Arment's paper on the marsupial fossil record and the post-Flood boundary contains a major statistical error, which impacts the ability to quantitatively consider the implications of the fossil data in context of the various Flood boundary proposals he considers. Specifically, he considers arrivals of each boundary crossing taxon to be statistically independent. This assumption alone is responsible for the eyebrow-raising magnitude of the final probabilities (for all boundary positions). The Law of Total Probability should have been used to produce much more realistic probability estimates. An updated estimate of the probabilities for Australian marsupials is equivalent to calling 22 coin flips, rather than Arment's 68 dice rolls.