The original family who had begun to build a palace to rival Nonesuch had died out before they had put up little more than the gateway, […].

Shepard: I thought you always needed another species to serve as one of the parents.
Liara: Think about it, Shepard. If we were not able to mate with our own species, we would have died out long before we ever mastered space flight and left our homeworld.

However, apart from all this, the Chief was a grand old man, belonging to a class of individualists which seems to be dying out in these days, when standard behaviour seems to be as prevalent as standard designs.

Die out

Meaning

Verb