Genetic studies have led researchers to suggest that turtles are most closely related to the group that includes modern crocodiles. But studies of fossils have suggested instead that turtles are most closely related to other groups, such as the one that contains modern snakes. However, many of the fossil studies have relied on incomplete data sets. For a 2022 investigation, biologist Tiago R. Simões and colleagues examined more than 1,000 reptile fossils collected worldwide. From this large data set, they found clear agreement with the results of the genetic studies.
Which choice best describes the function of the underlined sentence?
Explanation
Context: The text sets genetic evidence linking turtles to crocodiles against fossil evidence linking them to other groups such as snakes, and the underlined sentence intervenes just before a 2022 study is introduced.
Answer: B) It describes a limitation of some studies about the origin of turtles.
Why? The sentence states that many of the fossil studies relied on incomplete data sets, identifying a weakness in the conclusions drawn from them. That shortcoming is what makes the Simões team's sample of more than 1,000 reptile fossils significant and explains why its agreement with the genetic results carries weight.
Traps:
- A) overview of fossil-examination tools → no instrument or technique is named, only the incompleteness of the data.
- C) summarizes research on crocodile evolution → crocodiles appear solely as a reference point for turtle relatedness.
- D) criticizes a belief about genetic studies → the criticism lands on the fossil studies, and the genetic findings end up supported.