Final answer:
Alfred Wegener pointed to the distribution of plants and animals as evidence for his theory of continental drift, which suggested that Earth's continents were once part of a supercontinent called Pangaea.
Step-by-step explanation:
In explaining that Earth's continents were in motion, not fixed in place, Alfred Wegener pointed to certain distributions of plants and animals. Wegener proposed the theory of continental drift based on evidence such as the congruence of continental shapes, fossil records showing similarities between fossils found in South America and Africa, and resemblances among living animal species on different continents. He theorized that these continents were once joined together in a supercontinent named Pangaea.
Initially, Wegener's idea was met with skepticism due to the lack of a mechanism to explain how continents could move. Over the decades, the advancement in geology, oceanography, and geophysics led to the acceptance of plate tectonics as the mechanism behind continental drift, validating Wegener's hypothesis.