The TOEFL iBT®Reading Section plays a vital role in the TOEFL iBT® exam, evaluating one's ability to comprehend and analyze written English material. This section presents a passage followed by a set of questions designed to assess various reading skills.

Engaging in practice tests can significantly enhance preparation for the TOEFL iBT® Reading Section. These tests replicate the format and difficulty level of the actual exam, enabling test-takers to become acquainted with the passage types and question formats they will encounter.

Interested in developing your strengths and areas for improvement in the TOEFL iBT® Reading Section? Take this practice test focusing on "The History of Dinosaurs" and observe your progress!

Reading Instructions

• You have 15 minutes to read the following passage and answer all 10 questions related to it.  
• Most questions are worth 1 point, but the last question is worth more. The directions indicate how many points you will receive for that specific question. 
• The specific section/paragraphs have been provided again with the question for ease of understanding and quick solution.
• Some questions include a word or phrase that is highlighted in the question as well as in the paragraph for quick reference. 

For quite some time, paleontologists have contended that the extinction of the dinosaurs resulted from shifts in climate, which were influenced by gradual changes in the positions of continents and seas due to plate tectonics. Throughout the Cretaceous period, a time when dinosaurs thrived, vast shallow seas intermittently covered significant portions of the continents. Evidence from various sources, including geochemical data preserved in seafloor sediments, suggests that the climate during the Late Cretaceous was more temperate compared to present-day conditions. Days were neither excessively hot nor nights overly cold, while summers were moderately warm and winters not excessively frigid. These shallow seas likely helped stabilize the nearby air temperature, maintaining it relatively constant.

Towards the conclusion of the Cretaceous period, geological evidence indicates a gradual withdrawal of these seaways from the continents, returning to the major ocean basins. The reason for this retreat remains unknown. During approximately 100,000 years, as the seas receded, global climates underwent significant fluctuations: days grew warmer, nights cooler; summers hotter, winters colder. It is plausible that dinosaurs were unable to adapt to these drastic temperature shifts, contributing to their extinction.

However, if this were true, one might wonder why cold-blooded animals, like reptiles, managed to endure both freezing winters and scorching summers. Given their reliance on external sources to regulate their body temperature, it seems puzzling that they would remain unaffected while dinosaurs struggled to adapt, especially if, as some scientists argue, dinosaurs were warm-blooded. Critics further highlight that throughout the Mesozoic era, the shallow seaways retreated from and advanced onto the continents numerous times, raising questions as to why dinosaurs survived previous climatic fluctuations but not this one. While the idea of a straightforward climatic change linked to sea levels initially seems plausible, it fails to comprehensively account for all the available evidence.

Discontent with traditional theories explaining dinosaur extinctions led to an unexpected observation, which in turn sparked a novel hypothesis. As one transitions from rock layers signaling the conclusion of the Cretaceous period to those marking the onset of the Cenozoic era, numerous plants and animals vanish suddenly from the fossil record. Referred to as the K-Pg boundary, there is frequently a slender layer of clay sandwiched between the final stratum of Cretaceous rock and the initial layer of Cenozoic rock. Scientists theorized that by gauging the duration required to accumulate each centimeter of this clay, they could approximate the duration of the extinctions. They believed they could estimate the deposition time of the clay by assessing the concentration of the element iridium (Ir) it contained.

Iridium (Ir) has been scarce on Earth's surface since the planet's early history. Due to its metallic nature, it was primarily absorbed into Earth's core during the planet's cooling and solidification process. Ir is notably abundant in certain meteorites, preserving the original chemical composition of the solar system. Even today, minuscule meteorites continuously bombard Earth, falling on both land and sea. Scientists can estimate the duration required to deposit the observed amount of Ir in the boundary clay by measuring the frequency of these meteorite impacts over a specific timeframe. These calculations suggest that approximately one million years would have been necessary. However, additional credible evidence contradicts the notion that the deposition of the boundary clay could have taken one million years. Therefore, the unusually elevated concentration of Ir calls for a distinct explanation.

Based on these findings, scientists proposed a theory suggesting that a solitary massive asteroid, approximately 10 to 15 kilometers in diameter, collided with Earth, leading to the formation of the boundary clay. According to their calculations, the impact generated a vast dust cloud that blocked sunlight for several months, impeding photosynthesis in plants. This phenomenon resulted in plummeting surface temperatures on continents to below-freezing, triggering severe instances of acid rain. Moreover, the impact significantly elevated global temperatures over the long term through the greenhouse effect. This disruption to the food chain and climate would have caused the extinction of dinosaurs and other organisms in less than fifty years.

Directions: Once you have read the passage, answer the following questions.

Paragraph 1

For quite some time, paleontologists have contended that the extinction of the dinosaurs resulted from shifts in climate, which were influenced by gradual changes in the positions of continents and seas due to plate tectonics. Throughout the Cretaceous period, a time when dinosaurs thrived, vast shallow seas intermittently covered significant portions of the continents. Evidence from various sources, including geochemical data preserved in seafloor sediments, suggests that the climate during the Late Cretaceous was more temperate compared to present-day conditions. Days were neither excessively hot nor nights overly cold, while summers were moderately warm and winters not excessively frigid. These shallow seas likely helped stabilize the nearby air temperature, maintaining it relatively constant.

1. According to the information provided in paragraph 1, which of the following statements accurately describes the Late Cretaceous climate?
   1. Summers experienced high temperatures, while winters were marked by extreme cold.
   2. Shallow seas on the continents induced frequent fluctuations in temperature.
   3. The climate closely resembled that of the present day.
   4. Seasonal variations in climate were not significant, with minimal changes occurring from one season to another.

Paragraph 3

However, if this were true, one might wonder why cold-blooded animals, like reptiles, managed to endure both freezing winters and scorching summers. Given their reliance on external sources to regulate their body temperature, it seems puzzling that they would remain unaffected while dinosaurs struggled to adapt, especially if, as some scientists argue, dinosaurs were warm-blooded. Critics further highlight that throughout the Mesozoic era, the shallow seaways retreated from and advanced onto the continents numerous times, raising questions as to why dinosaurs survived previous climatic fluctuations but not this one. While the idea of a straightforward climatic change linked to sea levels initially seems plausible, it fails to comprehensively account for all the available evidence.

1. Why does the author bring up the survival of cold-blooded animals, like reptiles in paragraph 3?
   1. To contend that dinosaurs might have perished due to not being cold-blooded animals.
   2. To cast doubt on the sufficiency of the hypothesis linking climatic change related to sea levels to the extinction of dinosaurs.
   3. To provide instances of animals capable of sustaining a viable body temperature more effortlessly than dinosaurs.
   4. To bolster a hypothesis suggesting that these animals were less affected by climate changes during the Cretaceous period than they are presently.

1. As per paragraph 3, which statement accurately describes the impact of climate changes preceding the Cretaceous period on dinosaurs?
   1. Climate fluctuations associated with the movement of seaways prior to the Cretaceous period did not lead to the extinction of dinosaurs.
   2. Climate alterations before the Cretaceous period caused significant variability in sea levels, resulting in the demise of dinosaurs.
   3. Frequent climate shifts before the Cretaceous period rendered dinosaurs more adept at regulating their body temperature.
   4. Prior to the Cretaceous period, there were minimal climate alterations, allowing dinosaurs to thrive.

1. The word “fluctuations" in the passage is closest in meaning to:
   1. extremes
   2. retreats
   3. period
   4. variations

Paragraph 4

Discontent with traditional theories explaining dinosaur extinctions led to an unexpected observation, which in turn sparked a novel hypothesis. As one transitions from rock layers signaling the conclusion of the Cretaceous period to those marking the onset of the Cenozoic era, numerous plants and animals vanish suddenly from the fossil record. Referred to as the K-Pg boundary, there is frequently a slender layer of clay sandwiched between the final stratum of Cretaceous rock and the initial layer of Cenozoic rock. Scientists theorized that by gauging the duration required to accumulate each centimeter of this clay, they could approximate the duration of the extinctions. They believed they could estimate the deposition time of the clay by assessing the concentration of the element iridium (Ir) it contained.

1. Which of the sentences below best conveys the essential information in the highlighted sentence in paragraph 4? Incorrect choices alter the meaning significantly or omit crucial details.
   1. The fossil record indicates a sudden extinction event affecting numerous plants and animals at the conclusion of the Mesozoic era.
   2. Limited fossils from the Mesozoic era have been preserved in the rock formations marking the conclusion of the Cretaceous period.
   3. Fossils dating from the Cretaceous period of the Mesozoic era up to the onset of the Cenozoic era have been displaced from their original rock layers.
   4. Organisms from the Mesozoic era were incapable of surviving into the Cenozoic era.

1. In paragraph 4, which of the following inquiries remains unanswered?
   1. What is the reason behind the presence of a layer of clay between the rocks of the Cretaceous and Cenozoic?
   2. What sparked scientists' interest in ascertaining the duration required for the deposition of the clay layer at the conclusion of the Cretaceous?
   3. What were the consequences of the unexpected observation made by scientists?
   4. Why did scientists seek additional information regarding the dinosaur extinctions occurring at the end of the Cretaceous?

Paragraph 5

Iridium (Ir) has been scarce on Earth's surface since the planet's early history. Due to its metallic nature, it was primarily absorbed into Earth's core during the planet's cooling and solidification process. Ir is notably abundant in certain meteorites, preserving the original chemical composition of the solar system. Even today, minuscule meteorites continuously bombard Earth, falling on both land and sea. Scientists can estimate the duration required to deposit the observed amount of Ir in the boundary clay by measuring the frequency of these meteorite impacts over a specific timeframe. These calculations suggest that approximately one million years would have been necessary. However, additional credible evidence contradicts the notion that the deposition of the boundary clay could have taken one million years. Therefore, the unusually elevated concentration of Ir calls for a distinct explanation.

1. Paragraph 5 suggests that a unique explanation for the presence of Ir in the boundary clay is necessary due to:
   1. The likelihood that the Ir in microscopic meteorites reaching Earth during the Cretaceous period would have been absorbed into Earth’s core.
   2. The inference that the Ir in the boundary clay was deposited over a million years ago.
   3. The observation that the concentration of Ir in the boundary clay exceeds that found in microscopic meteorites.
   4. The indication that the quantity of Ir in the boundary clay is too substantial to originate solely from microscopic meteorites during the period of clay deposition.

1. The term "notion" in the passage is most similar in meaning to which of the following?
   1. concept
   2. misconception
   3. falsehood
   4. fallacy

Paragraphs 5

Iridium (Ir) has been scarce on Earth's surface since the planet's early history. Due to its metallic nature, it was primarily absorbed into Earth's core during the planet's cooling and solidification process. Ir is notably abundant in certain meteorites, preserving the original chemical composition of the solar system. Even today, minuscule meteorites continuously bombard Earth, falling on both land and sea. Scientists can estimate the duration required to deposit the observed amount of Ir in the boundary clay by measuring the frequency of these meteorite impacts over a specific timeframe. (A) These calculations suggest that approximately one million years would have been necessary. (B) However, additional credible evidence contradicts the notion that the deposition of the boundary clay could have taken one million years. (C) Therefore, the unusually elevated concentration of Ir calls for a distinct explanation. (D)

1. Directions: Review the excerpt from the passage provided above. The letters (A), (B), (C), and (D) denote where the subsequent sentence could be incorporated.
   
   As a result, the notion that the Ir found in the boundary clay originated from microscopic meteorites cannot be endorsed.
   
   Where would the above sentence most appropriately belong?
   1. Choice A
   2. Choice B
   3. Choice C
   4. Choice D

1. Directions: You will find an introductory sentence for a summary of the passage provided below. Your task is to complete the summary by selecting the THREE answer choices that best represent the key ideas in the passage. Be mindful that some sentences may not align with the main ideas or may have minor points. This question carries a weight of 2 points.
   
   Scientists have long debated the connection between the extinction of dinosaurs and climate change.
   
   

   Answer Choices

   1. Preceding the retreat of the seas back into the major ocean basins were significant fluctuations in daily and seasonal climates.
   2. Certain crucial data pertaining to the extinction of dinosaurs at the conclusion of the Cretaceous period cannot be adequately explained by a simplistic climate change theory.
   3. The complete explanation for the retreat of seaways at the conclusion of the Cretaceous period remains elusive.
   4. The suddenness of extinctions occurring at the end of the Cretaceous period, coupled with the elevated concentration of iridium found in clay deposited during that era, has spurred the formulation of a novel hypothesis.
   5. Some scientists propose that the extinction of dinosaurs was the outcome of an asteroid colliding with Earth.
   6. Scientists utilize boundary clay layers, like the one marking the transition between the Mesozoic and Cenozoic eras, to ascertain the rate of decline of extinct species.

Before moving forward to check your answers, don't forget to go through the updated TOEFL Exam Pattern and Syllabus. 

Answer Key with Explanation for TOEFL iBT® Reading Passage - The History of Dinosaurs

1. Answer: D

Explanation: This is an Inference question assessing specific details from paragraph 1. The accurate response is option D. Paragraph 1 describes the Late Cretaceous climate as being milder than today's climate, with days not being excessively hot nor nights too cold, and summers not being too warm nor winters too frigid. Additionally, it mentions that shallow seas on the continents likely buffered the temperature of the nearby air, keeping it relatively constant. This implies that the climate did not undergo significant seasonal variations, aligning with option D.

2. Answer: B

Explanation: This is a Factual Information question aimed at specific details in paragraph 3. The correct answer is option B. In paragraph 3, the author mentions the survival of cold-blooded animals, like reptiles, to question the adequacy of the hypothesis that climatic changes associated with sea levels caused the extinction of dinosaurs. The author implies that if cold-blooded animals could survive extreme temperature changes, it raises doubts about whether climate change alone could have caused the extinction of dinosaurs. Therefore, option B best reflects the purpose of bringing up the survival of cold-blooded animals in the paragraph.

3. Answer: A

Explanation: This is an Inference question aimed at paragraph 3. The correct answer is option A. Paragraph 3 suggests that the climate changes preceding the Cretaceous period, including fluctuations in sea levels, did not result in the extinction of dinosaurs. This is in line with option A, which accurately describes the impact of climate changes before the Cretaceous period on dinosaurs as not leading to their extinction. Therefore, option A is the correct choice.

4. Answer: D

Explanation: This is a Vocabulary question assessing the highlighted word “fluctuations”. The correct answer is option D. The word "fluctuations" refers to changes or variations in something, indicating a level of instability or inconsistency. In the context of the passage, it refers to changes in sea levels or other climatic conditions. Option D, "variations," best captures the meaning of "fluctuations" in this context, making it the correct choice.

5. Answer: A

Explanation: This is a Rhetorical Purpose question aimed at specific details from paragraph 4. The correct answer is choice A. The highlighted sentence in paragraph 4 suggests that the fossil record indicates a sudden extinction event affecting many plants and animals at the end of the Mesozoic era. Option A accurately conveys this essential information by emphasizing the suddenness of the extinction event and its impact on various organisms. Options B, C, and D either provide unrelated information or alter the meaning of the original sentence, making them incorrect choices.

6. Answer: A

Explanation: This is a Rhetorical Purpose question aimed at understanding why the author mentions a specific detail in the passage. The correct answer is choice A. Paragraph 4 discusses various aspects related to the boundary clay layer, but it does not explicitly address the reason behind its presence between the rocks of the Cretaceous and Cenozoic eras. Therefore, option A accurately identifies an unanswered question from paragraph 4. Options B, C, and D do not pertain to the information provided in paragraph 4, making them incorrect choices.

7. Answer: D

Explanation: This is an Inference question. The correct answer is D. Paragraph 5 discusses the presence of iridium (Ir) in the boundary clay and suggests that a unique explanation is necessary due to the indication that the quantity of Ir in the boundary clay is too substantial to have solely originated from microscopic meteorites during the period of clay deposition. This suggests that additional factors or mechanisms must be considered to explain the high concentration of Ir in the boundary clay. Option D accurately reflects this reasoning, making it the correct choice. Options A, B, and C do not accurately capture the reason for the need for a unique explanation, making them incorrect choices.

8. Answer: A

Explanation: This is a Vocabulary question pertaining to the word “notion”. The correct answer is choice A. The term "notion" in the passage refers to an idea or concept. It represents a general understanding or belief about something. Option A, "concept," is the most similar in meaning to "notion" because it also refers to an idea or concept. Options B, C, and D, "misconception," "falsehood," and "fallacy," respectively, do not accurately capture the meaning of "notion" as it is used in the passage. They convey ideas of misunderstanding, untruthfulness, or erroneous beliefs, which are not synonymous with the neutral sense of "notion" in this context. Therefore, option A is the correct choice.

9. Answer: C

Explanation: This is an Insert Text question where you are required to select the appropriate place to insert the provided sentence within the passage. Among the four possible answer choices provided in paragraph 5, the sentence "As a result, the notion that the Ir found in the boundary clay originated from microscopic meteorites cannot be endorsed," is most fittingly inserted in choice (C).

The given sentence serves as a conclusion or follow-up statement based on the information provided in the preceding text. It explains the implications of the information presented and asserts a particular viewpoint.

In the context of the passage, this sentence would most appropriately follow the discussion about the high concentration of iridium (Ir) in the boundary clay and the need for a unique explanation. This discussion occurs in paragraph 5, where the passage explores the reasons why the presence of Ir in the boundary clay requires a special explanation. The sentence serves to emphasize the rejection of the notion that Ir originated solely from microscopic meteorites.

Therefore, the most suitable placement for this sentence would be after the paragraph discussing the need for a unique explanation, which corresponds to Choice C. Placing it here ensures that it directly follows the relevant discussion and effectively concludes that particular line of reasoning.

10. Answer: B, D, E

Explanation: This is a Prose Summary question, and the correct responses are B, D, and E. Therefore, options A, C, and F are incorrect.

Choice B: Choice B, “Certain crucial data pertaining to the extinction of dinosaurs at the conclusion of the Cretaceous period cannot be adequately explained by a simplistic climate change theory,” encapsulates a key idea in the passage, emphasizing the limitations of attributing dinosaur extinction solely to climate change. It highlights the need for a more nuanced understanding beyond a simplistic climate change theory.

Choice D: Choice D, “The suddenness of extinctions occurring at the end of the Cretaceous period, coupled with the elevated concentration of iridium found in clay deposited during that era, has spurred the formulation of a novel hypothesis,” highlights another significant aspect discussed in the passage - the suddenness of dinosaur extinctions and the presence of elevated iridium levels in clay, leading to the development of a new hypothesis. It underscores the importance of these factors in shaping scientific inquiry into the extinction event.

Choice E: Choice E, “Some scientists propose that the extinction of dinosaurs was the outcome of an asteroid colliding with Earth,” introduces the hypothesis proposed by some scientists that an asteroid impact caused the extinction of dinosaurs. It represents a pivotal idea in the passage, presenting an alternative explanation to climate change for the demise of dinosaurs.

Choice A: Choice A, “Preceding the retreat of the seas back into the major ocean basins were significant fluctuations in daily and seasonal climates,” is incorrect as it discusses fluctuations in climates preceding the retreat of seas, which, while relevant, does not directly address the main focus of the passage, which is the debate surrounding the extinction of dinosaurs.

Choice C: Choice C, “The complete explanation for the retreat of seaways at the conclusion of the Cretaceous period remains elusive,” is incorrect because it mentions the elusive explanation for the retreat of seaways, which, although mentioned in the passage, is not one of the central ideas discussed in relation to the extinction of dinosaurs.

Choice F: Choice F, “Scientists utilize boundary clay layers, like the one marking the transition between the Mesozoic and Cenozoic eras, to ascertain the rate of decline of extinct species,” is incorrect because it discusses the utilization of boundary clay layers, which, while mentioned in the passage, is not a key idea regarding the debate on dinosaur extinction and its potential causes.

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