PARK CITY, Utah – Who could have guessed, just two months ago, that “Michael Clayton” — a legal thriller derided by some critics as little more than a vanity project for star George Clooney — would surge past the likes of the period romance “Atonement,” the lauded musical “Sweeney Todd,” and the Sean Penn-directed epic “Into the Wild” to become one of this year’s leading contenders for Best Picture at the upcoming the Academy Awards?

And who could possibly have guessed, only a few weeks ago, that out of all this year’s best picture nominees, announced early Tuesday morning, that “Juno,” the sarcastic comedy about a teenage girl who spends the film’s opening portion of the story debating the merits of abortion, would rank as the most popular of all nominated films, raking in an estimated $87 million at the box office?

Few expected that the two films, Jason Reitman’s “Juno” and Tony Gilroy’s “Michael Clayton,” would have enough momentum to squeak their way onto this year’s Best Picture list. But as the nominees for the 80th annual Academy Awards were read Tuesday by Oscar winner Kathy Bates, the duo seemed like a natural fit to stand alongside the leading contenders –— the Coen brothers’ “No Country for Old Men” and Paul Thomas Anderson’s “There Will Be Blood.” Both films led the day with eight nominations apiece.

Rounding out this year’s Best Picture list is “Atonement,” the sweeping British adaptation of Ian McEwan’s wartime novel. While a winner at the Golden Globes, the film was snubbed by the Academy in the important Best Director category, meaning it will not sprint so much as limp into this, the final lap of the 2007 awards race. (The live Oscar telecast is scheduled for February 24, and the Academy of Motion Picture Arts and Sciences insists it will go forward regardless of the state of the ongoing writers’ strike.)

Tuesday’s announcements mark the beginning of the end for a most turbulent awards season, narrowing a field of a dozen Best Picture contenders that all seemed to have a legitimate chance at making the cut. Not far behind the Best Picture nominees were Tim Burton’s “Sweeney Todd: The Demon Barber of Fleet Street,” which won a Golden Globe for Best Picture, “The Diving Bell and the Butterfly,” which did secure a Best Director nod for Julian Schnabel, and “Into the Wild,” which even Monday was considered a serious contender by a number of critics out here at the Sundance Film Festival.

Watching the Best Picture nominations from within the bubble of Sundance, it was hard not to notice an indie-minded lining in the announcement –— a subtle changing of the guard, as proven names such as Denzel Washington (“The Great Debaters”) and Mike Nichols (“Charlie Wilson’s War”) were omitted in favor of fringe favorites and relative newcomers. The Coens have spent the better part of their careers on the outskirts of the movie industry. Mr. Anderson (“There Will Be Blood”) has established himself as one of the visionary filmmakers of his generation. Joe Wright (“Atonement”) has earned two Best Picture nominations with his first two films, but remains relatively anonymous in popular circles. And Jason Reitman (“Juno”), with a most unconventional film, has joined the industry’s elite with only his second directorial outing.

It is Mr. Gilroy, though, who stands out on this year’s Oscar roster. Once known for his writing (the “Bourne Identity” trilogy, “The Devil’s Advocate,” “Dolores Claiborne,” and others), his directorial debut earned him nods for directing and writing, and his film was nominated for Best Picture, Best Actor (Mr. Clooney), Best Supporting Actor (Tom Wilkinson), Best Supporting Actress (Tilda Swinton), and Best Original Score.

There were some surprises in this year’s acting categories. Viggo Mortensen, star of David Cronenberg’s all-but-forgotten drama “Eastern Promises,” joined Tommy Lee Jones (of the little-seen Iraq crime thriller “In the Valley of Elah”) as unexpected nominees for Best Actor (along with Mr. Clooney, Johnny Depp for “Sweeney Todd,” and Daniel Day-Lewis, considered a strong favorite, for “There Will Be Blood”).

Ellen Page, the 20-year-old “breakthrough actor” winner at this year’s Gotham Awards for her turn as an ambivalent, arrogant pregnant teen in “Juno,” kept the momentum going Tuesday with a nomination for Best Actress. The category’s biggest surprise was Laura Linney, who took Keira Knightley’s (“Atonement”) place on the list for her work in “The Savages.” Ms. Page and Ms. Linney were joined by Cate Blanchett (“Elizabeth: The Golden Age”) and frontrunners Julie Christie (“Away From Her”) and Marion Cotillard (“La Vie En Rose”).

Every year, the biggest surprises at the Oscars seem to occur in the supporting categories (remember Arkin over Murphy?), and this year is no different, as two octogenarians snuck into the party on the wings of minor or overlooked roles. Eighty-three-year-old Ruby Dee (“American Gangster”) was the most unexpected nominee for Best Supporting Actress, joining Ms. Blanchett (“I’m Not There”), Saoirse Ronan (“Atonement”), critical darling Amy Ryan (“Gone Baby Gone”), and Ms. Swinton (“Michael Clayton”).

In the Best Supporting Actor category, it was 82-year-old Hal Holbrook who won a surprise nod for his work in “Into the Wild.” Mr. Holbrook will be competing against Casey Affleck (“The Assassination of Jesse James by the Coward Robert Ford”), perennial nominee Philip Seymour Hoffman (“Charlie Wilson’s War”), Mr. Wilkinson (“Michael Clayton”), and favorite Javier Bardem (“No Country for Old Men”).

The foreign film category is regularly the most contentious at the Oscars, but this year really stands out with a most notable omission: Cristian Mungiu’s “4 Months, 3 Weeks and 2 Days,” which won this year’s Cannes Film Festival and found its way onto numerous year-end top 10 lists around the world. The official foreign film nominees are Israel’s “Beaufort” (now showing in Lincoln Center at the Quad Cinema), Austria’s “The Counterfeiters,” Poland’s “Katyn,” Kazakhstan’s “Mongol,” and Russia’s “12.”

In the Best Documentary category, the Academy again reached out to films with political import, as it did last year for “An Inconvenient Truth.” Craig Ferguson’s “No End In Sight,” which made its debut here at Sundance last year, continues to be the leading contender. Mr. Ferguson’s film is joined by Alex Gibney’s “Taxi to the Dark Side,” which made its premiere at the Tribeca Film Festival last year and is currently showing at the Angelika Film Center. Both films directly confront the War on Terror, and will compete for an Oscar against Michael Moore’s “Sicko,” Richard Robbins’s “Operation Homecoming: Writing the Wartime Experience” and Sean Fine and Andrea Nix’s “War/Dance.”

Need fodder for your office Oscar conversation? Here are three thoughts worth ranting about: Johnny Greenwood, lead guitarist for the rock band Radiohead, was snubbed for his astonishing original score for “There Will Be Blood.” The movie “Enchanted” stole three — yes, three! — of the five slots for best original song, edging out the great work of Eddie Vedder, who crafted original songs for “Into the Wild.” And joining “Persepolis” and “Ratatouille,” both expected nominees, in the Best Animated Feature category, was not “The Simpsons,” “Bee Movie” or even “Beowulf,” as some had been guessing. It was, instead, the mediocre penguin surfing comedy “Surf’s Up.”

ssnyder@nysun.com