For Over A Century, Scientists Have Believed That Dinosaurs And Birds Gmat Reading Comprehension

Reading Passage Question

For over a century, scientists have believed that dinosaurs and birds are closely related, but more recent evidence suggests that even some non-avian dinosaurs had feathers. Not long after Charles Darwin published The Origin of Species in 1859, Thomas Henry Huxley, a biologist and defender of Darwin's evolutionary theory, pointed out several similarities between dinosaurs and birds. He recognized similarities in their bone structures and drew upon his knowledge of skeletal likenesses between Archaeopteryx fossils and modern birds.

It wasn’t until the last twenty years, however, that scientists found evidence to support over a century of hypothesizing about the relationship between dinosaurs and birds. In the 1990s, several fossils of feathered dinosaurs were found in a sedimentary deposit in Liaoning, China. The deposit was particularly rich in well-preserved fossils, as the area had been buried in volcanic ash by eruptions in Mongolia during the early Cretaceous period. From these fossils, scientists have identified at least 17 non-avian dinosaurs that were feathered. In addition to finding feather impressions in fossils, scientists have also drawn conclusions about the relationship between dinosaurs and birds based on skeletal evidence such as the presence of quill knobs, the places where the wing feathers of modern birds attach to the bone. Furthermore, chemical evidence in some species suggests the presence of beta keratin, the primary protein present in bird feathers. Actual fossil feather impressions are rare, but these have allowed scientists to positively identify some of the known feathered dinosaurs. Scientists have also been able to infer the presence of feathers in others through a process called phylogenetic bracketing. Phylogenetic bracketing allows scientists to make inferences about the likelihood of an unknown trait based on what they know about closely related species. Current evidence, such as that found in fossils or identified through chemical analysis, has led that most modern birds contain beta keratin in their feathers as did the dinosaurs.

“For over a century, scientists have believed that dinosaurs and birds”- is a GMAT reading comprehension passage with a series of answers. The candidates must have a complete understanding and knowledge of the English GMAT reading comprehension. The comprehension consists of two questions in the entire section of GMAT Reading Comprehension. These questions are devised to detect candidates’ proficiency in comprehending concepts or knowledge. The candidates can boost their concepts by taking preparation from these GMAT Reading Comprehension Practice Questions.

Solutions and Explanation

  1. According to the passage, chemical evidence has led to which of the following conclusions?
  1. non-avian dinosaurs were more numerous than scientists previously thought
  2. phylogenetic bracketing is an accurate way to infer unknown traits
  3. dinosaurs and birds have a similar skeletal structure
  4. dinosaur features contained beta keratin, a protein also found in bird feathers
  5. the bones of some dinosaurs had quill knobs

Answer: (D)
Explanation:
From the given passage, it has been analyzed that modern birds and dinosaurs have beta keratin protein in common mostly in their feathers. Therefore, the fourth option satisfies the conclusion of the passage and thus it is correct. The remaining options of the passage go out of scope.

  1. The author of the passage is primarily concerned with:
  1. arguing that new evidence discredits previous e knowledge about the skeletal structure of dinosaurs
  2. explaining how phytogenic bracketing allows scientists to infer unknown traits
  3. offering evidence to support the idea that chemical evidence is essential in studying extinct species
  4. explaining the significance of feather impressions found in the fossils at Liaoning
  5. discussing recent evidence supporting the idea that some non-avian dinosaurs had feathers

Answer: (E)
Explanation:
The author of the passage mainly deals with the idea that certain non-avian dinosaurs possess feathers. The fifth option is concerned with the concept of the author and therefore it fulfills the discussion of the passage. The remaining options thereby go wrong as per the context of the passage.

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