> a simultaneous species jump and mutation to create the FCS (since those are both roughly instantaneous by comparison). I don't know why you think this is nec

> a simultaneous species jump and mutation to create the FCS (since those are both roughly instantaneous by comparison). I don't know why you think this is necessary. The FCS shouldn't preclude the infection continuing in the original species, like I said it probably doesn't infectivity in bats and is neutral. And if the intermediate animal was infected with a common coronavirus for the species, all it takes is coinfection from a bat with the precursor to SARS-CoV-2 and a recombination event to create the FCS. Animals and humans across china are almost certainly getting infected with novel sarbecoviruses from bats every day. Most of them don't go anywhere. This one got "lucky" and stole some genetic material which made it better in the new host organism and now it is off to the races. Which is unlikely, but, again, pandemics are unlikely.