There isn't a whole lot of warm-up to the plot of Ice Age: Dawn of the Dinosaurs. We jump right in to find that woolly mammoths Manny and Ellie (voiced by Ray Romano and Queen Latifah) are expecting a baby, giving their pal Sid the sloth (John Leguizamo) a bout of displacement anxiety. To cope, Sid steals dinosaur eggs and starts an "alternative" family, while yet another of their pals, Diego the saber-toothed tiger (Denis Leary) worries that the gang's domestic lifestyle is making him soft. (Yes dads, there's a plotline for you too!)
Things really heat up (har-har) when Sid and his "babies" are abducted and taken to a thawed-out, underground lair of dinosaurs, at which point the gang puts aside their differences to rescue Sid. Along the way, they find yet another zany sidekick, a helium-filled cave, and excuse to fit in the word "cankles."
This Ice Age—the third in the series—is well paced and the addition of 3D visuals is fine. It's not clever like a Pixar joint, but I get the sense that it was supposed to be touching. (I might not be the best judge of such things—during the movie's birth scene, a small boy in the theater cried tenderly, and I found myself unaffected.) Bottom line: You don't have to have see the first two Ice Age movies to follow this one, but if you're older than seven, you might need to see them in order to care.