At the end of the Triassic period 200 million years ago, there was a mass-extinction event that caused the extinction of more than half of all living species. It was this extinction event that allowed dinosaurs to become the dominant species for the next 145 million years. We do not know exactly what happened that eliminated so many species in a relatively short period of time, but there are several possible explanations.
One theory involves the decline of sea levels. Near the end of the Triassic period, sea levels were fluctuating. When sea levels fall, the habitats for ocean populations that live in the shallows and land species that live on the coast are destroyed. The destruction of coastal and shallow-ocean species would have had a profound effect on food chains worldwide, leading to mass extinctions.
Another theory involves massive climate cooling. The end of the Triassic period was marked by widespread volcanic activity. The volcanoes released large amounts of sulfur dioxide (S02). A rise in atmospheric S02 is known to cause a lowering in global temperatures. Such climate change could have devastated many species and led to the extinctions.
The third theory involves an asteroid strike. Asteroids (objects from outer space) occasionally collide with Earth. When an asteroid hits Earth’s surface, it often displaces large amounts of soil and crushed rock, leaving behind a depression, or crater. The displaced debris is thrown up into the atmosphere where it can block out sunlight for many months or even a few years. A sufficiently massive asteroid impact at the end of the Triassic period may have blocked sunlight long enough for most plants to die and many animal species to then starve.
The article discusses about the probable theories explaining the mass-extinction event caused extinction of almost half of creatures which allowed dinosaurs to become dominant species for next 145 million years. However, the professor in the lecture refutes each of these theories and does not believe that any of them could be the main reason of this event.
First, the passage claims that there was remarkable fluctuations in the sea levels. The author states that during these fluctuations there might be serious decline in sea levels which destroyed the habitats for sallow-ocean and coastal species which had affected the food chains and leaded to mass extinction. However, the professor avers that these changes were not sudden, hence, those species were able to adapt to these gradual changes.
Second, the article states that sulfur dioxide (SO2) in the atmosphere which was released by widespread activity of volcanoes may contribute to this event since it cools the climate. Even though the professor agrees on that the SO2 can reduce the temperature she avers that SO2 remains relatively short time in the air and it combines with the water and falls back on the earth with rain.
Third, the reading claims that asteroids might have the biggest impact on the extinction. The author says that the collision of an asteroid with earth throws up large amounts of soil and dust into the air which blocks the sunlight for months and years and this will cause many of species to die. However, the professor states that if there were such a collision the scientist would be able to find the crater caused by the impact. She also avers that there was a crater but dates back to 12 million years before this event.
| Post date | Users | Rates | Link to Content |
|---|---|---|---|
| 2020-01-17 | nusybah | 80 | view |
| 2019-11-14 | M.S 2019 | 76 | view |
| 2019-10-24 | p0uya | 65 | view |
| 2019-10-24 | Seema Modak | 71 | view |
| 2019-10-08 | mahan vahab kashi | 80 | view |
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Transition Words or Phrases used:
also, but, first, hence, however, if, may, second, so, third
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 : 9.0 7.30242825607 123% => OK
Relative clauses : 16.0 12.0772626932 132% => OK
Pronoun: 25.0 22.412803532 112% => OK
Preposition: 36.0 30.3222958057 119% => OK
Nominalization: 4.0 5.01324503311 80% => OK
Performance on vocabulary words:
No of characters: 1432.0 1373.03311258 104% => OK
No of words: 288.0 270.72406181 106% => OK
Chars per words: 4.97222222222 5.08290768461 98% => OK
Fourth root words length: 4.11953428781 4.04702891845 102% => OK
Word Length SD: 2.41234997215 2.5805825403 93% => OK
Unique words: 158.0 145.348785872 109% => OK
Unique words percentage: 0.548611111111 0.540411800872 102% => OK
syllable_count: 423.9 419.366225166 101% => OK
avg_syllables_per_word: 1.5 1.55342163355 97% => OK
A sentence (or a clause, phrase) starts by:
Pronoun: 2.0 3.25607064018 61% => OK
Article: 9.0 8.23620309051 109% => OK
Subordination: 1.0 1.25165562914 80% => OK
Conjunction: 0.0 1.51434878587 0% => OK
Preposition: 0.0 2.5761589404 0% => More preposition wanted as sentence beginning.
Performance on sentences:
How many sentences: 11.0 13.0662251656 84% => Need more sentences. Double check the format of sentences, make sure there is a space between two sentences, or have enough periods. And also check the lengths of sentences, maybe they are too long.
Sentence length: 26.0 21.2450331126 122% => The Avg. Sentence Length is relatively long.
Sentence length SD: 50.7352551556 49.2860985944 103% => OK
Chars per sentence: 130.181818182 110.228320801 118% => OK
Words per sentence: 26.1818181818 21.698381199 121% => OK
Discourse Markers: 5.45454545455 7.06452816374 77% => OK
Paragraphs: 4.0 4.09492273731 98% => OK
Language errors: 0.0 4.19205298013 0% => OK
Sentences with positive sentiment : 2.0 4.33554083885 46% => More positive sentences wanted.
Sentences with negative sentiment : 3.0 4.45695364238 67% => 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: 0.248960389669 0.272083759551 92% => OK
Sentence topic coherence: 0.0887603773464 0.0996497079465 89% => OK
Sentence topic coherence SD: 0.11258516983 0.0662205650399 170% => OK
Paragraph topic coherence: 0.148532968374 0.162205337803 92% => OK
Paragraph topic coherence SD: 0.113077867734 0.0443174109184 255% => More connections among paragraphs wanted.
Essay readability:
automated_readability_index: 15.1 13.3589403974 113% => OK
flesch_reading_ease: 53.55 53.8541721854 99% => OK
smog_index: 3.1 5.55761589404 56% => Smog_index is low.
flesch_kincaid_grade: 12.3 11.0289183223 112% => OK
coleman_liau_index: 11.84 12.2367328918 97% => OK
dale_chall_readability_score: 8.6 8.42419426049 102% => OK
difficult_words: 67.0 63.6247240618 105% => OK
linsear_write_formula: 13.5 10.7273730684 126% => OK
gunning_fog: 12.4 10.498013245 118% => OK
text_standard: 12.0 11.2008830022 107% => OK
What are above readability scores?
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Rates: 65.0 out of 100
Scores by essay e-grader: 19.5 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.