The fourth movie in this decade-old series could have just settled into a prehistoric groove like its predecessor. But the striking visual effects and quirky humor of this animated CGI offering keep things moving. The plot is far from groundbreaking: Papa mammoth Manny (voiced by Ray Romano) battles a crazy monkey pirate while trying to reunite with his family. But it's Scrat, the saber-toothed squirrel staple of the Ice Age films, who once again delivers the biggest laughs. (The clever use of 3D lets his ever-sniffing snout rub up against audiences.) And Wanda Sykes, as a geriatric sloth, piles on cranky quips from her slobbering gums. A mediocre but mildly entertaining addition to the franchise.