• Conodonts, the spiky phosphatic remains (bones and teeth composed of calcium phosphate) of tiny marine animals that probably appeared about 520 million years ago, were once among the most

(5)

  • controversial of fossils. Both the nature of the organism to which the remains belonged and the function of the remains were unknown. However, since the 1981 discovery of fossils preserving not just the phosphatic elements but also other remains

(10)

  • 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.




(15)

  •    The vertebrate skeleton had traditionally been regarded as a defensive development, champions of this view postulating that it was only with the much later evolution of jaws that vertebrates became predators. The first vertebrates, which were soft-

(20)

  • bodied, would have been easy prey for numerous invertebrate carnivores, especially if these early vertebrates were sedentary suspension feeders. Thus, traditionalists argued, these animals developed coverings of bony scales or plates, and teeth were

(25)

  •     secondary features, adapted from the protective bony scales. Indeed, external skeletons of this type are common among the well-known fossils of ostracoderms, jawless vertebrates that existed from approximately 500 to 400 million years ago.

(30)

  • However, other paleontologists argued that many of the definitive characteristics of vertebrates, such as paired eyes and muscular and skeletal adaptations
         for active life, would not have evolved unless the

(35)

  • first vertebrates were predatory. Teeth were more primitive than external armor according to this view, and the earliest vertebrates were predators.





  • The stiffening notochord along the back of the    body, V-shaped muscle blocks along the sides,

(40)

  • and posterior tail fins help to identify conodonts as among the most primitive of vertebrates. The lack of any mineralized structures apart from the elements    in the mouth indicates that conodonts were more primitive than the armored jawless fishes such as the

(45)

  • 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.



Quite a tricky passage!


The first paragraph tells us that since the discovery 

  •  of fossils preserving not just the phosphatic elements but also other remains of the tiny soft-bodied animals,
  • scientists' reconstructions of the animals' anatomy have had important implications for hypotheses concerning the development of the vertebrate skeleton.


The second paragraph then talks about the traditional view- that 1st vertebrates were soft-bodied/ defensive 

And the view of other paleontologists- that 1st vertebrates were predators

Para 3- explains the evidence and what the author thinks-

 “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”



Qs 1-According to the passage, the anatomical evidence provided by the preserved soft bodies of conodonts led scientists to conclude that


A. conodonts had actually been invertebrate carnivores

B. conodonts' teeth were adapted from protective bony scales

C. conodonts were primitive vertebrate suspension feeders

D. primitive vertebrates with teeth appeared earlier than armored vertebrates

E. scientists' original observations concerning the phosphatic remains of conodonts were essentially correct


According to your map, the first paragraph says that the anatomical evidence provided by the preserved soft bodies of conodonts led to important implications on the development of vertebrates.  The next paragraph talks about the traditional view regarding vertebral skeleton and the view of other paleontologists. 

Line 35 gives us the answer to the question- option D


Option B is a trap option that can be located in the passage but is not the answer to the given question as option B talks about the traditional view. Not the hypothesis that the evidence led to.  


Please go through the question and options carefully and let me know if you need help with eliminating other choices.



2. The second paragraph in the passage serves primarily to


A. outline the significance of the 1981 discovery of conodont remains to the debate concerning the development of the vertebrate skeleton

B. contrast the traditional view of the development of the vertebrate skeleton with a view derived from the 1981 discovery of conodont remains

C. contrast the characteristics of the ostracoderms with the characteristics of earlier soft-bodied vertebrates

D. explain the importance of the development of teeth among the earliest vertebrate predators

E. present the two sides of the debate concerning the development of the vertebrate skeleton


1st para:

Some discovery of fossil remains led to important Implications of the development of vertebrates


2nd para: 

There is a group X that argued that 1st vertebrates were soft-bodied

There is another group Y that argued 1st vertebrates were predators


Options B and E are very very close. It is only the tone that will help us reach the answer. E is more accurate compared to B. 

The use of the second paragraph is simply to present two views. In the third paragraph, the author supports one view over the other. 

It is a very tricky question. Solving more such questions and making use of tone to answer a question will help you do better. 


Qs 3. 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.


Para 3 talks about the 1981 discovery of other remains of the tiny soft-bodied animals (also called conodonts). 

Let’s go back to para 3 and find out the answer to this question.


A talks about the traditional view. Eliminate 

B- B can be inferred from Line 40-

“The lack of any mineralized structures apart from the elements in the mouth indicates that conodonts were more primitive than the armored jawless fishes such as the ostracoderms.

C, D, and E cannot be inferred from the information given.