Evolution of Cetaceans - TOEFL iBT® Reading Practice Test Paper with Answer Key

The Reading section of the TOEFL iBT^® is an essential component of the exam and requires a strong grasp of the English language. Whether this is your first time taking the test or if you are aiming to boost your score, effective practice is vital. 

This practice test is designed specifically to help you improve your comprehension and reading skills while getting familiar with the format and question types found in the actual TOEFL exam. By participating in this practice test, you'll be better equipped to handle reading comprehension tasks, recognize important information, and enhance your overall performance. Start your TOEFL journey towards success with this Reading Practice Test on the topic- ‘Evolution of Cetaceans’!

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. 

Evolution of Cetaceans

It is obvious that cetaceans, including whales, porpoises, and dolphins, are mammals. They breathe air using lungs, not gills, and give birth to live offspring. Despite their streamlined bodies, lack of hind legs, and possession of a fluke and blowhole, which are characteristic of marine mammals, their connection to land-dwelling mammals is unmistakable. However, unlike sea otters and pinnipeds (such as seals, sea lions, and walruses) whose limbs function both on land and in water, envisioning the appearance of the first whales is challenging. Extinct fully marine cetaceans are documented in the fossil record, raising questions about how the transition from a terrestrial mammal to a marine whale occurred. Until recently, fossils representing transitional forms between land mammals and cetaceans were lacking.

Exciting recent findings have enabled researchers to piece together the probable beginnings of cetaceans. In 1979, during a fossil hunt in northern Pakistan, a team stumbled upon the oldest known whale fossil. This fossil, named Pakicetus in tribute to the nation of its discovery, was entombed in sedimentary rocks originating from river deposits dating back 52 million years. Remarkably, these deposits were in close proximity to the ancient Tethys Sea.

The complete Pakicetus fossil comprises a skull of an archaeocyte, an extinct precursor group to modern cetaceans. Despite being just a skull, this fossil yields valuable insights into cetacean origins. While resembling cetaceans, the skull lacks the enlarged space for receiving underwater sound found in modern whales, suggesting Pakicetus may have detected sound through its ear opening like land mammals. Additionally, it lacks a blowhole, a cetacean adaptation for diving. Nonetheless, other characteristics indicate Pakicetus as a transitional form between mesonychids, extinct flesh-eating mammals, and cetaceans. Experts propose that Pakicetus likely fed on fish in shallow waters and was not yet suited for open ocean life, probably reproducing on land.

In Egypt in 1989, another significant discovery occurred with the unearthing of several skeletons of an early whale, Basilosaurus, found in sediments deposited by the Tethys Sea and now visible in the Sahara desert. This species lived approximately 40 million years ago, emerging 12 million years after Pakicetus. Among the numerous incomplete skeletons discovered were some containing a complete hind leg, a feature previously unseen in archaeocetes, showcasing a foot with three small toes. However, these legs would have been too small to provide support for the 50-foot-long Basilosaurus on land. This confirms Basilosaurus as a fully marine whale with hind legs that were likely nonfunctional or vestigial.

A particularly thrilling discovery was documented in 1994, originating in Pakistan as well. The now-extinct Ambulocetus natans, known as "the walking whale that swam," inhabited the Tethys Sea approximately 49 million years ago. This timeframe places it roughly 3 million years after Pakicetus but 9 million years prior to Basilosaurus. The fossil fortuitously includes a significant portion of its hind legs, which were robust and terminated in lengthy feet resembling those of present-day pinnipeds. These legs functioned effectively both on land and in water. Despite lacking a fluke, the primary mode of propulsion for modern cetaceans, Ambulocetus utilized a swimming technique akin to contemporary whales by undulating the posterior part of its body vertically, utilizing its sizable hind legs for aquatic propulsion. On land, where it likely reproduced, Ambulocetus likely maneuvered similarly to a modern sea lion. This species served as a crucial link between terrestrial and marine life, showcasing the evolutionary transition from land to sea in cetaceans.

Directions

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

Paragraph 1

It is obvious that cetaceans, including whales, porpoises, and dolphins, are mammals. They breathe air using lungs, not gills, and give birth to live offspring. Despite their streamlined bodies, lack of hind legs, and possession of a fluke and blowhole, which are characteristic of marine mammals, their connection to land-dwelling mammals is unmistakable. However, unlike sea otters and pinnipeds (such as seals, sea lions, and walruses) whose limbs function both on land and in water, envisioning the appearance of the first whales is challenging. Extinct fully marine cetaceans are documented in the fossil record, raising questions about how the transition from a terrestrial mammal to a marine whale occurred. Until recently, fossils representing transitional forms between land mammals and cetaceans were lacking.

1. Which inference regarding early sea otters can be drawn from paragraph 1?
   1. Imagining their appearance is not a challenge.
   2. They existed in large populations.
   3. Their habitat was exclusively the sea.
   4. They left few fossilized traces.

Paragraph 3

The complete Pakicetus fossil comprises a skull of an archaeocyte, an extinct precursor group to modern cetaceans. Despite being just a skull, this fossil yields precious insights into cetacean origins. While resembling cetaceans, the skull lacks the enlarged space for receiving underwater sound found in modern whales, suggesting Pakicetus may have detected sound through its ear opening like land mammals. Additionally, it lacks a blowhole, a cetacean adaptation for diving. Nonetheless, other characteristics indicate Pakicetus as a transitional form between mesonychids, extinct flesh-eating mammals, and cetaceans. Experts propose that Pakicetus likely fed on fish in shallow waters and was not yet suited for open ocean life. It probably bred and gave birth on land.

1. The term "precious" as used in the passage is most similar in meaning to:
   1. A. exact
   2. B. scarce
   3. C. valuable
   4. D. initial

1. Pakicetus shares similarities with modern cetaceans in terms of
   1. A. Hearing mechanisms
   2. B. Diving adaptations
   3. C. Skull shapes
   4. D. Breeding sites

1. The term "It" in the passage refers to:
   1. A. Pakicetus
   2. B. Fish
   3. C. Life
   4. D. Ocean

Paragraph 4

In Egypt in 1989, another significant discovery occurred with the unearthing of several skeletons of an early whale, Basilosaurus, found in sediments deposited by the Tethys Sea and now exposed in the Sahara desert. This species lived approximately 40 million years ago, emerging 12 million years after Pakicetus. Among the numerous incomplete skeletons discovered were some containing a complete hind leg, a feature previously unseen in archaeocetes, showcasing a foot with three small toes. However, these legs would have been too small to provide support for the 50-foot-long Basilosaurus on land. This confirms Basilosaurus as a fully marine whale with hind legs that were likely nonfunctional or vestigial.

1. The term "exposed" in the passage is most similar in meaning to
   1. A. explained
   2. B. visible
   3. C. identified
   4. D. located

1. The discovery of Basilosaurus's hind leg was important because it indicated that Basilosaurus
   1. A. existed after the ambulocetus natans
   2. B. coexisted with Pakicetus
   3. C. possessed proficient swimming abilities
   4. D. lacked the capability to walk on land

Paragraph 5 

A particularly thrilling discovery was documented in 1994, originating in Pakistan as well. The now-extinct Ambulocetus natans, known as "the walking whale that swam," inhabited the Tethys Sea approximately 49 million years ago. This timeframe places it roughly 3 million years after Pakicetus but 9 million years prior to Basilosaurus. The fossil fortunately includes a significant portion of its hind legs, which were robust and terminated in lengthy feet resembling those of present-day pinnipeds. These legs functioned effectively both on land and in water. Despite lacking a fluke, the primary mode of propulsion for modern cetaceans, Ambulocetus utilized a swimming technique akin to contemporary whales by undulating the posterior part of its body vertically, utilizing its sizable hind legs for aquatic propulsion. On land, where it likely reproduced, Ambulocetus likely maneuvered similarly to a modern sea lion. This species served as a crucial link between terrestrial and marine life, showcasing the evolutionary transition from land to sea in cetaceans.

1. Why did the author choose to use the word "fortunately" when noting that the Ambulocetus natans fossil contained hind legs?
   1. A. It is uncommon to find fossilized legs of early whales.
   2. B. The legs offered significant insights into cetacean evolution.
   3. C. This finding enabled scientists to reconstruct whale skeletons.
   4. D. Prior to this discovery, only the front legs of early whales had been found.

1. Among the sentences provided, which one accurately conveys the crucial information contained in the highlighted sentence in the passage? Options that are incorrect either alter the meaning or omit essential details.
   1. A. Ambulocetus swam by moving its body up and down, despite lacking a backbone.
   2. B. The fact that Ambulocetus lacked a backbone did not hinder its swimming, which involved moving its body up and down.
   3. C. Ambulocetus's swimming style, characterized by vertical body movements, was achieved without a backbone.
   4. D. Ambulocetus swam by undulating its body vertically, despite the absence of a backbone.

Paragraphs 1 and 2

Extinct fully marine cetaceans are documented in the fossil record, (A) raising questions about how the transition from a terrestrial mammal to a marine whale occurred. (B) Until recently, fossils representing transitional forms between land mammals and cetaceans were lacking. (C) Exciting recent findings have enabled researchers to piece together the probable beginnings of cetaceans. (D) In 1979, during a fossil hunt in northern Pakistan, a team stumbled upon the oldest known whale fossil. 

1. Directions: Examine the section of the text shown above. The letters (A), (B), (C), and (D) signify potential insertion points for the following sentence.
   
   “This is a question that has puzzled scientists for ages.”
   
   Where would the sentence best fit?
   1. A. Choice A
   2. B. Choice B
   3. C. Choice C
   4. D. Choice D
2. Directions: Below is an introductory sentence for summarizing the passage. You need to choose three answer choices that represent the most significant ideas in the passage to complete the summary. Some answer choices are irrelevant or minor ideas not discussed in the passage. This question carries a weight of 2 points.
   
   This passage discusses fossils that help to explain the likely origins of cetaceans—whales, porpoises, and dolphins.
   
   
   •  
   •  
   •  
   
   
   Answer Choices
   1. Recent fossil discoveries have contributed to revealing the connection between terrestrial mammals and cetaceans.
   2. The identification of Ambulocetus natans offered proof of a whale species that inhabited both land and sea environments.
   3. The remains of Basilosaurus were uncovered in the former Tethys Sea, an area abundant in fossilized remains.
   4. Pakicetus holds the distinction of being the most ancient whale fossil discovered to date.
   5. Fossils believed to represent transitional stages between land-dwelling mammals and aquatic whales were uncovered.
   6. Ambulocetus utilized its hind limbs for propulsion while swimming in water.

Answer Key with Explanation for TOEFL Reading Passage - Evolution of Cetaceans

1. Answer: A

Explanation: This is an inference question seeking details inferred from the first paragraph. Option A is the accurate response as paragraph 1 specifies that sea otters differ from early mammals, whose appearances are challenging to envision. Therefore, it can be inferred that the early appearance of sea otters is straightforward or not challenging to imagine.

2. Answer: C

Explanation: This is a Vocabulary question. The term being tested is "precious," which is emphasized in the text. The accurate response is option C, which states "valuable." Anything described as precious holds significant importance and is consequently valuable.

3. Answer: C

Explanation: This is a factual Information question. The correct option is Choice C. In Paragraph 3, the text delineates the distinctions and resemblances between Pakicetus and contemporary cetaceans. Sentence 3 within that paragraph specifies their shared similarity in skull structure. Contrarily, the remaining choices highlight variances rather than commonalities.

4. Answer: A

Explanation: This is a Reference question. The term under being tested is "It," which is emphasized in the text. This represents a straightforward pronoun-reference question. Option A, "Pakicetus," is the accurate selection. In this context, "It" pertains to a creature that likely reproduced and delivered offspring on land, a description that solely fits Pakicetus among the given options.

5. Answer: B

Explanation: This is a Vocabulary question. The term under examination is "exposed," which is emphasized in the text. The accurate response is option B, "visible." "Exposed" signifies "uncovered," and a skeleton that is uncovered is capable of being seen. Similarly, "visible" denotes "capable of being seen."

6. Answer: D

Explanation: This is a factual Information question. Choice D is the correct option because it stands out as the sole detail specifically addressed regarding the skeleton of Basilosaurus in paragraph 4, signifying its importance. Although Choice A is accurate, it lacks the detailed discussion found in Choice D, thereby not capturing the significance of the discovery. Choice C remains unmentioned, and Choice B does not align with the facts presented.

7. Answer: B

Explanation: This is an Inference question asking for a conclusion that can be drawn from the passage. Paragraph 5 indicates that the discovery mentioned in the passage offered valuable insights to scientists that would have been difficult to acquire otherwise. From this, it can be inferred that the discovery was fortuitous or "lucky." The passage does not provide evidence for any other options, making choice B the appropriate answer.

8. Answer: C

Explanation: This is a Sentence Simplification question. As with all of these questions, a single sentence in the passage is highlighted:

Despite lacking a fluke, the primary mode of propulsion for modern cetaceans, Ambulocetus utilized a swimming technique akin to contemporary whales by undulating the posterior part of its body vertically, utilizing its sizable hind legs for aquatic propulsion.

The correct choice is C as it includes all the necessary details from the highlighted sentence. Option A is incorrect because Ambulocetus did possess a backbone. Option B is inaccurate because the sentence mentions that the backbone indicated how Ambulocetus swam, not that it lacked a fluke. Option D is incorrect because the sentence indicates that Ambulocetus and contemporary whales swam similarly.

9. Answer: B

Explanation: This is an Insert Text question. You can see the four possible answer

choices in paragraphs 1 and 2.

Extinct fully marine cetaceans are documented in the fossil record, (A) raising questions about how the transition from a terrestrial mammal to a marine whale occurred. (B) Until recently, fossils representing transitional forms between land mammals and cetaceans were lacking. (C) Exciting recent findings have enabled researchers to piece together the probable beginnings of cetaceans. (D) In 1979, during a fossil hunt in northern Pakistan, a team stumbled upon the oldest known whale fossil. 

The sentence "This is a question that has puzzled scientists for ages" should be inserted after Choice B. The sentence preceding Choice B is posed as a rhetorical question, and the inserted sentence directly answers it. None of the other sentences are questions, so the inserted sentence wouldn't logically follow any of them.

10 Answer: A, B, E

Explanation: This is a Prose Summary question. It is completed correctly below.

This passage discusses fossils that help to explain the likely origins of cetaceans—whales, porpoises, and dolphins.

Correct Choices

Choice A, which states that "Recent fossil discoveries have contributed to revealing the connection between terrestrial mammals and cetaceans" is accurate as it encapsulates the primary concept conveyed throughout the passage. The passage predominantly focuses on discussing key discoveries such as Pakicetus, Basilosaurus, and Ambulocetus, which serve as evidence supporting this connection.

Choice B, which states, "The identification of Ambulocetus natans offered proof of a whale species that inhabited both land and sea environments" is accurate as it represents one of the primary findings mentioned in the passage, supporting the central argument that land mammals and cetaceans share a relationship.

Choice E, which states "Fossils believed to represent transitional stages between land-dwelling mammals and aquatic whales were uncovered" is accurate because, similar to choice A, it highlights the primary theme of the passage outlined in paragraph 1: these fossils are "clearly intermediate, or transitional, between land mammals and cetaceans." The rest of the passage elaborates on these findings.

Incorrect Choices

Choice C states that Basilosaurus's skeleton was discovered in the former Tethys Sea, an area abundant in fossil evidence. While this statement is accurate, it is considered a minor detail and thus deemed incorrect.

Choice D affirms that Pakicetus is the earliest fossilized whale known. This statement is factual but is categorized as a minor detail, rendering it incorrect.

Choice F mentions that Ambulocetus employed its hind legs for propulsion while swimming. This statement is correct but is classified as a minor detail, leading to its inaccuracy.

Now that you’ve completed these Reading Practice Questions, get ready to tackle some more TOEFL tests to boost your confidence! Share with us how many answers you guessed correctly in the comments section below!

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