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 Sunday.

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.

“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.”

Estimated ticket sales for Friday through Sunday at U.S. and Canadian theaters, according to Media By Numbers LLC:

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.