A closer look at Question #3
Rebekah wrote:
Can someone explain the third question? I got it right, but I spent almost 3 mins on this one. I had difficulties in locating where should I refer to answer this question.
It can be inferred that on the basis of the 1981 discovery of conodont remains, paleontologists could draw which of the following conclusions?
A The earliest vertebrates were sedentary suspension feeders.
B Ostracoderms were not the earliest vertebrates.
C Defensive armor preceded jaws among vertebrates.
D Paired eyes and adaptations for activity are definitive characteristics of vertebrates.
E Conodonts were unlikely to have been predators.
I found the discovery in p1 and p3. p1 just states that the discovery changes the views scientists hold about the development of vertebrate animals. p3 seems talk about the discovery(in a vague and subtle way, there is no obvious link between the discovery talked about in p1)
Cheers!
Your approach to this question was sound! It's a legitimately tough question, and difficult to answer without a clear read on the passage structure
and process of elimination.
Quote:
It can be inferred that on the basis of the 1981 discovery of conodont remains, paleontologists could draw which of the following conclusions?
The only place this discovery is explicitly mentioned is in P1, but (as you know) this isn't a situation where there's some immediate factoid that we see directly connected to the year 1981. Instead, we see this big-picture statement:
"However, since the 1981 discovery of fossils preserving not just the phosphatic elements but also other remains of the tiny soft-bodied animals (also called conodonts) that bore them, scientists' reconstructions of the animals' anatomy have had important implications for hypotheses concerning the development of the vertebrate skeleton."
This doesn't point us to something that happened in 1981. Instead, the significance of this line is
why the author brings up this discovery: To call into question the existing hypotheses about why the vertebrate skeleton evolved.
OK, so let's think about this structurally. P1 tells us that the conodont discovery set up scientists (and us, the readers) to reconsider two hypotheses. P2 is all about presenting those hypotheses (which existed prior to the discovery and did not use conodonts as evidence), so we're not going to find the answer there.
But the purpose of P3 is to tell us that the hypothesis of aggressive evolution seems to be correct. And P3 delivers this statement based on the discovery of conodont remains:
"The stiffening notochord...V-shaped muscle blocks...and posterior tail fins help to identify conodonts as among the most primitive of vertebrates. The lack of any mineralized structures...indicates that conodonts were more primitive than the armored jawless fishes such as the ostracoderms. It now appears that the hard parts that first evolved in the mouth of an animal improved its efficiency as a predator, and that aggression rather than protection was the driving force behind the origin of the vertebrate skeleton."
All right! The 1981 discovery triggered a new debate over the origin of the vertebrate AND placed conodonts as one of the earliest examples of vertebrate evolution being driven by aggression.
Let's start eliminating:
Quote:
A. The earliest vertebrates were sedentary suspension feeders.
Sedentary suspension feeders were mentioned in P2 as potential evidence for vertebrate evolution being defensive. It's a thing that was mentioned in the passage, but it's not a statement that we can infer
on the basis of the 1981 discovery of conodont remains. Eliminate (A).
Quote:
B. Ostracoderms were not the earliest vertebrates.
This looks good! P3 specifically tells us that conodonts were vertebrates AND were
more primitive than ostracoderms. This would imply that Ostracoderms were not the earliest vertebrates, because they were predated by conodonts. Let's keep choice (B) around and keep moving.
Quote:
C. Defensive armor preceded jaws among vertebrates.
Nope. Like choice (A), this is not a statement that we can infer
on the basis of the 1981 discovery of conodont remains. It's a tempting choices, but we can eliminate (C) just like we eliminated (A).
Quote:
D. Paired eyes and adaptations for activity are definitive characteristics of vertebrates.
Like (A) and (C), this choice is tempting but it's not a fact that we can infer on the basis of the 1981 discovery. Eliminate (D).
Quote:
E. Conodonts were unlikely to have been predators.
Choice (E) is totally off the rails (off the spine?). The entire point of P3 is that conodonts were evolved to be predators. This is the opposite of what this choice says, so let's eliminate (E), too.
(B) is the only choice that directly answers the question and is backed up by our understanding of the 1981 discovery's importance.
I hope this helps clarify how to stay ahead of this question! Whether or not it increases your appreciation of conodonts is up to you. I do hear rumors that they taste like chicken... :tongue_opt2
"P2 is all about presenting those hypotheses (which existed prior to the discovery and did not use conodonts as evidence)"
Which `s word/phase specifically mentioned that P2 were the hypotheses before the discovery 1981?
close
14 Apr 2020, 04:02
