Cast member Joel Courtney gestures at the premiere of the movie "Super 8" at the Regency Village theatre in Los Angeles June 8, 2011. The movie opens in the U.S. on June 10.[Photo/Agencies]

To Hollywood's great surprise, moviegoers will show up en masse for the rare summer film that features real actors, an original story and some genuine thrills.

The new sci-fi mystery "Super 8" easily claimed the top spot at the weekend box office in North America after selling about $38 million worth of tickets, despite concerns about a marketing campaign that kept some key elements under wraps.

Its distributor, Paramount Pictures, said on Sunday the tally includes a $1 million contribution from a limited number of sneak-peak previews on Thursday, a day before the film opened in wide release across the United States and Canada.

Industry pundits had forecast a three-day opening in the $25 million to $30 million range, while some movie theater executives had worried it might struggle to hit $20 million.

In a summer of familiar sequels and superheroes, "Super 8" is the first original, live-action non-sequel to take the No. 1 slot in almost three months. The thriller "Limitless" led the field during the weekend of March 18-20.

Last weekend's champion, "X-Men: First Class," the fifth entry in the Marvel comic book series, slipped to No. 2 with $25.0 million. It was followed by "The Hangover, Part II" with $18.5 million in its third weekend. The "X-Men" sequel remained the top choice overseas with sales of $42.2 million.

The only other big new film in North America bombed. The kids movie "Judy Moody and the NOT Bummer Summer" opened at No. 7 with just $6.3 million, coming in at the low end of expectations in the $6 million to $10 million range.

MISSING ALIEN

The advance buzz for "Super 8" was hardly deafening, even with the A-list imprimatur of J.J. Abrams as writer/director and Steven Spielberg as a producer. Abrams convinced skeptical Paramount executives to run a campaign that retained a sense of old-fashioned mystery, earning scorn from industry pundits as surveys showed little enthusiasm among prospective moviegoers.

The plot centers on a group of kids in a small Ohio town who spend the summer of 1979 making a home movie using the 8mm film format that was popular back then and from which the film gets its title. They witness a train crash, which triggers a series of inexplicable events and disappearances. The trailer deliberately did not show the alien creature around which the film revolves.

As industry pundits began to second-guess that strategy, Paramount last week announced the film would open a day ahead of schedule on Thursday in a sneak-preview promotion with Twitter. A glimpse of the creature was also sent online.

The last-minute fix, along with overwhelmingly positive reviews, seemed to do the trick. The film cost a relatively modest $50 million to make, according to Paramount.

In an age where movie trailers routinely act like mini-synopses, Paramount walked "a fine line" between making the movie interesting, but not wanting to give away too much information, said Don Harris, executive vice-president of domestic distribution at the Viacom Inc unit.

With a hefty 71 percent of the audience aged over 25 -- despite a cast of youngsters -- Harris was confident the film would pull in younger viewers as the summer progresses.

"Super 8" also earned $6.7 million from nine foreign markets, led by $2.7 million in Australia where it trailed the "Hangover" and "X-Men" sequels.

Elsewhere, "Judy Moody" is the latest in a string of underperforming literary adaptations aimed at young girls, including last summer's Beverly Cleary adaptation "Ramona and Beezus" and a 2007 adaptation of the Nancy Drew books.

It was financed for nearly $20 million by Sarah Siegel-Magness and her husband Gary Magness, the couple who backed the Oscar-winning movie "Precious." Closely held studio Relativity Media distributed the movie for a fee.

"X-Men: First Class" has earned $99 million after two weekends, dropping a relatively slight 55 percent from its opening round. Its foreign total stands at $124 million from about 66 markets. It was distributed by 20th Century Fox, a unit of News Corp.

"The Hangover: Part II" raced to $217 million in North America and an additional $216 million in 55 markets. The sequel was distributed by Warner Bros. Pictures, a unit of Time Warner Inc.