The author hypothesizes that about 3 million years ago, the Antarctic ice sheet must temporarily have melted. This is based on the fact that we recently discovered 3-million-year-old fossils under the ice sheet of Antarctica. These fossils are of a kind that have only been found in ocean-floor sediments. In addition, severe climatic warming or volcanic activity in Antarctica’s mountains could have melted the ice sheet, which would have produced liquid water that submerged the area.

The author assumes there’s no way for the fossils to be found under the ice sheet unless the ice sheet was melted. This overlooks other explanations for the presence of the fossils. Perhaps, for example, the floor has shifted underneath the ice sheet, which allowed the fossils to move underneath when they were originally not underneath the ice sheet.