Because dinosaurs were reptiles, scientists once assumed that, like al

Question

Because dinosaurs were reptiles, scientists once assumed that, like all reptiles alive today, dinosaurs were cold-blooded. The recent discovery of dinosaur fossils in the northern arctic, however, has led a number of researchers to conclude that at least some dinosaurs might have been warm-blooded. These researchers point out that only warm-blooded animals could have withstood the frigid temperatures that are characteristic of arctic winters, whereas cold-blooded animals would have frozen to death in the extreme cold.

Which one of the following, if true, weakens the researchers' argument?

(A) Today's reptiles are generally confined to regions of temperate or even tropical climates.

(B) The fossils show the arctic dinosaurs to have been substantially smaller than other known species of dinosaurs.

(C) The arctic dinosaur fossils were found alongside fossils of plants known for their ability to withstand extremely cold temperatures.

(D) The number of fossils found together indicates herds of dinosaurs so large that they would need to migrate to find a continual food supply.

(E) Experts on prehistoric climatic conditions believe that winter temperatures in the prehistoric northern arctic were not significantly different from what they are today.

ywilfred · Accepted Answer

(A) Todayâ€™s reptiles are generally confined to regions of temperate or even tropical climates. 
- This sentence doesn't help us say some dinosaurs are not warm-blooded. It merely restates a fact given in the passage "cold blooded animals would freeze to death" when it says today's reptils are generally confined to regions of temperate/tropical climate.

(B) The fossils show the arctic dinosaurs to have been substantially smaller than other known species of dinosaurs. 
- Out of scope.

(C) The arctic dinosaur fossils were found alongside fossils of plants known for their ability to withstand extremely cold temperatures. 
- Still can't disprove the researcher's conclusion

(D) The number of fossils found together indicates herds of dinosaurs so large that they would need to migrate to find a continual food supply. 
- This is the answer. The dinosaurs that died might have been migrating to find a food supply (meaning they just happened to pass by the arctic and died there because reptiles would freeze to death in such cold climates) as opposed to living at the arctic.

(E) Experts on prehistoric climatic conditions believe that winter temperatures in the prehistoric northern arctic were not significantly different from what they are today.
- Doesn't tell us a thing apart from the climate being similar

D it is.

jpv · Answer

agree with (D)..

Argument can be easily weakened if we show that Dinosaurs move from some other place. (D) does that.

MoscowFuturist · Answer

D of course. E only strengthens the researches' hypotheses.

anandnk · Answer

not much to explain here.

(D) for me.
The cold-blooded dinos started migrating, got stuck in the arctic reagion, and became deadmeat.

Pronz · Answer

OFFICIAL EXPLANATION

Dinosaur fossils in northern arctic + Only warm-blooded animals can withstand arctic winters  Some dinosaurs were warm-blooded. What are the gaps in this argument? For one, perhaps the winters may have been different when the dinosaurs were around. Perhaps arctic winters weren't as cold back then as they are now, and cold-blooded dinosaurs could have survived. For another, perhaps the dinosaurs migrated north in the warmer summer, and migrated to warmer areas in the south for the winter. In this case, they wouldn't need to survive arctic winters.

(A) Does this generalization have any impact on our conclusion? No. The fact that the reptiles generally live in temperate or tropical climates has no impact on our argument-this doesn't mean reptiles don't live in cold climates. Furthermore, we're assuming a lot in connecting the behavior of reptiles today with the behavior of dinosaurs.

(B) It's unclear what relevance the size of the dinosaurs has for this argument. So what if they were small? Perhaps you can imagine some relationship between size and heat-retention. However, if you need to add another premise to justify an answer, that answer is incorrect. However, that requires assumptions that go too far beyond the text.

(C) If this is true, it would seem the dinosaurs died during very cold temperatures. It supports the idea, perhaps, that the dinosaurs died in the winter. That would make it so the author's argument sounds better, and we're looking to weaken! We can eliminate this answer because it plays a reverse role. By the way, we can also eliminate this answer because it doesn't actually indicate whether these plants (and thus the dinosaurs) actually died in extremely cold temperatures; we simply know that these plants were capable of withstanding cold temperatures. If you noticed this, perhaps you also noticed that this answer has no direct bearing on the conclusion-that some dinosaurs may have been warm-blooded. It's often true that answers are wrong for multiple reasons.

(D) These herds migrated. If they migrated, perhaps they were in the north only during the summer months. Notice how this answer helps to break the bond between premise and conclusion. Thus this answer weakens the author's argument by deflecting the impact of evidence the author uses to prove that there were warmblooded dinosaurs.  (D) is correct.

(E) This is a very tempting answer. Of all the choices, this one addresses a gap in the argument most directly. However, notice that this is an answer that would strengthen the argument. It's another answer that's the opposite of what we're looking for.

Mavisdu1017 · Answer

Hello expert, 
I could not understand why C is wrong, besides, I think C is much more direct than D.
Passage says “only warm-blooded animals could have withstood the frigid temperatures”, but dinos can not withstand by themselves, so they need plants known for their ability to deal with the cold weather, so dinos are not warm blooded (common sense warm blood animals do not need plant to withstand cold weather). Weaken the conclusion.

While D says dino would need to migrate to find a continual food supply, but passage never mentions “there is more food supply in northern arctic”, so we must think too much, so I think this choice is not as direct enough as C.
Pls help, and much thanks.

RonTargetTestPrep · Answer

I don't really understand your reasoning here.

Perhaps the phrase "warm-blooded" is the problem? "Warm-blooded" animals—including humans—have metabolic processes that give off heat, and therefore have a body temperature that's higher than the ambient temperature of their surroundings.
"Cold-blooded" animals, by contrast, warm up or cool off along with their surroundings. Since blood is water-based, cold-blooded animals can't live where temps dip below freezing—their blood would literally freeze in their veins 😳 and they'd all die.

Plants have nothing to do with the distinction between warm-blooded and cold-blooded animals. There are warm-blooded animals that eat plants, and there are also cold-blooded animals that eat plants.
The significance of choice C is that these plants could have been a food supply for our hypothetical arctic dinosaurs. This choice makes it more reasonable that dinosaurs could have survived up there; therefore it  strengthens  the researchers' argument!

The passage definitely does not say that. There's very little biomass of any kind way up there, whether it's potential dinosaur food or not.

Choice D, however, says that big herds of dinosaurs  had to keep wandering around, hoping they'd find food . Of course, they wouldn't have any idea whether heading in any particular direction would actually lead them to food—they just had to get lucky!
According to choice D, those fossils could have come from a herd of dinosaurs that made an unfortunate choice, headed in the wrong direction, ended up in the arctic, and starved and/or froze to death (whichever came first). Yikes.

RonTargetTestPrep · Answer

This is wrong, by the way. The giant tegu lizard, which is definitely not extinct (there are plenty of tegu lizards running around South America, and  one of them even got loose in Florida last year ), is a reptile that is warm-blooded. 
The fact-checking team must have had the day off ¯\_(ツ)_/¯

Elite097 · Answer

KarishmaB   MartyMurray  @experts pls explain how choice D would weaken the conclusion that dinosaurs are warm blooded

MartyMurray · Answer

The researchers have concluded the following:

at least some dinosaurs might have been warm-blooded

The support for their conclusion is the following:

The recent discovery of dinosaur fossils in the northern arctic

and

only warm-blooded animals could have withstood the frigid temperatures that are characteristic of arctic winters

Notice that the "frigid temperatures" that only warm-blooded animals could have withstood are "characteristic of arctic winters."

Now, here's choice (D):

(D) The number of fossils found together indicates herds of dinosaurs so large that they would need to migrate to find a continual food supply.

Notice that what choice (D) says is basically that the dinosuaurs in question migrated regularly.

So, what does that information mean to us? It means that the dinosaurs may have been in the arctic but may not have been warm blooded because they migrated regularly. So, they didn't remain in the same place for extended periods of time and thus may have migrated to the arctic during warmer months and migrated to other areas in winter months.

So, in short, the fact that the dinosaurs likely migrated weakens the case for the conclusion by indicating that they did not necessarily survive the arctic winters and thus indicating that it's quite possible that they were not warm blooded.

VerbalBot · Answer

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