All of the continents were once joined in a super-continent, known as Pangaea.

The distribution of fossils in Figure 1 suggests that these continents were once joined as shown, and furthermore, that the ring is evidence of a climatological isotherm (i.e., that Antarctica was at the South Pole, then as now, and that the animals thrived in a similar climate at the same latitute across all of the continents).

 

 

Figure 1. The distribution of Glossopteris fossils across 1) South America, 2) Africa, 3) Madagascar, 4) India, 5) Antarctica, and 6) Australia, courtesy Petter Bøckman.