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.
The article and lecture both deal with how agnostids my have lived. Whilst the author proposes three possible hypotheses and provides evidence to support them, the lecturer contradicts his arguments respectively.
First, the author states that agnostids might have lived as strong swimmers and active predators, since many other types of primitive arthropods have been proved to be free-swiming predators. Furthermore, it is asserted in the article that even for small agnostids, there are plenty of smaller organisms in the ancient ocean for them to hunt. In contrast, the professor argues that predators usually have large eyes and vision, while agnostids have tiny eyes and poor visions, some even are blind. Furthermore, she also rule out the possibility that agnostids may have other sensory organs as there is no evidence has been obtained so far.
Second, according to the article, agnostids as many other types of arthropods might live on the seafloor, where they could find dead organisms or bacteria to survive. However, the lecturer again questions this argument by pointing out that agnostids live in multiple geological areas, indicating that they may move very fast, which is opposite to seafloor dwellers that usually move very slow and live in very small geological area.
Last, the author posits that agnostids could be parasites living on fish or other larger organisms because many types of arthropods live this way. As opposed to the writer, the speaker mentions that the population of parasites is often very small to avoid killing the hosts. Unlike parasites, agnostids live in large group.
As we can see, the author and lecturer hold very different views on possible ways that agnostids may have lived.
| Post date | Users | Rates | Link to Content |
|---|---|---|---|
| 2023-09-05 | YasamanEsml | 86 | view |
| 2023-06-19 | Vivian Chang | 76 | view |
| 2023-02-07 | reza_fattahi | 73 | view |
| 2023-01-30 | reza_fattahi | 86 | view |
| 2023-01-30 | reza_fattahi | 75 | view |
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Grammar and spelling errors:
Line 3, column 521, Rule ID: HE_VERB_AGR[3]
Message: The pronoun 'she' must be used with a third-person verb: 'rules'.
Suggestion: rules
...e even are blind. Furthermore, she also rule out the possibility that agnostids may ...
^^^^
Transition Words or Phrases used:
also, first, furthermore, however, if, may, second, so, well, while, in contrast
Attributes: Values AverageValues Percentages(Values/AverageValues)% => Comments
Performance on Part of Speech:
To be verbs : 10.0 10.4613686534 96% => OK
Auxiliary verbs: 8.0 5.04856512141 158% => OK
Conjunction : 9.0 7.30242825607 123% => OK
Relative clauses : 12.0 12.0772626932 99% => OK
Pronoun: 21.0 22.412803532 94% => OK
Preposition: 28.0 30.3222958057 92% => OK
Nominalization: 4.0 5.01324503311 80% => OK
Performance on vocabulary words:
No of characters: 1464.0 1373.03311258 107% => OK
No of words: 277.0 270.72406181 102% => OK
Chars per words: 5.28519855596 5.08290768461 104% => OK
Fourth root words length: 4.07962216107 4.04702891845 101% => OK
Word Length SD: 2.56438167648 2.5805825403 99% => OK
Unique words: 156.0 145.348785872 107% => OK
Unique words percentage: 0.563176895307 0.540411800872 104% => OK
syllable_count: 458.1 419.366225166 109% => OK
avg_syllables_per_word: 1.7 1.55342163355 109% => OK
A sentence (or a clause, phrase) starts by:
Pronoun: 2.0 3.25607064018 61% => OK
Article: 8.0 8.23620309051 97% => OK
Subordination: 4.0 1.25165562914 320% => Less adverbial clause wanted.
Conjunction: 0.0 1.51434878587 0% => OK
Preposition: 3.0 2.5761589404 116% => OK
Performance on sentences:
How many sentences: 12.0 13.0662251656 92% => OK
Sentence length: 23.0 21.2450331126 108% => OK
Sentence length SD: 53.1639889608 49.2860985944 108% => OK
Chars per sentence: 122.0 110.228320801 111% => OK
Words per sentence: 23.0833333333 21.698381199 106% => OK
Discourse Markers: 6.66666666667 7.06452816374 94% => OK
Paragraphs: 5.0 4.09492273731 122% => OK
Language errors: 1.0 4.19205298013 24% => OK
Sentences with positive sentiment : 1.0 4.33554083885 23% => More positive sentences wanted.
Sentences with negative sentiment : 5.0 4.45695364238 112% => OK
Sentences with neutral sentiment: 6.0 4.27373068433 140% => OK
What are sentences with positive/Negative/neutral sentiment?
Coherence and Cohesion:
Essay topic to essay body coherence: 0.158454703418 0.272083759551 58% => OK
Sentence topic coherence: 0.0680450567336 0.0996497079465 68% => OK
Sentence topic coherence SD: 0.0478474464938 0.0662205650399 72% => OK
Paragraph topic coherence: 0.0947576855089 0.162205337803 58% => OK
Paragraph topic coherence SD: 0.0268415130888 0.0443174109184 61% => OK
Essay readability:
automated_readability_index: 15.0 13.3589403974 112% => OK
flesch_reading_ease: 39.67 53.8541721854 74% => OK
smog_index: 3.1 5.55761589404 56% => Smog_index is low.
flesch_kincaid_grade: 13.4 11.0289183223 121% => OK
coleman_liau_index: 13.7 12.2367328918 112% => OK
dale_chall_readability_score: 8.77 8.42419426049 104% => OK
difficult_words: 70.0 63.6247240618 110% => OK
linsear_write_formula: 10.5 10.7273730684 98% => OK
gunning_fog: 11.2 10.498013245 107% => OK
text_standard: 14.0 11.2008830022 125% => 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.