This is Figure 2 from Round (1980). Frank Round considered concept of Protista. He argued that the earliest lines of eukaryotes were heterotrophic and became autotrophic by endosymbiosis. Then, he said that although some of the autotrophic lines lost their photosynthetic abilities, they could still be divided into Plants and Animals. Thus, he considered the concept of Protista as a failed idea that needed to be relegated to the history of Biology.