The exact moment ground-laying eggers evolved is uncertain because the things that define them - reproductive organs - don't exactly fossilize well
I thought penises other than human had a bone in them.
Then again, I am not exactly sure what kind of creature I'm supposed to be imagining here.
Actually most animals don't have a bony penis, although I was mostly thinking of female internal organs =P You should ask trumpman on this, he's the expert after all