A polyaxial bone screw assembly includes a threaded shank body having an integral shank head receivable in a one-piece receiver having an upper channel for receiving a longitudinal connecting member and a lower cavity cooperating with a lower opening. A compression insert (some with an independent tool lock, lock and release feature and/or friction fit feature) and a split retaining ring articulatable with respect to both the shank head and the receiver (prior to locking) cooperate with the receiver to provide for pop- or snap-on assembly of the shank with the receiver either prior to or after implantation of the shank into a vertebra.
