Recently, a team of scientists digging through a tar pit unearthed

Question

Recently, a team of scientists digging through a tar pit unearthed a jawbone fossil. Initially, the team hypothesized that the jawbone came from a young gomphothere, a now extinct distant relative of the elephant, since the teeth were those of a juvenile. The gomphothere, however, is known for its large molars, and the teeth on the jawbone would not allow enough room for the molars of an adult gomphothere to fit. Based on this evidence, the scientists conclude that the jawbone fossil provides evidence of a distinct species closely related to the gomphothere.

Which of the following, if true, would best provide evidence showing that the conclusion above is possibly flawed?

(A) The manner in which teeth grow provide sufficient evidence for the accurate classification of a bygone species.

(B) In order for the molars of an adult gomphothereto emerge, several juvenile teeth are first forced out of the gums to accommodate the molars.

(C) The molars of an adult mastodon, a close relative of the gomphothere, are similar in size to those of an adult gomphothere.

(D) Many fossils exist that have yet to be conclusively attributed to any one species.

(E) The juvenile jawbone of a species related to a gomphothere is longer than the juvenile jawbone of a gomphothere.

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chandy123 · Answer

Answer: (B) In order for the molars of an adult gomphothere to emerge, several juvenile teeth are first forced out of the gums to accommodate the molars.

Explanation:

Understanding the Argument:
 • Premise: The jawbone had teeth that were juvenile in size and arrangement. However, the teeth on the jawbone wouldn’t leave enough room for the large molars of an adult gomphothere.
 • Conclusion: The jawbone is from a distinct species closely related to the gomphothere.

The scientists base their conclusion on the assumption that the juvenile teeth on the jawbone would persist into adulthood, preventing the emergence of the gomphothere’s characteristic large molars.

Analyzing the Answer Choices:

• (A): The manner in which teeth grow provides sufficient evidence for the accurate classification of a bygone species.
 • This is a general statement about teeth growth but does not address whether the juvenile teeth of a gomphothere are replaced by molars, which is the key point in the argument. It does not weaken the conclusion.
 • (B): In order for the molars of an adult gomphothere to emerge, several juvenile teeth are first forced out of the gums to accommodate the molars.
 • Correct. This directly challenges the argument by showing that the scientists may have overlooked a natural process in which juvenile teeth are replaced by adult molars. If true, the jawbone could still belong to a juvenile gomphothere, weakening the conclusion that it represents a distinct species.
 • (C): The molars of an adult mastodon, a close relative of the gomphothere, are similar in size to those of an adult gomphothere.
 • This provides a comparison but does not directly affect the argument about whether the jawbone belonged to a gomphothere or a distinct species.
 • (D): Many fossils exist that have yet to be conclusively attributed to any one species.
 • While this is true, it does not address the specific evidence or reasoning used in the argument about the jawbone.
 • (E): The juvenile jawbone of a species related to a gomphothere is longer than the juvenile jawbone of a gomphothere.
 • This is irrelevant to the argument, as it focuses on jawbone length rather than the relationship between juvenile teeth and adult molars.

Conclusion:

The best evidence showing that the conclusion may be flawed is (B), as it challenges the assumption that the juvenile teeth in the jawbone would persist into adulthood, which is central to the argument.

partay1106 · Answer

Can somebody please help me understand if there is any relevance of distinguishing between the words "adult" and "young"  gomphothere ? The question states that the jawbone fossil seems to be of a YOUNG gomphothere (juvenile teeth) so why are we relating it to how the large molars of an ADULT gomphothere can fit into this jawbone as a flaw? Shouldn't the molars of a YOUNG gomphothere also be considered in this case? Or is it clear from the passage that the molars only emerge in the  gomphothere after a certain age (only adults)? Is it not possible that the molars of a YOUNG gomphothere are slightly smaller than the molars of an ADULT gomphothere to easily fit into the same jawbone fossil discovered as it is hypothesized to be of a YOUNG gomphothere?

Matty101 · Answer

You are not wrong, but there is not specific mention of the molars for a young gomphothere, so when I go through a question like this, I just don't even entertain the possibility that the molars exist at the age. It is possible that the molars of a young gomphothere are only slightly smaller, but that is an assumption we would need to make.

chandy123 · Answer

• The passage’s logic hinges on comparing what the juvenile fossil’s jaw could eventually accommodate with what is known about adult gomphothere dentition.
• For a juvenile gomphothere, you start with smaller, juvenile teeth. As the animal matures, these are replaced by large adult molars that fit into the jaw as it grows and changes.
• The scientists look at the fossil’s jawbone and juvenile teeth and note that, given the structure, there would not be enough room for the large adult molars that a gomphothere would later develop.
• In other words, they are not just considering the size of the current juvenile teeth. They are considering whether the jawbone, as it grows from the juvenile stage, would have the capacity to eventually accommodate the much larger adult molars characteristic of gomphotheres.
• The conclusion that this fossil belongs to a distinct but related species comes from the assumption that there is a known developmental path for gomphotheres: juvenile teeth give way to large adult molars that must fit in a certain way. If the fossilized jaw cannot support that future adult configuration, it challenges the identification as a juvenile gomphothere.
• Thus, the distinction between juvenile and adult is crucial: the scientists are not simply comparing the juvenile fossil to a young gomphothere’s current teeth. Rather, they are considering whether the fossil jaw could ever grow to accommodate the adult molars known to emerge later in a gomphothere’s life cycle. If it cannot, that suggests it is not a gomphothere at all, hence their conclusion that it might represent a different species.

Bunuel · Answer

Official Explanation

Premise #1 – Fossil of a jawbone is that of a juvenile animal (one theory is that it is the remains of a gomphothere)

Premise #2 - Jawbone does not have enough space to accommodate big molars (the gomphotheres are known for this).

Conclusion: Jawbone not that of a gomphothere.

(A) is tempting since it is an assumption upon which the argument rests. However, we are looking for a weakener.

(B) provides evidence that the lack of space on the jawbone of a juvenile gomphothere is not a reason to discount the theory that the jawbone is that of a gomphothere. Before gomphotheres become adults, teeth are forced out of the jawbone and that allows room for the massive molars to grow.

(C) provides information that, on the basis of the logic in the conclusion, discounts the mastodon as a viable candidate for the fossil. In other words, an adult mastodon also has large molars that wouldn’t be able to fit on the jawbone fossil. This does not weaken the conclusion, since yet another species may still have existed.

(D) does not specifically address the connection between the jawbone and the molars.

(E) The conclusion is focused on the lack of space on the jawbone fossil for big molars. A possible correct answer could be that there is a similar species that does not have as large as molar as the gomphothere. That another species has an even longer jawbone than the gomphothere does not point to the fossil at all. The fossil is discounted as coming from a gomphothere, because there is not enough space for the molars not because the jawbone is not longer enough.

Recently, a team of scientists digging through a tar pit unearthed

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Recently, a team of scientists digging through a tar pit unearthed

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