#5 - Of the dinosaurs of the birdlike group called ornithomimids,

[Jeff Wren]

Complete Question Explanation

Strengthen. The correct answer choice is (D).

The stimulus presents an argument involving causal reasoning.

The argument begins by describing a birdlike group of dinosaurs called ornithomimids and the fact that the later ornithomimids had toothless beaks and weak jaw muscles. A particular species of the later ornithomimids, the Gallimimus bullatus, had a comblike plate inside its beak. Since modern ducks and geese also have similar comblike plates and strain small bits of food from water and mud (combined with the fact that the later ornithomimids had toothless beaks and weak jaw muscles, which would probably rule out some other types of eating), the paleontologists hypothesize that the Gallimimus bullatus also fed by filtering food from water and mud.

Here, the causal reasoning is implied rather than stated outright. The implied cause is the comblike plate in the beak and the effect is straining bits of food from water and mud to eat. To strengthen this argument, we'd like to strengthen the connection between the cause and the effect. There are several main ways to do so, including eliminating possible alternate causes, showing more examples of the cause and effect occurring together, supporting the data itself, etc..

The argument relies on the comparison between modern ducks and geese to the Gallimimus bullatus, so any answer that strengthens the similarity between these species in the relevant way (in other words, their comblike plates and filtering food behavior) would also strengthen the argument.

Answer choice (A): This answer provides an alternate hypothesis about how some dinosaurs with toothless beaks and weak jaw muscles may have eaten. If anything this answer would weaken the argument by providing a possible alternate method that the Gallimimus bullatus might have been able to eat without having to filter food from mud and water.

Answer choice (B): Knowing that toothless beaks and weak jaw muscles were not common to other dinosaur groups has no effect on whether the Gallimimus bullatus filter food from water and mud as we don't know anything about whether these other dinosaurs had comblike plates and what their eating behaviors were.

Answer choice (C): Because the argument is relying on the similarities between the Gallimimus bullatus and modern ducks and geese, this answer actually would weaken the argument as it emphasizes the anatomical differences between them.

Answer choice (D): This is the correct answer choice. The fact that most of the fossils of the Gallimimus bullatus were found in lakes, rivers, and other wet environments suggests that these dinosaurs spent much of (if not all of) their lives in these environments. Given that dinosaurs would likely spend most of (if not all of) their lives near their food source, this strengthens the connection between the causal relationship. While this answer doesn't prove for certain that the paleontologists are correct in their hypotheses, we are not being asked to do so in this question, only to provide some additional support.

Answer choice (E): The fact that paleontologist have not found evidence of any other dinosaurs that had comblike plates has no effect on the causal relationship between the comblike plates and the filtering of food from water and mud. It therefore has no effect on the argument. It's possible that the Gallimimus bullatus was the only known dinosaur to have the comblike plate and also to filter food from mud and water.

[Fightforthat170]

Hi PS

I'm confused as why D is a better answer than C.

D states that most fossils of GB were found in wet places. To me, this answer choice merely indicates the locations of this species' death, or not even that, the fossils or bones could be brought to a wet environment by flood or other geographical movements.

However, the hypothesis is about their eating habits, which imho is more linked to C. Even though I admit that C can be poked holes here and there, such as "sharing anatomical features with modern ducks and geese means nothing since they don't need to share anatomical features to eat by filtering food from water and mud," however, compared to the rest of the answer choices, I do think C would be the more digestible answer. It provides a possibility such as that "animals fed by filtering food from water and mud needs a special digestive system."

Please help!

[Adam Tyson]

The problem with answer C, Fightforthat170, is that it adds no new helpful evidence to support the conclusion that G. bullatus ate using some sort of filtration method. In fact, it weakens the argument by showing that despite some similarities, these dinos were not all that similar to ducks and geese, modern birds that do eat that way. Answer C reduces the value of the comparison that was the author's only evidence! To strengthen an argument based on a comparison you want to validate the comparison, not undermine it.

You might be putting too much pressure on answer D, expecting it to prove the conclusion when all it has to do is "bolster the support" (strengthen). While the location of the fossils doesn't prove anything about what they ate, finding them only in wet places certainly goes in the "plus" column for the claim that they ate by filtering water and mud. A good strengthen answer only has to help a little bit, which this answer does by putting most of the creatures that we know about in places where they could do what the paleontologists claimed they did. Imagine how much it would weaken the argument if the opposite were true, and these fossils were only ever found in deserts and other dry environments, and it becomes even clearer how this answer helps, even if only a little.

[Fightforthat170]

The problem with answer C, Fightforthat170, is that it adds no new helpful evidence to support the conclusion that G. bullatus ate using some sort of filtration method. In fact, it weakens the argument by showing that despite some similarities, these dinos were not all that similar to ducks and geese, modern birds that do eat that way. Answer C reduces the value of the comparison that was the author's only evidence! To strengthen an argument based on a comparison you want to validate the comparison, not undermine it.

You might be putting too much pressure on answer D, expecting it to prove the conclusion when all it has to do is "bolster the support" (strengthen). While the location of the fossils doesn't prove anything about what they ate, finding them only in wet places certainly goes in the "plus" column for the claim that they ate by filtering water and mud. A good strengthen answer only has to help a little bit, which this answer does by putting most of the creatures that we know about in places where they could do what the paleontologists claimed they did. Imagine how much it would weaken the argument if the opposite were true, and these fossils were only ever found in deserts and other dry environments, and it becomes even clearer how this answer helps, even if only a little.

Thank you Adam! I just found out that I read C as "Besides the comblike plates... they share a few features..." instead of "EXCEPT FOR the comblike plates... they share a few features..."

EXCEPT FOR means they share a few anatomical features BUT THEY DON'T SHARE THE COMBLIKE PLATE. No wonder you said it actually weakens the comparison!! That is so sneaky I was baffled by this question for two whole days!

[Adam Tyson]

I think you may have that backwards, Fighting, and it's because you have added a word to that answer choice that changes its meaning. It's not that they share A few features; it's that they share FEW features (leave out that "a"). If they share few features, then they have very little in common other than the comblike plate. While having that feature still could suggest they use it as a filter, having little else in common with ducks and geese still weakens the argument by undermining the comparison.

[Fightforthat170]

I think you may have that backwards, Fighting, and it's because you have added a word to that answer choice that changes its meaning. It's not that they share A few features; it's that they share FEW features (leave out that "a"). If they share few features, then they have very little in common other than the comblike plate. While having that feature still could suggest they use it as a filter, having little else in common with ducks and geese still weakens the argument by undermining the comparison.

Oh...! Yes thank you Adam that makes much more sense now. Such a subtle difference.

[sammydz]

Obviously when I read answer choice "D" I eliminated it, because where the fossils are found does not address the eating habits of this type. ( They ate plants and insects, and then slept in the mud) idk.

Therefore I went back to answer choice B and forced the following argument. What are the origins of these modern ducks who strain small bits as their eating habits?
If every other bird type (and the assumption is that modern birds originated from bird-like dinosaurs) had strong jaws and teeth, why are modern ducks sifting their food? it must follow that ducks come from the G. Billutus.
This would bolster the support that the G. Billutus too sifted from mud and water.

Both of these arguments are bad.

How am I supposed to know which argument the LSAC thinks is the better argument?

[nicizle]

I'm not really understanding why E is an incorrect answer choice at all. If the argument is bolstering the idea that the GB dinosaur probably filtered their food through their beaks due to them having the comblike plates in their beaks, then how would saying that the GB dinosaurs were the only dinosaurs with these plates not bolster the argument?

[Luke Haqq]

Hi nicizle!

The conclusion of this stimulus is the final sentence: "Paleontologists therefore hypothesize that G. bullatus fed by filtering food from water and mud." Why does the author conclude this? The author reasons that G. bullatus has a comblike plate in its beak that is similar to what modern ducks and geese possess, animals that get their own food by filtering food from water and mud. Answer choice (D) strengthens this by affirming that G. bullatus lived in the right type of habitat for this to be possible.

Answer choice (E) wouldn't really do anything to this argument. Suppose that there were other dinosaurs that had comblike plates. It's possible that these dinosaurs too would have fed by filtering food from water and mud. Suppose that there weren't any other dinosaurs that has comblike plates. Even if that were the case, it wouldn't really address whether G. bullatus fed by filtering food from water and mud--for example, if all G. bullatus fossils were found in dry environments, then it would be hard to make sense of the conclusion, and that would still be the case whether or not any other dinosaurs also had comblike plates.