Given the task definition and input, reply with output. Given a scientific passage and an answer, generate a question for the given answer.

Passage: Most of the organisms that once lived on Earth are now extinct. Earth's environment has changed many times. Many organisms could not adapt to the changes. They died out. The organisms that did survive passed traits on to their offspring. The changes added up, eventually producing the species we see today. Answer: extinct
Species of organisms that have permanently died out can also be called what?