Roland Emmerich's prehistoric saga didn't fare as well as his previous releases The Day After Tomorrow and Independence Day, although those titles launched during the summer.
Opening in second was the comedy College Road Trip on $14m, which stars Martin Lawrence as an over protective father who accompanies his daughter on an expedition to choose a university.
Overall box office tumbled 34% against the same weekend last year, no surprise given that 300 launched a year ago on $71m. This weekend's top 12 titles combined for $91.8m and it was the fourth consecutive drop.
Lionsgate's heist thriller The Bank Job with Jason Statham opened in fifth place on $5.7m.
New Line's champion from last weekend, Semi-Pro, fell three places on $5.9m from $24.8m after two weekends, while Sony's Vantage Point ranked third on $7.5m for $51.7m in its third weekend.
Period drama The Other Boleyn Girl, released domestically through Sony, fell three to seventh in its second weekend on $4m for $14.6m.
Focus Features' drama Miss Pettigrew Lives For A Day with Frances McDormand and Amy Adams launched in 11th place on $2.5m.
Next weekend's wide releases are: Fox's animated release Horton Hears A Who voiced by Jim Carrey and Steve Carell and Universal/Rogue's action title Doomsday starring Bob Hoskins and Rhonda Mitra.
Estimated Top 10 North America Mar 7-9, 2007
Film (Dist)/Int'l dist/Est wkd gross/Est total to date
1 (-) 10,000 BC (Warner Bros) WBPI $35.7m -
2 (-) College Road Trip (Buena Vista) WDSMPI $14m -
3 (2) Vantage Point (Sony) SPRI $7.5m $51.7m
4 (1) Semi-Pro (New Line) NLI $5.9m $24.8m
5 (-) The Bank Job (Lionsgate) Arclight Films $5.7m -
6 (3) The Spiderwick Chronicles (Paramount) PPI $4.8m $61.7m
7 (4) The Other Boleyn Girl (Sony) Focus Features International/UPI $4m $14.6m
8 (5) Jumper (Fox) Fox Int'l $3.8m $72.5m
9 (6) Step Up 2 The Streets (Buena Vista) Summit $3m $53m
10 (7) Fool's Gold (Warner Bros) WBPI $2.8m $62.8m