Final answer:
Rugose corals, also known as robust forms, went extinct during the end-Permian mass extinction event.
Step-by-step explanation:
Rugose corals, also known as robust forms, went extinct during the end-Permian mass extinction event. This extinction event was a major event in Earth's history and led to the extinction of many different groups of organisms. Figure 7.7 shows diversity curves that paleontologists use to track the number of different fossils present during different time intervals, and it helps us understand when certain groups first evolved, diversified, and went extinct.