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OG Conodonts, the spiky phosphatic remains

This topic has 4 expert replies and 3 member replies
AbeNeedsAnswers Master | Next Rank: 500 Posts Default Avatar
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OG Conodonts, the spiky phosphatic remains

Post Sat Aug 19, 2017 2:07 pm
Elapsed Time: 00:00
  • Lap #[LAPCOUNT] ([LAPTIME])
    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
    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
    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.

    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-
    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
    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.
    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
    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,
    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
    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.

    514) 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

    515) 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

    516) 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.

    Q514: D
    Q515: E
    Q516: B

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    NandishSS Master | Next Rank: 500 Posts Default Avatar
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    Post Thu Sep 21, 2017 9:23 pm
    Hi Dave/Guru/Experts,

    Tried my best to map the above passage. Please let me know is this right?

    Conodonts-->controversial of fossils--> implications for hypotheses concerning the development of the vertebrate skeleton.

    defensive development --> easy prey for numerous invertebrate carnivores-->But Teeth were more
    primitive than external armor according to this view, and the earliest vertebrates were predators.

    The lack of any mineralized structures --> jawless fishes such as the ostracoderms --> hard parts that first evolved in the mouth --> defense

    Can you please help me with these questions?

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    NandishSS Master | Next Rank: 500 Posts Default Avatar
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    Post Thu Sep 21, 2017 9:30 pm
    514) 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

    Why is it not C? Where is it mentioned?

    515) 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

    Is second paragraph not a comparison or contrast? defensive development -- earliest vertebrates were predators or not?

    516) 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.

    How to deal with inference question and which are the lines to look back?

    bounce87 Junior | Next Rank: 30 Posts Default Avatar
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    16 messages
    Post Wed Sep 27, 2017 10:18 am
    some expert advice on this topic would be helpful!

    Post Wed Sep 27, 2017 11:10 am
    NandishSS wrote:
    Hi Dave/Guru/Experts,

    Tried my best to map the above passage. Please let me know is this right?

    Conodonts-->controversial of fossils--> implications for hypotheses concerning the development of the vertebrate skeleton.

    defensive development --> easy prey for numerous invertebrate carnivores-->But Teeth were more
    primitive than external armor according to this view, and the earliest vertebrates were predators.

    The lack of any mineralized structures --> jawless fishes such as the ostracoderms --> hard parts that first evolved in the mouth --> defense

    Can you please help me with these questions?
    The gist is of this passage is that there's a debate between two camps regarding the evolution of vertebrates. The traditionalists believe that bony scales (protection) came first. The alternative view is that teeth (predation) came. The new discovery favors the teeth (predation) hypothesis. That's the main thing you want to come away with.

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    Post Wed Sep 27, 2017 11:14 am
    Quote:
    514) 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
    In the second paragraph we're first given what the traditionalists believe: Thus, traditionalists argued, these animals developed coverings of bony scales or plates, and teeth were
    secondary features
    In other words, scales or plates came before teeth.

    The discovery of the conodonts undermined the traditionalist belief. Note the last line of the passage: 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.

    So teeth came first. The answer is D

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    Post Wed Sep 27, 2017 11:16 am
    Quote:
    515) 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
    The second paragraph first gives us the traditional belief. The structural clue that we're going to get a competing belief is the transition, "however." However, other paleontologists argued

    So we're getting two sides of an argument. The answer is E

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    Post Wed Sep 27, 2017 11:19 am
    Quote:
    516) 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.
    The key is this sentence in the third paragraph: 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.

    If the conodonts were primitive than the ostracoderms, then the conodonts came first. Thus, the ostracoderms could not have been the earliest vertebrates. The answer is B

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