Yeah, Chixsulub was ~65 MY ago. There was a strike in Bolivia about 10 KY ago, but that's too far away. Chesapeake was also ~50-60 MY, as was Manson.
Thing is, any cataclysm big enough would have left clear traces, since the timeframe is within 4 KY, probably, since it's unlikely that there would have been Olmec pyramids much before that.
Maybe survivors/refugees, Bye, Bye Beringia (8,000 Year-Old Site In Florida)