offspring have short front legs; but the
people who had not gotten the mutation still had the normal offspring. The next layer
had an environment that had taller grasses, small shrubs, and it was swampy. Even
thought they could still hide in the tall grass the organisms cell must have misread the
DNA because they now had front flippers. For the next layer they all had front flippers,
which to me means that the short and long front legs had been not been getting
enough food to survive and that the mutation from the cells misreading the DNA was
an advantage. This is because they could swim faster to get enough food without tiring
themselves out and not having to walk on the bottom of the swamp so they could get
further into the swamp where it was deep. The mutation was an advantage because
the front flippered organisms couldn’t swim far enough into the swamp and had to try
to get enough food in the shallow part while probably half the population was doing
the same thing. So they ended up going extinct. The next layer like I said which had all
front flippered organisms had an environment that had taller grasses, shallow ponds,
and swampy. They all had survived to the next layer because they could reach the
food because they all had the advantage. And the last layer had an environment that
had larger, deep lakes and many aquatic plants. The front flippered could survive and
the mutation stayed as an advantage.
The organisms feature, Long back legs, changed from one layer to the next. This
organism changed, by instead of just all long back legs there were all long back
legged organisms still in the next layer. The long back legs is dominant which means it
could be either TT. This makes the next layer with all of the same type of organisms
make sense because when they cross they would be all be long back legs. It could be
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Learning from the Fossil Record
Grade 8 Science
Name: Katherine Burns
Date: 3/18/11
either but homozygous dominant makes it more realistic; if it was heterozygous when
they cross there would be a small percent that could be homozygous recessive. The
environment was mostly medium trees, some small shrubs, and many small creeks. The
environment helped to keep all the organisms alive protecting it. For the next layer they
all had short back legs, which to me means that there was a mutation. This mutation
must have been from radiation. The United Sates was working on perfecting a nuclear
bomb. When they shot it and it landed in the mountains by the area where the
organisms are; and the wind took the radiation over and they all got mutations. Now
their cells read the gene that says short back legs. This is because of the mutation. The
mutation was an advantage for the organisms because the environment had taller
grass, and swampy area, and small ponds, which means that they were able to just go
where ever they want. This meant that the long back legged organisms were extinct.
They all had survived to the last layer but now every organism had no back legs. I have
a feeling that this is because something went wrong within the cell and the cell ended
up misreading the new mutation. But because the cell misread the new DNA the
organism can now swim in the environment. The misread mutation became an
advantage! And the last layer had an environment that had larger, deep lakes and
many aquatic plants. The no back legged organisms could survive in the new
environment and the misread mutation stayed as an advantage.
The organisms feature, long skinny tails, changed from one layer to the next. This
organism changed, by instead of long skinny tails that all of them had in the beginning,
some were short fat tails in the next layer and some were the same as long skinny tails.
The long skinny tail is recessive ss. But it was still the more popular one over the dominant
short fat tailed genes. This makes the next layer make sense. Because in the next fssil
layer, short fat tails became equally popular with long skinny tails. The environment was
mostly medium sized trees, some small shrubs, and many small creeks. The organism
must have had a mutation. I have a feeling that the mutation was caused by excessive
sunlight or chemicals in the creeks. I believe that this is because that the chemicals in
the creek must have either killed or mutated the animal. And somehow recreated or
made the short tail dominant gene reappear. This mutation must have spread to
offspring over a few generations until it was equally popular to the long skinny tail gene.
The next layer had an environment that had taller grasses, small shrubs, and swampy.
This allowed other organisms to hide in the tall grass, and the swampy environment
would be good for being safe from predators. For the next layer they all had short fat
tails. Which to me seems like all of the other organisms with long skinny tails died. The
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Learning from the Fossil Record
Grade 8 Science
Name: Katherine Burns
Date: 3/18/11
mutation was obviously an advantage because maybe the long tails would get stuck in
the swampy ground. While the short tails wouldn’t, or the dominant short tail trait spread
so is was just the completely dominant gene. So they ended up going extinct. The next
layer had taller grasses small ponds and was swampy. Where all of the organism
species had short fat tails. And nothing had really changed. And finally in the last layer
there were large lakes and many aquatic plants. And the species remained the same
with the short fat tail being the only existing trait for the species…at least for now.
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