Thanks for the replies .
To answer the questions :
Ticket purchased through AA.com.
All 4 original scheduled segments on BA .
Return portion of Ticket was in actual F class , I believe . Will verify later.
DXB flight was 4hours delayed by having to return to DXB after takeoff . Misconnect was therefore BA's responsibility.
EU 261 advice is excellent - I have 3 seats on this PNR, so that's big $$$ if I get even close to what is quoted.
Flight is about to take off - keep providing info and I'll check back after arrival in DFW.
Thsnks again.