challenge: What was the significance of the discovery of bivalve fossils in the Virgin Limestone Member of the Moenkopi Formation in 2013?
  
  A. It cast doubt on previous claims that bivalve fauna only recovered in the Middle Triassic
  B. It revealed that all bivalve species were wiped out by the end-Permian mass extinction
  C. It suggested that bivalves only recovered in the Late Triassic
  D. It confirmed that bivalves went extinct at the end of the Permian period
  Answer: 