[xcamel]

What ecosystem in the world hasn't lost a particular member, and has not had it replaced by the next nearest species on the food chain?

Hint: Saber toothed cats have gone extinct 5 times, and have reappeared 5 times. This is just how it is with nature.

[Dutch Boy]

Many followers of evolution refuse to accept it in practice. Things like this are natural.

[cajun-jack]

the ivory billed woodpecker had been extinct for many years, till one was found in arkansas a little while ago.