By Lisa Richwine and Christine Kearney

LOS ANGELES (Reuters) - The aging tough guys of "Expendables 2" strong-armed the box office competition with a chart-topping $28.8 million in U.S. and Canadian ticket sales over the weekend, according to studio estimates.

Last week's domestic winner, "The Bourne Legacy" starring Jeremy Renner, slipped to the No. 2 spot with $17 million. In third place, newcomer 3D stop-motion movie "ParaNorman," earned $14 million.

The Expendables" sequel that unites "Rocky" actor Sylvester Stallone, "Terminator" Arnold Schwarzenegger and other 1980s stars, brings together a group of spies for an easy mission that turns dangerous when they seek revenge for a murder.

The film follows the surprise success in 2010 of the original "Expendables," which opened with $34.8 million domestically and ultimately grossed $274 million worldwide.

In addition to 66-year-old Stallone and 65-year-old Schwarzenegger, the film stars Bruce Willis, Jean-Claude Van Damme, and Chuck Norris, plus younger stars such as "Hunger Games" actor Liam Hemsworth.

Lions Gate had predicted a debut in the low $30 million range, while other box office watchers saw a possible $40 million opening.

David Spitz, executive vice president and general sales manager at Lions Gate, said a large proportion of the audience were aged over 25, which gave strength to its longer term prospects.

"It always bodes well for box office playability when you have an older audience," he said.

Lions Gate paid about $30 million for rights to distribute the film in the United States, Canada and Britain.

In a bid for family audiences, "ParaNorman" landed in a surprising third place with the story of a boy named Norman who speaks to ghosts and ghouls and works to save his town from an impending zombie apocalypse. The movie was produced by Laika studio, the team behind the critically acclaimed 2009 fantasy animation film "Coraline."

Adult comedy "The Campaign" took the fourth spot, earning $13.4 million with a U.S. domestic total now of $51.7 million.

New drama "Sparkle," about three young sisters pursuing fame as singers in 1960s Motown, earned $12 million and the weekend's No. 5 spot. The movie stars "American Idol" winner Jordin Sparks and features the final movie appearance by the late Whitney Houston. Sony produced the movie for about $14 million.

"Dark Knight Rises," the final movie in a Batman trilogy starring Christian Bale, took in $11.1 million at North American (U.S. and Canadian) theaters over the weekend. The blockbuster has grossed over $409.9 million in the U.S. and Canada since its July 20 debut.

Another newcomer, "The Odd Life of Timothy Green" from Walt Disney Co earned $10.9 million opening at North American (U.S. and Canadian) theaters, hitting the No. 7 spot.

The movie tells the story of a couple who wishes for a baby and soon finds an unusual, mud-covered boy standing at their door. Jennifer Garner and Joel Edgerton star. Disney spent about $25 million to make the movie, and has made $15.2 million since its opening on Wednesday. The studio had projected five-day sales of about $15 million.

Focus Features, a unit of Comcast Corp's Universal Studios, released "ParaNorman." Sony Corp's TriStar Pictures released "Sparkle."

(Reporting By Lisa Richwine and Christine Kearney; editing by Christopher Wilson)