LOS ANGELES— Move over, Dumbo. Horton is now the big elephant in the room.

The computer-animated adaptation "Dr. Seuss’ Horton Hears a Who!" trampled its rivals at the North American box office on Sunday with weekend sales of $45.1 million, the biggest opening of the year.

The $85 million 20th Century Fox release, which boasts the voices of Jim Carrey and Steve Carell, exceeded industry expectations but fell short of the $55.1 million bow of Carrey’s previous turn in a Seuss movie, 2000’s "How the Grinch Stole Christmas."

It does rank as Carrey’s best start since May 2003, when "Bruce Almighty" set a new watermark for the Canadian actor with a $67.95 million opening. Overall, "Horton" stands at No. 4 on Carrey’s all-time list.

Carrey voices the title character, a rubbery elephant who stumbles upon a speck that happens to be a tiny planet, home to a city called Who-ville. Carell voices the excitable mayor. In a rare moment of synchronicity with moviegoers, critics were also enthusiastic about the film.

Fox, a unit of News Corp, said "Horton" ranks as the fifth-biggest G-rated opening ever; the top honor is held by 2003’s "Finding Nemo" with $70.2 million. The studio expected Easter school vacations to boost the film’s midweek performance.

Last weekend’s champion, "10,000 BC," slipped to No. 2 with $16.4 million for the three-day period; the 10-day haul for Warner Bros. Pictures’ prehistoric epic stands at $61.2 million. The critically maligned saga has also earned $73 million internationally. The Time Warner Inc unit said the film cost more than $100 million to make.

Opening at No. 3 was "Never Back Down," a mixed martial arts movie targeted at male youngsters. It earned $8.6 million. The $20 million film is the debut production of privately held Summit Entertainment LLC.

Rounding out the top five were the Walt Disney Co Martin Lawrence comedy "College Road Trip" at No. 4 with $7.9 million, and the Sony Corp political thriller "Vantage Point" at No. 5 with $5.4 million. Their respective totals rose to $24.3 million after two weeks, and $59.2 million after four weeks.