We're Back! A Dinosaur's Story is a children’s storybook by Hudson Talbott http://en.wikipedia.org/wiki/We%27re_Back!_A_Dinosaur%27s_Story_(book)

One day in the Cretaceous Period as a Tyrannosaurus named Rex is about to devour a smaller dino he captured, a flying saucer piloted by an alien named Vorb arrives. He recruits him and several other dinos he's found for a trial of a special "vitamin" he's developed, which, upon feeding it to the dinos, causes them to become sapient. Vorb takes them aboard his saucer and they travel to the present, dropping them off in New York City, which at that moment is celebrating the Macy's Thanksgiving Day Parade. The dinos pretend to be inflatable balloons to sneak along with the parade, but Rex mistakes one of the real dino balloons to be his friend Allosaurus. The ruse is broken as a result of him accidentally popping "Allosaurus" and the dinos flee as the crowd panics in sight of them. The police come to capture the dinos soon after, but the helpful curator of the American Museum of Natural History, Dr. Bleeb, takes the dinos in, and hides them from the cops by having them pretend to be life-size model dinosaurs. This satisfies the police, who leave to search for the dinosaurs elsewhere, and the curator lets them stay for the night. She reads them a bedtime story about a trilobite who wanted to walk on land, while the dinos watch out the window, unsure about their future.

* Do you know about Rex’s dinosaur friends, names in a storybook were Apatosaurus, Saurolophus, Pteranodon, Triceratops, Stegosaurus and Deinonychus?