[Campbell Biology P.792] The current global distribution of marsupials, primarily found in t... | Practice Question

The current global distribution of marsupials, primarily found in the Australian region and the Americas, is best explained by which of the following?

  • A: The continuous land bridge connection between Australia and other northern continents throughout the Cenozoic era, facilitating their spread.
  • B: The breakup of the supercontinent Pangaea, causing South America and Australia to become island continents where marsupials diversified in isolation.
  • C: Their superior competitive ability, allowing them to outcompete eutherians across most global habitats.
  • D: Extensive human-mediated introductions of marsupials to new continents over the last few centuries.

Explanation

The text states: 'Marsupials existed worldwide during the Mesozoic era, but today they are found only in the Australian region and in the Americas Figure 34.40c . The biogeography of marsupials illustrates the interplay between biological and geologic evolution... After the breakup of the supercontinent Pangaea, South America and Australia became island continents, and their marsupials diversified in isolation from the eutherians that began an adaptive radiation on the northern continents.' This directly supports option B.