Less than seven months after NBC dropped animation in favor of its Saturday “Today” edition, a shift appears to have taken place in the daypart, with the Fox Children’s Network emerging as the biggest beneficiary.Fox, in only its third season, narrowly outdid CBS in the 8 a.m. to noon period during the four Saturdays in the February sweeps, averaging a 6.4 rating, 22 share among children age 2-11 — the main target in the daypart — edging a 6 .3/21 for household ratings leader CBS and ABC’s 5.5/18 by that standard. Buoyed by the hit animated series “The X-Men” and growth among its other shows, the Fox affiliate co-op venture increased its rating by 49% compared to a year ago, picking up much of the audience vacated by NBC, which — with the addition of “Today” and all live-action programming aimed at teenagers — cut loose more than 50% of its age 2-11 audience. CBS and ABC, which have stuck with more conventional children’s lineups, lost a modest 11% and 2%, respectively, in what’s become a tight three-network race week in, week out since “X-Men” started airing regularly in January. ‘X’ wins the spot The appeal of “X-Men” among teens (age 12-17 by Nielsen standards) and older children has also greatly expanded Fox’s reach into that market, where Fox averaged a 23 share compared to an 18 for CBS and ABC’s 16. “X-Men”is even surpassing NBC’s “Saved by the Bell,” an established teen hit, in their head-to-head airing, with a 6.8 rating among teenagers to rival the 6.7 rung up by “Bell.” Observers have long maintained Fox has an advantage in terms of kidvid fare because it can cross-promote its Saturday-morning lineup with its afternoon and morning Monday-through-Friday blocks, when net affiliates are airing talkshows or local news with scant appeal to kids. Fox offers 19 hours a week of children’s programming, more than the 14 it airs in prime time. FCN schedules four hours on Saturday mornings, one more than it did last February. The February results marked FCN’s best performance during a sweeps period and in part illustrate the impact one major success can have in the Saturday-morning arena, where “Teenage Mutant Ninja Turtles,” for example, helped establish long-time leadership for CBS. Fox, however, was quick to point out that its gains have been across the board and not fueled solely by “X-Men.” CBS’ “Ninja Turtles” and “Garfield,” counted as one hour each, were the top-rated shows among kids 2-11 during February, followed by five Fox series (led by “X-Men”), with the Eye web’s “Disney’s Adventures of the Little Mermaid” and ABC’s “Bugs Bunny/Tweety Show” rounding out the top 10.