I wouldn't quibble over whether it was a merger or an aquisition.
IMO, AUMN took over ECU. Without AUMN, ECU was just a cashless shell with a huge ore body with no hope of ever reaching revenues and earnings. I know they called it a "merger of equals." ECU was "taken under". If they hadn't sold, their stock would still probably be in the 80 cent range and eventually someone would have taken them over for $1.50 or so.