The caveman comedy "The Croods" left an indelible mark on the wall, opening at No. 1 with an estimated $44.7 million.

The 3-D adventure from DreamWorks Animation and 20th Century Fox features a voice cast including Nicolas Cage, Emma Stone and Catherine Keener. They play a prehistoric family encountering danger and strange new creatures when they're forced to find a new cave.

Opening strongly in second place with $30.5 million was "Olympus Has Fallen," an action thriller in which North Korean terrorists take over the White House. Gerard Butler leads an all-star cast that includes Aaron Eckhart as the president, Morgan Freeman and Angela Bassett. The opening far exceeded distributor FilmDistrict's expectations, which were in the under-$20 million range.