What does presence of mesosaurus fossils tell about the initial location and positioning of south america africa antarctica

The answer is that these continents were once joined together in one big continent.

All continents were once connected as one supercontinent Pangea. On that supercontinent, many species lived across all the supercontinent, such as mesosaurus. But after continents spread apart, some populations remained on the different parts of the supercontinent. So, some population ended up on South Aamerica, some on Africa, and some on Antartica. The geological theory that explains how continents move through Earth's surface is called continental drift.

clumped distribution, because you'de have all of the population gathered in a relatively small are.

it's the most common because it provides protection and a mate for reproduction

example: humans, seeweed, cattles, etc.