How did seafloor spreading help prove continental drift was true?

Answer 1

Evidence for continental drift is now extensive. Similar plant and animal fossils are found around different continent shores, suggesting that they were once joined. The fossils of the freshwater crocodile, found both in Brazil and South Africa, are one example; another is the discovery of fossils of the aquatic reptile Lystrosaurus from rocks of the same age from locations in South America, Africa, and Antarctica. There is also living evidence --- the same animals being found on two continents. An example of this is a particular earthworm found in South America and South Africa.

The complementary arrangement of the facing sides of South America and Africa is obvious, but is a temporary coincidence. In millions of years, seafloor spreading, continental drift, and other forces of tectonophysics will further separate and rotate those two continents. It was this temporary feature which inspired Wegener to study what he defined as continental drift, although he did not live to see his hypothesis become generally accepted.

It's generally saying that fossils have been found on landmasses far away from each other but because of seafloor spreading the continents could have once been connected.