"Dinosaur," an animated tale about extinct reptiles, knocked "Gladiator" out of the arena with a $38.6 million weekend opening, the best movie debut this year, according to studio estimates Sunday.

The big premiere primes filmgoers for Memorial Day weekend, the traditional start to the summer movie season. "Dinosaur's" reign at the box office should be extinct by Wednesday, when Tom Cruise's "Mission: Impossible 2" opens.

"Gladiator" slipped to No. 2 with $19.1 million, pushing its gross to $102.5 million in 17 days. The Roman epic became the second film released this year, after "Erin Brockovich," to top the $100 million mark.

The raunchy campus comedy "Road Trip," about a student on a cross-country trek to retrieve a sex video mistakenly mailed to his girlfriend, debuted at No. 3 with $15 million.

Woody Allen made a rare appearance in the top 10 with "Small Time Crooks," which opened at No. 7 with $3.8 million. The comedy's three-day take nearly equaled the $4.2 million total gross of Allen's last film, "Sweet and Lowdown," though that movie never played wider than 239 theaters, while "Small Time Crooks" opened in 865.

"Small Time Crooks" stars Allen and Tracey Ullman as a low-class couple who try to pull a bank heist but come into riches through unexpected means.

Buoyed by Disney's "Dinosaur," the weekend's top 12 films grossed $101.2 million, down just $1 million from the same weekend last year, when 1999's biggest movie, "Star Wars: Episode I — The Phantom Menace," opened.

"Dinosaur" beat the opening weekends for "Gladiator" and "Scream 3," which both took in about $35 million in their first three days.

"It's a nice prelude to Memorial Day," said Paul Dergarabedian, president of box-office tracker Exhibitor Relations. "The momentum generated by all this moviegoing just keeps building and creates more moviegoing."

Using computer-animated creatures set against real-world landscapes, "Dinosaur" tells the story of the twilight of the reptiles, who are on the run from devastation caused by a killer meteor. The voice cast includes D.B. Sweeney, Alfre Woodard, Julianna Margulies, Ossie Davis and Joan Plowright.

The movie had the third biggest three-day opening for an animated feature, after Disney's "Toy Story 2" with $57.4 million last November and "The Lion King" with $40.9 million in June 1994.

"Dinosaur" averaged a meteoric $11,851 per theater in 3,257 cinemas, compared with $6,281 in 3,041 theaters for "Gladiator" and $5,929 in 2,530 theaters for "Road Trip."

"I guess we all, from kids on up, have this love affair with dinosaurs," said Chuck Viane, Disney's head of distribution. "I'm sure glad we depicted it in such a unique way that people really want to come and see it."