Read the following paragraph and answer the question. Give ONLY the answer, no other words or explanation.

For example:

Answer: <most likely answer, as short as possible>.

Paragraph: 
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.


Question: Species of organisms that have permanently died out can also be called what?
extinct
Extinct species.