Agnostids were a group of marine animals that became extinct about 450 million years ago. Agnostid fossils can be found in rocks in many areas around the world. From the fossil remains, we know that agnostids were primitive arthropods—relatives of modern-day insects. However, the fossil information does not allow paleontologists to determine with certainty what agnostids ate or how they behaved. There are several different theories about how agnostids may have lived.
Free-Swimming Predators
First, the agnostids may have been free-swimming predators that hunted smaller animals. It is known that other types of primitive arthropods were strong swimmers and active predators, so it is reasonable that the agnostids may have lived that way as well. And while the agnostids were small, sometimes just six millimeters long, there were plenty of smaller organisms in the ancient ocean for them to prey on.
Seafloor Dwellers
Second, they may have dwelled on the seafloor. Again, there are examples of other types of primitive arthropods living this way, so it is possible that agnostids did too. On the seafloor they would have survived by scavenging dead organisms or by grazing on bacteria.
Parasites
Third, there is the possibility that the agnostids were parasites, living on and feeding off larger organisms. One reason that this seems possible is that there are many species of modern-day arthropods that exist as parasites, such as fleas, ticks, and mites. The agnostids might have lived on primitive fish or even on other, larger arthropods.
Both the reading passage and the lecture discuss the ways that agnostids may have lived. The passage proposes three theories to explain how agnostids lived. However, the professor of the lecture casts doubt on all the theories mentioned in the passage.
First of all, the passage states that the agnositds may have been free-swimming predators that hunted smaller animals, since other types of primitive arthropods were strong swimmers and predators. Nevertheless, the professor counters the passage by arguing that those arthropods had large and well-developed eyes to locate preys, yet the agnositds' eyes are very tiny and almost blind. Moreover, they did not have other sensation organs that could help them target preys.
Secondly, the passage claims that the agnostids may have dwelled on the seafloor, since, again, other types of primitive arthropods living this way. Notwithstanding, the professor disagrees with the passage. She mentions that seafloor dwellers move slowly, so they usually dwelled in small geological area. However, the agnostid' fossils appeared in multiple geological areas, which means that they could move in large distances.
Finally, the passage suggests that it is possible that the agnostids were parasites, since there are many species of modern-day arthropods that exist as parasites. However, the professor refutes the passage by pointing out that parasites can not have large population, or they will kill the host easily. Yet there are vast amount of agnostid fossils, thus, it is unlikely that they were parasites.
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| 2023-09-05 | YasamanEsml | 86 | view |
| 2023-06-19 | Vivian Chang | 76 | view |
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Grammar and spelling errors:
Line 7, column 324, Rule ID: THERE_RE_MANY[3]
Message: Possible agreement error. Did you mean 'amounts'?
Suggestion: amounts
...ill the host easily. Yet there are vast amount of agnostid fossils, thus, it is unlike...
^^^^^^
Transition Words or Phrases used:
finally, first, however, may, moreover, nevertheless, second, secondly, so, thus, well, first of all
Attributes: Values AverageValues Percentages(Values/AverageValues)% => Comments
Performance on Part of Speech:
To be verbs : 9.0 10.4613686534 86% => OK
Auxiliary verbs: 7.0 5.04856512141 139% => OK
Conjunction : 7.0 7.30242825607 96% => OK
Relative clauses : 14.0 12.0772626932 116% => OK
Pronoun: 24.0 22.412803532 107% => OK
Preposition: 20.0 30.3222958057 66% => OK
Nominalization: 2.0 5.01324503311 40% => More nominalizations (nouns with a suffix like: tion ment ence ance) wanted.
Performance on vocabulary words:
No of characters: 1323.0 1373.03311258 96% => OK
No of words: 240.0 270.72406181 89% => More content wanted.
Chars per words: 5.5125 5.08290768461 108% => OK
Fourth root words length: 3.93597934253 4.04702891845 97% => OK
Word Length SD: 2.65334890594 2.5805825403 103% => OK
Unique words: 136.0 145.348785872 94% => More unique words wanted.
Unique words percentage: 0.566666666667 0.540411800872 105% => OK
syllable_count: 399.6 419.366225166 95% => OK
avg_syllables_per_word: 1.7 1.55342163355 109% => OK
A sentence (or a clause, phrase) starts by:
Pronoun: 3.0 3.25607064018 92% => OK
Article: 9.0 8.23620309051 109% => OK
Subordination: 2.0 1.25165562914 160% => OK
Conjunction: 3.0 1.51434878587 198% => OK
Preposition: 2.0 2.5761589404 78% => OK
Performance on sentences:
How many sentences: 13.0 13.0662251656 99% => OK
Sentence length: 18.0 21.2450331126 85% => The Avg. Sentence Length is relatively short.
Sentence length SD: 42.933552623 49.2860985944 87% => OK
Chars per sentence: 101.769230769 110.228320801 92% => OK
Words per sentence: 18.4615384615 21.698381199 85% => OK
Discourse Markers: 7.69230769231 7.06452816374 109% => OK
Paragraphs: 4.0 4.09492273731 98% => OK
Language errors: 1.0 4.19205298013 24% => OK
Sentences with positive sentiment : 4.0 4.33554083885 92% => OK
Sentences with negative sentiment : 4.0 4.45695364238 90% => OK
Sentences with neutral sentiment: 5.0 4.27373068433 117% => OK
What are sentences with positive/Negative/neutral sentiment?
Coherence and Cohesion:
Essay topic to essay body coherence: 0.177099699178 0.272083759551 65% => OK
Sentence topic coherence: 0.0654793821734 0.0996497079465 66% => OK
Sentence topic coherence SD: 0.0608756308325 0.0662205650399 92% => OK
Paragraph topic coherence: 0.109107878382 0.162205337803 67% => OK
Paragraph topic coherence SD: 0.0505761650734 0.0443174109184 114% => OK
Essay readability:
automated_readability_index: 13.8 13.3589403974 103% => OK
flesch_reading_ease: 44.75 53.8541721854 83% => OK
smog_index: 3.1 5.55761589404 56% => Smog_index is low.
flesch_kincaid_grade: 11.5 11.0289183223 104% => OK
coleman_liau_index: 14.68 12.2367328918 120% => OK
dale_chall_readability_score: 8.81 8.42419426049 105% => OK
difficult_words: 65.0 63.6247240618 102% => OK
linsear_write_formula: 10.5 10.7273730684 98% => OK
gunning_fog: 9.2 10.498013245 88% => OK
text_standard: 11.0 11.2008830022 98% => OK
What are above readability scores?
---------------------
Rates: 80.0 out of 100
Scores by essay e-grader: 24.0 Out of 30
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Note: the e-grader does NOT examine the meaning of words and ideas. VIP users will receive further evaluations by advanced module of e-grader and human graders.