Marvel Studios’ Iron Man 2 kicked off the summer season as it powered to the fifth biggest domestic launch in history thanks to an estimated $133.6m opening weekend through Paramount.

Roughly $10.2m of this 2D-only release came from IMAX, setting a new mark for the company.

The release dominated the competition with ease and ranks only behind The Dark Knight’s $158.4m, Spider-Man 3’s $151.1m, The Twilight Saga: New Moon’s $142.8m, and the $135.6m opening weekend of Pirates Of The Caribbean: Dead Man’s Chest.

Robert Downey Jr, Mickey Rourke, Gwyneth Paltrow, Don Cheadle and Scarlett Johansson and Sam Rockwell star. Jon Favreau directed. Marvel Studios is owned by The Walt Disney Company.

Warner Bros’ A Nightmare On Elm Street fell one place to second on $9.2m for $43.5m after two weekends, and DreamWorks Animation-Paramount’s How To Train Your Dragonin third crossed $200m in its seventh weekend as $6.8m raised the tally to $201.1m.

Focus Features launched the documentary Babies in tenth place on $1.6m. The film charts the first year in the life of  four babies from different parts of the world.

Next weekend’s wide releases are: Universal’s Robin Hood from Ridley Scott starring Russell Crowe, Cate Blanchett and mark Strong; Summit Entertainment’s romance Letters To Julietstarring Amanda Seyfried; and Fox Searchlight’s romantic comedy Just Wright starring Queen Latifah and Common.

Estimated Top 10 North America May 7-9 2010

Film (Dist) / Est wkd gross / Est total to date

1 (-) Iron Man 2 (Marvel/Paramount) PPI $133.6m –

2 (1) A Nightmare On Elm Street (Warner Bros) $9.2m $48.5m

3 (2) How To Train Your Dragon (DreamWorks Animation/Paramount) PPI $6.8m $201.1m

4 (3) Date Night (Fox) Fox Int’l $5.3m $80.9m

5 (4) The Back-Up Plan (CBS Films) SPRI $4.3m $29.4m

6 (5) Furry Vengeance (Summit Entertainment) Summit Int’l $4m $11.6m

7 (7) Clash Of The Titans (Warner Bros) WBPI

$2.3m $157.8m

8 (9) Death At A Funeral (Screen Gems) SPRI $2.1m $38.3m

9 (6) The Losers (Warner Bros) WBPI $1.8m $21.5m

10 (-) Babies (Focus Features) StudioCanal $1.6m –