Recent research in an old quarry uncovered tracks from several Stegosa

Question

Recent research in an old quarry uncovered tracks from several Stegosaurus dinosaurs, and the tracks all headed in the same direction. A second set of tracks from the same quarry shows one instance of overlapping footprints, where a juvenile Stegosaurus footprint was stepped on by an adult Stegosaurus. From this one can infer that Stegosauruses most likely traveled in multiple-age herds and that adults of this species cared for their young.

Which of the following is an assumption on which the argument depends?

(A) Many modern herd animals care for their young.
(B) Male and female adult Stegosauruses traveled together in the herd.
(C) No tracks from dinosaurs other than Stegosaurus were found in the vicinity of the Stegosaurus tracks.
(D) The adult dinosaur print was made at the time the juvenile print was made.
(E) The existence of parental care has been established for other dinosaur species.

MartyMurray · Answer

Recent research in an old quarry uncovered tracks from several Stegosaurus dinosaurs, and the tracks all headed in the same direction. A second set of tracks from the same quarry shows one instance of overlapping footprints, where a juvenile Stegosaurus footprint was stepped on by an adult Stegosaurus. From this one can infer that Stegosauruses most likely traveled in multiple-age herds and that adults of this species cared for their young.

The conclusion of the argument is the following:

From this one can infer that Stegosauruses most likely traveled in multiple-age herds and that adults of this species cared for their young.

The support for the conclusion is the following:

A second set of tracks from the same quarry shows one instance of overlapping footprints, where a juvenile Stegosaurus footprint was stepped on by an adult Stegosaurus.

We see that the reasoning is basically that, since a juvenile Stegosaurus footprint was stepped on by an adult Stegosaurus, one can infer that juveniles and adults likely traveled together and that adults cared for juveniles.

One aspect of the argument that we may notice is that it jumps from the fact that a juvenile footprint was stepped on by an adult to a conclusion about traveling together and adults caring for juveniles. Both parts of the conclusion, the traveled together part and the adults cared for juveniles part, are rather different in terms of topic from the simple fact that the footprint one Stegosaurus was stepped on by another Stegosaurus.

Which of the following is an assumption on which the argument depends?

This is an Assumption question, and the correct answer will be a statement that must be true for the premise to effectively support the conclusion.

(A) Many modern herd animals care for their young.

Regardless of whether many modern herd animals care for their young, it could still make sense to conclude from the evidence that adult Stegosauruses cared for their young.

After all, even if few modern animals care for their young, Stegosauruses may have.

Eliminate.

(B) Male and female adult Stegosauruses traveled together in the herd.

Regardless of whether male and female Stegosauruses traveled together, it could still make sense to conclude from fact that footprints of adult and juvenile Stegosauruses were found together that Stegosauruses of different ages traveled together.

So, this choice doesn't have to be true for the argument to work.

Eliminate.

(C) No tracks from dinosaurs other than Stegosaurus were found in the vicinity of the Stegosaurus tracks.

Even if this choice is not true and some tracks from dinosaurs other than Stegosaurus were found in the vicinity of the Stegosaurus tracks, the fact that juvenile and adult Stegosaurus footprints were found together still supports the conclusion that adult Stegosauruses traveled together with and cared for their young.

Eliminate.

(D) The adult dinosaur print was made at the time the juvenile print was made.

This choice is interesting.

As discussed above, the argument jumps from the fact that adult and juvenile footprints were found together to the conclusion that one can infer that adults and juveniles likely traveled together and adults cared for juveniles.

What the argument assumes in doing so is that the the adult and juvenile prints were made at the same time.

After all, if this choice is not true and the adult print was NOT made at the time the juvenile print was made, then the fact that the prints were found together doesn't mean that the Stegosauruses traveled together. Rather, in that case, they may not have traveled together, and the prints may be together simply because different Stegosauruses were at the same place at different times.

So, for the fact about the prints being together to effectively support the conclusion, this choice has to be true.

Keep.

(E) The existence of parental care has been established for other dinosaur species.

Regardless of whether dinosaurs of other species cared for their young, Stegosauruses may have.

So, even if this choice is not true, it's still reasonable to conclude from that the fact that adult and juvenile Stegosaurus footprints were found together that Stegosauruses cared for their young.

Eliminate.

Correct answer:   D

isteducimus · Answer

isn't option D already been stated in the stem - "...where a juvenile Stegosaurus footprint was stepped on by an adult Stegosaurus." It is a statement from the question itself, how can it be as assumption? It seemed more like of an reiteration of a line from question, instead of some underlying assumption. Please help Sir!

egmat · Answer

isteducimus  If I can help, here is the key distinction you're missing-

What the stimulus tells us: An adult footprint is  physically on top of  a juvenile footprint.

What the stimulus does  NOT  tell us:  When  these two prints were made relative to each other.

Think About This Scenario:

Imagine you walk across wet cement and leave your footprint. Now imagine I come by 3 days later and step on your dried footprint. Would this prove we were walking together? Of course not! We'd need to have been there at roughly the  same time  for that conclusion.

Why The Timing Assumption Matters:

The argument concludes that Stegosauruses:
 
 Traveled in multi-age herds (together) 
 Adults cared for their young

For this conclusion to work, the adult and juvenile must have been traveling  together  - which requires them to be there at approximately the  same time .

If the adult stepped on the juvenile's print hours, days, or weeks later, it tells us nothing about herding behavior or parental care. They could have been completely separate individuals who just happened to cross the same spot at different times.

Here's the Strategic Framework for You - The "Time Gap Test":

When you see a CR argument that concludes a  relationship  or  connection  between two things based on physical evidence, always ask: "Does the evidence prove they were connected  in time , or just  in space ?"

This same logic appears in arguments about:
- Archaeological findings suggesting cultures interacted
- Crime scene evidence linking suspects
- Scientific observations inferring cause-and-effect

You can practice similar questions  here  (you'll find OG questions here) - select  Critical Reasoning  and choose Easy/Medium level questions focusing on  assumption types .

Recent research in an old quarry uncovered tracks from several Stegosa

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GMAT Critical Reasoning (CR) Questions

Recent research in an old quarry uncovered tracks from several Stegosa

Prep Toolkit

615 to 715 in 15 Days (Ria's Strategies)

More than Quant/Verbal Abilities: Speed vs. Accuracy

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Perfect 805 Score Debrief by Julia

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