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.

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.