Bernard said "wiped off the face of the earth" meant killed, as in dead, extinct, kicked the bucket, gone to meet their maker...

Well, "Which mammal, which is not egg-laying (e.g. duck billed platypus), could theoretically be completely wiped off the face of the earth, yet, the following day thousands of young could be born?"

Theoretically, all of us mammals could be wiped off the face of the earth on any particular day, but thousands of us could be born the next day. Of course, I'd go out on a limb and say the first "could be" doesn't happen.

In other words, A could happen, OR B could happen. A and B both could not happen. I know, I know - try again.