> One has to imagine that there were a substantial number of misfires along the way too.

> Wouldn’t surprise if for us to know about 50 at this point there were orders of magnitude more that we’ll never know of.

Indeed! The Wikipedia article mentions it. To be honest, it's a surprise that we know about 50 cases, given the fact that almost none of them had any hard tissue or structures (like bones or shells) that can survive as fossils. Given those odds, we are likely underestimating the cases by several orders of magnitude.