So why does the third installment of this animated tale often feel so glacial that it's a wonder Ray Romano's Manny the mammoth doesn't freeze in his tracks? Then just when you're nodding off, the tornado that is Scrat and Scratte's squirrelly romance roars through; love unfolding in a free-falling, furry blur. If only director Carlos Saldanha and co-director Michael Thurmeier had undergone some sort of mind-meld that would have brought harmony to the film's competing sensibilities. Instead, 'Dawn of the Dinosaurs' is a sometimes lively, sometimes listless wilderness adventure that will keep the kids cool and mildly entertained for a little while. You'll have to decide for yourself if that's worth the pumped up price it will cost to experience the mood swings in 3-D. John Leguizamo's buck-toothed Sid the sloth is once again one of the highlights of this 'Ice Age,' written by Michael Berg, and Peter Ackerman, Mike Reiss and Yoni Brenner. When we catch up with Sid, he's feeling pressure to start his own family now that Manny and Ellie (Queen Latifah) are getting ready for a baby. A tumble into a deep new cave puts him nose to shell with three large eggs, and with the help of a handy felt tip pen, or whatever form the prehistoric version took, they soon look a lot like Sid. One of the pleasures of the film is watching Sid navigate snow, ice and eggs at breakneck speed suggesting, if nothing else, he has a future in the NHL. Meanwhile, Manny's out baby-proofing the world, not an easy task with all those icicles around, and Diego, the saber-toothed tiger with the low rumble of Denis Leary, is slinking off to sulk about the toll his advancing age is taking. The warm underbelly of this ice age turns out to be where the movie finally starts to heat up. That's right after the eggs hatch and Sid finds himself caring for a trio of tiny Tyrannosauruses who try their very best to be sloth-like, though the whole vegetarian bit is tough. Soon enough their real mom is breathing down Sid's neck, and with a quick crunch, she's got Sid and the kids swinging from her sizable incisors and is headed home. Home is the much warmer Mesozoic era, a surviving archaeological remnant I guess, with the lush tropical landscape a welcome change from all that snow. This land of lizards and flowing lava is more richly conceived, especially the presence of a very engaging one-eyed weasel named Buck (British actor Simon Pegg who did a nice turn earlier this year as Scotty in 'Star Trek'). His long-running battle with Rudy, the dinosaur who relieved him of his eye years ago, breathes life back into the production. As do the romantic interludes between the shticky Scrat (Chris Wedge) and Scratte (Karen Disher). Their body language is really all the communication we need as they struggle between devotion and a very tempting oversized acorn that's always in sight. The 3-D effects are nice enough but, like the rest of the film, represent a larger problem. What 'Ice Age' continues to lack is the level of visual and storytelling inspiration and invention that is increasingly the standard in the animation world. Even the fundamentals sometimes go missing here, particularly in the way the characters interact. It's one thing for the actors not to record at the same time, it's another thing for the film to sound like it. 