LOS ANGELES — Horton hears a hit.

Family audiences boosted 20th Century Fox's animated tale "Dr. Seuss' Horton Hears a Who!" to a $45.1 million debut, the best opening so far this year, according to studio estimates today.

Featuring the voices of Jim Carrey and Steve Carell in an adaptation of the beloved storybook about an elephant defending a microscopic community from destruction, "Horton Hears a Who" is the latest computer-animated film from Blue Sky Studios, the outfit behind the "Ice Age" flicks.

The previous weekend's No. 1 movie, the Warner Bros. action yarn "10,000 B.C.," slipped to second place with $16.4 million, raising its 10-day total to $61.2 million.

Summit Entertainment's "Never Back Down," about a troubled youth who finds purpose in the sport of mixed martial arts fighting, opened in third place with $8.6 million.

The weekend's other new wide release, Rogue Pictures' horror thriller "Doomsday," premiered at No. 7 with $4.7 million. The movie follows a team of specialists trying to find a cure for a ravaging epidemic that has forced the quarantine of Scotland.

"Horton Hears a Who" topped the $40.1 million opening in January for "Cloverfield," which previously was the year's No. 1 debut.

"It's a 'who-mongous' opening, and it's playing to all Whos two to 92," said 20th Century Fox distribution executive Chris Aronson. "If you can't do an ode to Dr. Seuss with an opening like this, come on."

The new movie was the fourth-best opening ever in March. With the two "Ice Age" movies, "Horton" and "Robots," Blue Sky Studios now has four of the top six March debuts of all time.

"They should rename March 'Blue Sky month,"' said Paul Dergarabedian, president of box-office tracker Media By Numbers.

"Horton" landed in between the debut weekends of two other big-screen Seuss adaptations, 2000's "How the Grinch Stole Christmas" with $55.1 million and 2003's "The Cat in the Hat" with $38.3 million.

With solid reviews for "Horton," Fox is counting on strong business through Easter next Sunday and beyond, as many students are out of school, Aronson said.

Hollywood's revenues rose for the first time after four straight weekends of declining business. Overall receipts came in at $127 million, up 8.5 percent from the same weekend last year, according to Media By Numbers.

Estimated ticket sales for Friday through Sunday at U.S. and Canadian theaters, according to Media By Numbers LLC. Final figures will be released Monday.

1. "Dr. Seuss' Horton Hears a Who!", $45.1 million.

2. "10,000 B.C.," $16.4 million.

3. "Never Back Down," $8.6 million.

4. "College Road Trip," $7.9 million.

5. "Vantage Point," $5.4 million.

6. "The Bank Job," $4.9 million.

7. "Doomsday," $4.7 million.

8. "Semi-Pro," $3 million.

9. "The Other Boleyn Girl," $2.9 million.

10. "The Spiderwick Chronicles," $2.4 million.