This is true, but if that did happen presumably we could find some evidence for it, since it would be a relatively common occurrence during the period where ear

This is true, but if that did happen presumably we could find some evidence for it, since it would be a relatively common occurrence during the period where earth was capable of abiogenesis. Because if it occurred at least twice, it probably happened many more times. The counterpoint is that the fossil record is very incomplete when going that far back, seeing as tectonic subduction literally wipes the slate clean.